The Orthodontic Treatment ofImpacted Teeth

ADRIA N BECKER BOS, LOS RCS, 000 Re ps

Clinical Associate Professo r, Depar tment of O rthodontics, Hebrew Unive rsity­

Hadassah School of Dental Medici ne, found ed by the Alpha Om ega Fratern ity,

Jerusalem, Israel

MARTIN DUNITZ

CIM..rtin Dumtz Ltd I99S

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CONTENTS

Preface vii

1. Gene ral principles related to the d iagnosis an d treatment of impactedteeth __ 1

2. Rad iograph ic methods related to the diagnosis of impacted teeth 13

3. Surgical exposure of impacted teeth 25

4. Treatmen t strategy 43

5. Maxillary centra l incisors , 53

6. Palatally impacted canines 85

7. Other single teeth 151

8. Impacted teet h in the adu lt 179

9. Cleido crania l dysplasia 199

Index 231

PREFACE

There can be little question th at the treatmentof impacted teeth has caught the imaginationof many in the den tal profession . The cha l­lenge has, over the years, been taken up bythe general p ractitioner and by a n umber ofdental specialis ts, includ ing the paedodonttst,the period on tist , the orthodontis t and, mostof all, the o ral and max illofacial surgeon.Each of these p ro fessionals has much "inpu t"10 offer in the resolution of the immed iateproblem and each is able to show some fineresu lts. However, no sing le ind ivid ual on th isspecialist list can completely and successfullytreat more than a few of these cases, withoutthe assistance of one or more of others ofhis/her colleagues on that list. Thus, the typeof treatment prescribed may depend u ponwhich of these d enta l specialists sees thepatient firs t and the level of his/her experi­ence with the p roblem in h is / her field. Suchtreatmen t may involve su rgica l exposu re andpacking, it may involve or thodontic spaceopen ing, perhaps auto-transp lantation, or asurgical dentoalveolar se t-down procedure,or even just an abnorma lly angulated pros­thetic crown reconstruction .

Experience has com e to show tha t theorthodontic /su rgical moda lity has the poten­tial to achieve the most sati sfa cto ry resu lts, inthe long term. Despite this, many orthodon­tists have ignored or ab rogated their respon-

sibility tow ard s the subject o f im pacted teethto others, accounting for the popularity ofothe r mod alities of treatment. The sub ject hasbecome someth ing o f a Cinderella of den­tis try.

\Vith in the orthodontic /surgica l modality,much room exists fo r d eba te as to whatshould be done first and to wh at lengths eachof the two specialties rep resen ted should goin the zea lous pursuit of its allotted portion ofthe proced ure. The literature o ffers scantinformation and guidan ce to resolve theseissues, leaving th e practitioner to fen d forhim / he rself, wi th a problem th at has ram ifi­cations in several different specialist realms .

This book di scusses the many aspects ofimpacted teeth, includ ing thei r prevalence,ae tiology, d iagnosis, treatment tim ing , treat­ment and progn osis. Since these aspects d ifferbetween incisors and can ines, and betweenthese and the other teeth, a separate chap ter isdevoted to eac h. The ma terial presented isbased on the find ings of clinica l research thathas been carried out in Jerusalem by a smallgrou p of clinicians, over the pas t 15 years orso, at the Heb rew Uni ve rsity - HadassahSchool o f Dental Medicine, fou nd ed by theAlpha Omega Frate rn ity and from the glean­ings of clinical experience in the treatmen t ofmany hund red s of my patients, yo ung andold .

viII

An overall an d reco mmended approach tothe treatment of impacted teeth is presentedan d emphasis is placed on the periodontalprognosis of the results. Among the manyot her aspects of this book, the in tention hasbee n to propose ide as and p rinciples that maybe used to resolve even the most d ifficultim pact ions, emp loying orthod ontic au xil­iaries of many different types and designs.No ne of these is speci fic to any particu la rorthodo ntic appliance system or treatmen t"p hilosophy", notwithstand ing the au tho r'sown pe rsonal p references, which will becomeob vious from man y of th e illustra tions. Theseauxiliaries may be·used w ith equal faci lity invirtually an y appliance system wit h ,vh ichthe reader may be fluent. The only limitationsin the use of these ideas and principles arethose im posed on the reader by h is /her ownimagination and willi ng nes s to adapt.

The o rthodon tic man ufacturers' cataloguesare replete wit h the more commonly and rou­ti nely used attachmen ts, archwircs and auxil­iarics, which Me offered to the p rofessionwi th the aim (If strea m lining the busy prac­tice. These cata log ue items h ave not bee n tai­lored to the demand s of the clinica l issuesthat are raised in this book. Thes e issu es, bytheir very natu re, are exceptional, problem­at ic and often un ique, while occu rri ng along­side and in ad dition to the routine . Amongthe more common limitations self-imposed bymany orthodontists has been the d isturbingtrend to rely so co mpletely upon the use ofp refo rmed an d p re-welded attachments thatthey ha ve forgotten the arts of weld ing andsoldering and no longer carry the necessarymo des t equ ipment. This then res tricts one'spractice to us ing only wh at is availab le andsufficiently commonly used to make it com ­mercially worth while for the manu facturer top roduce. By conse nting to this unhea lthy s itu ­at ion, the orthodontist is agreei ng to workw ith "one h and tied behind his / her back"and treatment results will inevitably suffer.

I acknowledge and am g rateful for th e he lpgiven me by several colleagues; in the prepa­ration of thi s manuscript. An excellen t p rofes­sional relationship has been established andhas withs tood the tes t of time, w ith twosenio r members o f the Department of Ora l

ORTHODONTIC TREATMENT

and Max illofacial Surgery at Had assah, wi thwhom a modus operandi has been devel­oped, in the treatment of our patients.Professor Arye Shteye r. Head of theDepa rtment and, su bse quently, ProfessorJosh ua Lustmann have educated me in thefiner point s of surgical p roced ure an d carewhile, a t the sam e time, ha ve demonstrated arespect an d unders tand ing of the needs of theor thodontist at the time of su rgery. I amgratefu l to them for their collabora tion in thewri ting of Chapter 3.

Dr llana Brin rea d the original manuscriptand made some usefu l suggestions, whichhave been included in the text . I am gratefu lto Dr Alexander Vardimon for his commentsreg arding the use of magnets and to Dr TomWeinberger for the discussions that we havehad regard ing several issues ra ised in thebook. My wife, Sheila, read the earlier manu­scrip ts an d mad e ma ny important recommen­dations an d corrections. More than anyoneelse. sh e encour aged me to keep wri ting d ur­ing the many months when other and morepress ing responsibilities cou ld have beenused as justifiable excuses for putting the pro­ject as ide.

My colleagues, Dr Monica Barzel. DrYccheved be n Basse t, Dr Gabi Engel, DrDoron Hare ry. Dr Tom Weinbe rger, ProfessorYerucham Zilbcrman , and my former gradu­ate stud ents Dr Yossi Abed, Dr DrorEiscnbud. Dr Sylvia Geron, Dr Immanu elGillis, Dr Ra ffi Romano and Dr Nir Sh pack,have provided me with several of the illustra­tions inclu ded here and I am indebted tothe m.

[ am g ratefu l, too, to Ms Alison Cam pbe ll,Commission in g Editor at Martin DunitzPublishers and to Dr Joanna Batragel,Technical Editor, for their con structive andp rofessional critiq ue of the manuscrip t, whichcontribu ted so mu ch to its u ltimate format. Ialso thank Naomi and Dudley Rogg, of theBritish Hernia Centre, for the compu ter an do ffice facili ties that they p laced at my disposalduring my short sabbatical in London, in thelatter stages of the preparation of the work forpublicat ion.

Perm ission to use illust ra tions from myown ar ticles that were pu blished in va rious

PREFACE

learn ed journals was granted by the publish­ers of those journals or by the owners of thecopyright, as follows>

Figu re 5.13 was reprinted from Peret z B,Becker A, Chosak A (1982). The repositioni ngof a traumatically-intruded mature rootedpermanent incisor with a removable appli­ance. [Pcaodont, 6:343-354, with kind permls­sion of the Journal of Pedodontics Inc.

Figu res 5,4 & 5.12 were reprinted fromBecker A, Stern N, Zelcer Z (Copy right 1976)Utilizat ion of a dil acerated incisor toot h as itsow n space maintainer. f. Dmt. 4:263·264, withkind permiss ion from Elsevier Science Ltd .,The Boule vard, Langford Lane, Kid lingtonOX5 1GB, UK.

Figures 9.8-9.14 were reprin ted fromBecker, A., Shteyer. A, Bimstcin, E. andLustmnnn, J. (1997), Cleido cranial dys plasia:

part 2 - a Trea tment Pro tocol for theOrthodontic and Surgical Modality. A m. I.Orthod. Dentojac. Orttiop. 111:173-183, withkind permi ssion of Mosby-Year Book Inc., SI.Louis, MO, USA.

Figure 6.35 was reprinted fromKornh au ser, S., Abed , Y., Ha rary, D. andBecker, A. (1996), The resolu tion of pa lata lly­impacted can ines using pa latal-occlusal forcefrom a buccal auxiliary. Am. /. Orthod.Dentofac. OrthoJ'. 110:528-534, with kind pe r·mission of Mosby-Year Book lnc.. St. Louis,MO, USA.

I am very thankful for their coope rationand for their agreement.

Ad rian Becker[crueolein

1 GENERAL PRINCIPLES RELATED TOTHE DIAGNOSIS AND TREATMENT OFIMPACTED TEETH

CONTENTS • Dental age • Assessing dental age • When is a tooth co nsi dered to beImpacted? • Imp act ed teeth and local space loss • Whose problem? • The timing ofthe surgical intervent ion • Patient motivation and the orthodontic option

In order to und erstand what an impactedtoot h is and whether and when it sho uld betreated , it is necessary to first define our per­ception of normal development of the denti­tion as a whole and the time frame withinwhi ch it operates.

DENTAL AGE

A patient 's growth and develop men t may befaste r o r slower than average, and we mayassess h is or her age in line with this develop­ment (Krogman, 1968). Thus a child may berela tively tall, so tha t his morphological agemilY be consid ered to be advanced. By study­ing rad iographs of the p rogress of oss ificationof the epiphysea l cartilages of the bones in thehands of a young patien t (carpal ind ex) andcomparing this w ith average da ta val ues forchild ren of the same age, we are in a positionto assess the child 's skeletal maturi ty.Similarly, there is a sexual age assessmentrelated to the appearance of primary and sec­ond ary sexual featu res , a mental age assess­ment (lQ tests), an assessment for behaviou rand another to measure a child' s self-conce pt.These ind ices are used to complement the

chronologie age, wh ich is calculated d irectlyfrom th e birth d ate, to give furthe r info rma­tion regarding a particul ar ch ild 's growth anddevelopment.

Dent al age is another of these pa rameters,and is a particularly relevant and importan tassessment, wh ich is used in advisin g p roperorthodontic treatment tim ing. Schou r andMassier (1941), No lla (1960), Moorrce s et al(1962, 1963) and Koyourndjisky-Kaye et al(1977) have d rawn u p tables and d iag ram­matic cha rts of stages of development of theteeth, from initia tion of the calcificationp rocess th rou gh to the co mpl etion o f the roo tap ex of eac h of the teeth, together with theaverage chronolog ie ages at wh ich each stageoccur s.

Eru p tion of each of the va riou s groups oftee th is expected at a particul ar time but thismay be influenced by local factors, wh ichmay cause pn'mature or delayed eruption,with a w ide time-span d iscrepancy. For thisreason, eruption time is an unreliable methodof assessing den tal age.

With few excep tions, ma inly related tofrank pathology, root development proceed sin a fairly constant manner - usually regard ­less of tooth eru ption or the fate of the

2

deciduou s p redecessor. It therefore followsthat the usc of tooth develop ment as the bas isfor dental egc assessment, as determined byexa mination of pe riapical or panoram icXc ravs, is a far more accurate too l.

Thus we may find that a chil d 11-12 yearsold has four erupted first permanent molarsand all the pe rmanent incisors only, wit hdeci duous can ines and mo lars com pletingthe erupted den tition. Were the p racti tionermerel y to run to the eruption chart, he wo uldno ll' that at this age all the permanent caninesand premolars shoul d have erupted and hewould concl ude that the 12 deciduous teethare over-retained and should be extracted!Howeve r. two possibi lities ex ist in this situ­ation, and the radiog raphs must be studiedcarefully to distinguish them from each other.

In the event that the radiographs show theunerupted permanent canines and premolars

THEORTHODONTIC TREATMENT OF IMPACTED TEETH

ha ving completed most of their expected routlength, then the ch ild's dent al and chrono­logic ages coincide (Fig. 1.1). The dec id uoustee th have not shed na turally, because ofinsufficien t resorption of their roo ts. As such ,we have to presume tha t they provide theimped imen t to the no rm al eruption of thepermanent teeth . The ir perm anen t successorsmay then strictly be defined as having de­lap..-d eruption. Under these circumstances, itwould be a logical decision to extract thedecid uous tee th, on the grounds that thei rcon tinued presence defines them as over­retained.

The second possibility is that the radio­graphs reveal relatively little root develop­ment, corresponding more closely perhaps tothe p icture of the 9-year-old chi ld on the toothdevelopment chart (Fig. 1.2). The child's birthcerti ficate may indicate that he is 12 years of

Figu re 1.1

Advanced root development of the canines and premO"lars, de finin g thl'b\.' teeth ,IS exhibiting delayed eruption.Extraction uf the deciduous t"o.'Ih is indicated.

Figure 1.2

An tt -yea r-old patient wi th roo t development definingde nial age as 9 years. Extra ction is con tra ind ica ted .

GENERAL PRINC IPLES RELATEDTOTHE DIAGNOSIS AND TREATMENT OFIMPACTED TEETH 3

age an d this ma y well be su pported by h isbody size and developmen t an d by h is int elli­ge nce. Nevertheless, his de ntition is that of ach ild 3 years younger, defin ing h is d enta l ageat 9 years. Extraction in these circu ms tanceswou ld be the w rong line of treat ment, s ince itis to be expected tha t these tee th will shednormally at the ap pro pr iate delltal age, andearly extraction may lead to the undesiredseq uelae that are characteristic of early extrac­tion . performed for any other reason.

From this d iscussion, we are now in a posi­tion to d efine the terms that we shall useth rou ghout this text. The firs t refers to aretained deciduous tootu. which has a positiveconnotation and which may be d efined as atooth tha t rem ains in place beyon d its normalsh edd ing time . ow ing to absence or retardedd evelopment of the permanent successor. Bycontrast, an d with a negat ive conno tation, ancoer-retained deciduous tooth is one whoseunerupted permanent successor exhibits aroo t developmen t in excess of three-quartersof its expected fina l length (Fig. 1.3).

A permanent toottt unth lida ycd em ptio" is anuneru pted toot h whose roo t is developed inexcess o f this leng th and whose spontaneo useruption ma y, in time. be expected. A too ththa t is not expec ted to eru pt in a reasonabletime in these circumstances is termed animpacted tooth,

Den tal age is not assessed \v ith reference toa single tooth on ly, s ince some vari ation isfound within the differen t groups of teeth.An all-round assessment must be made, andonlv then Gill 01 defin itive de termination beoff~red. However, in d oing this, one shou ldbe wary of includi ng the maxillary lateralincisor s, the m andibular second premola rsand the third molars, whose de velopm en t isnot always in line wit h that of the rem ainingteeth (Garn et al, 1% 3; Sofaer, 1970).

ASSESSING DENTAL AGE

When study ing fu ll-mouth pe riap ical radi o­graphs or a panoram ic film, there are seve ralcriteria tha t may be used in the estim ation oftooth development. The firs t radi ogr aph ic

Figu re 1.3

The mand ibular left second deciduous molar is retained(extraction coneremdjcated), since the roo t dt>,velopmentof its su ccessor is ina deq uate for normal eruption. Theright maxillary deciduou s canine. in oonlrast, is over­ret ained (extra ction advised), SIf\Cl' its long-rooted SUCCl.-~

sor has delayed eru pti on .

signs of the p resence of a too th are seenshortly after initiation of calcification of thecusp tips . Thereafter, o ne ma y atte mpt todelineate the completed crown form ation,various degrees of foo l fo rmation (usuallyex pressed in fractions), through to the fu llyclosed roo t apex. By and large, orthodontic­treatment is perfo rmed 0 11 a relative ly oldersec tion of the ch ild popul ation , and, as such,the stages of root (ormation are usu ally theonlv factors that remain relevant.

The stage of too th developmen t that is easi­est to de fine is tha t rela ting to the closure ofthe roo t apex . For as long as the d enta l papillais di scern ible at the roo t end , the apex is openand still develop ing. Once fully closed, thepapi lla d isap pears and a contin uous laminadura is seen to intimately follow the root out ­line. The accu racy w ith w hich one milY assessfractions of an unm easurable and merely'expected ' final root length is far less reliableand much more subject to ind ivid ual obse rvervariation .

Roo t development of the permanent teet h iscompleted approximately 25 - 3 years afternormal eruption (Nella. 1960). This allows usto conclude tha t, at the age of 9 yea rs, the

4

mandi bular incisors (w hich erupt at age 6) willbe the first teeth to exhib it closed apices an dthat these will usually be closely followed bythe four first permanent molars. At 9.5 years,the mandibular lateral incisors will complete,while at 10 and 11 years respectively, the max­illary central and normally developing lateralinciso rs will be fully formed.

Th is be ing so, when presented with a se t ofradi ographs, we may p roceed to assess denialage by following a s imp le line o f investiga­tion, wh ich uses the dental age o f 9 years asits starting poi nt and then p rog resses for­wards or re-traces its s teps bac kwards,depending upon its find ings.

If the mandibular cen tral incisor roots arecomplete, we may presume the pa tient is atleas t 9 years old (de nt al age), and we maythen advance, chec kin g for closed apices offirs t mo la rs (9-9.5 years), ma ndi bul ar la teralincisors (9.5 years), max illary cen tral incisors(to years), normally developing maxillary lat­eral incisors (11 years), mand ibu lar caninesand first premola rs (12-13 years), maxillaryfirst p remolars (13-14 yea rs), normally devel­oping second p remolars and max illarycanines (14-15 years), an d second molars (15yea rs).

Figu re 1.-1

Root apices are closed in all fir«t molars, all mandibularand three maxilla ry incisors, ("'eluding the monilial)' leftlate ral inciso r.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

By this method, we ma y arr ive at a tenta­tive d iagnosis for den tal age, on the basis ofthe last too th in this sequence that has aclosed apex (Fig. 1.4). It is no v.., important torelate th e actual development of the remain­ing teeth in the sequence to their expecteddevelopment that may be d eri ved from thewall chart o r from tables that have been pre­sented in the literature. Th is may then pro­vid e co rroborative evidence in su pport of thedental age determination.

When the denta l age is less than 9 ye ars,none of the pe rmane nt teeth w ill have com­p leted their roo t de velopment, and the clin i­cian will have no choice but to rely on anes timation of d egree of root developmen t,d egree of cro wn completion and, in the w ryyoung, init ia tion of crown calcif icat ion (Fig.1.5). This is mo st conveniently done by work­ing backwa rds from the ex pected develop­ment at age 9 years and compari ng the dentaldevelop ment status of the patient with this,beginning with the mandibular cen tralinciso rs and the first permanent mo lars. Thus,at d enta l age 6 years, on e wou ld find one-halfto two-th ird s root leng th of these teeth. andthis could be corroborated by stu dying thed evelopment of the other tee th . At the same

Figure 1.5

Xo closed apices. Dental age assessment 7.5 }'N T'5.

GENERAL PRINCIPLES RELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH 5

time, one sho u ld expec t une ru pted ma xillarycentral incisors wit h one-half root leng th,mandi bular canines with one-third roo tlength, first p remolars with one-qu a rter roo tlength, and so on.

As pointed ou t earlier, va ria tion occurs,and this may lead to certain apparent contra­d ictions. In such cases, elim ina ting the ma xil­lerv lateral incisors, the mand ib ula r secondpremolars and the th ird molars w ill usuallysimplify the p roced ure an d contribute to itsaccuracy, s ince these teeth are more ind ivi­d ually va riable co mpa red with the res t ofthe dentition. Ad d ition ally, un usually smallteeth, cun iform premolars and mandibularincisors, and peg-shaped lateral incisors aremos t often to be seen developing very muchlater (sometimes as much as 3 or 4, yearslater), and should not bt> inclu ded in the over­all estimation. One may then present a deter­mination for the den tition as a whole, w iththe added not ation tha t an ind ivid ual too thmay have a mu ch lower den tal age.

We ma y occasionally examine a I-t-year-oldpa tient who has a co mplete permanen t den ti­tion. including the secon d molars, with theexception that a mand ibu lar second d ecidu­ous molar is present. The radiographs (Fig.1.6) show the apices of the first molars, cen­tral and latera l incisors, ma nd ib ular caninesand premolars to be closed , wh ile the maxil­lary canines and the second mo lars are almostclosed . Howeve r, the u neru pt ed ma ndibular

Figure 1.6

A late-developing left mandibular second premolar.(Courtesy of Dr M Baezel.)

seco nd premolar has an o~1l'n root apex andd eve lopment equ ivalent to abou t half itseventual length . On the basis of the informa­tion gathered , we may assess the dental ageof the den tition as a whole to be 14 yea rs. Atthe same time, we should have to note tha tthe d en tal age of the unerupted second p re­molar wa s approximately 10 years. Ha vingmad e th is determination, we may now con­fid ent ly say that the second premolar, in­d ivid ua lly, d oes no t exhibit delayed eru ptionand the deciduou s secon d molar is not over­retained, in the terminology used here.Accord ingly, it would not be appropriateto extract the deciduous too th at this time, butto wait at least a furthe r 2 years, at whichtime the tooth may be expected to shed nor­mally.

To summarize th is d iscussion, it is essentialto d iffere nt iate be tween fou r d ifferent con di­tions that may exist when we encounter ade ntiti on that incl udes certain deciduou stee th, inco ns istent with the patient' s chrono­logic age. Becau se the ens uing classification ofthese con di tion s is treatment o riented, thelabelli ng of a patient with in one of thesegrou pings ind icates the treatment that isreq ui red.

A late-de7.'t'/oJ'ifl~ dentition, The dental ageof the pa tien t lags behind the chronologieage, as witnessed radi ogra phica lly by lessroot forma tion than is to be expec ted at agiven age, in the entire d entition.Typ ically, thi s will be evide nt clinicallyby the continued and sy mmetrical p res­ence of all the decid uous m olar s andcani nes on each side of each jaw.Extraction o f deciduous teeth is con­traindi cated at this time.

2 Goer-retained deciduous Ict'/II. The dentalage of the pa tien t ma y be posit ively co rre­lated wit h th e ch ronolog ie age, bu t theradi ogr aph shows an ind ividu al perma­nent tooth or tee th with we ll-d evelopedroots, w hich rema in une rupted . Th istends to be local ized in a single area andmay be d ue to an ec topic siti ng of the per­manen t tooth bud, which has s timula tedthe resorp tion o f only a po rtion o f theroo t o f its d ecid uous p redecesso r, bu t

6

shedd ing has not occurred becau se of thepersistence of the remaining part of theroot or of a second and unresorbed root.Neverthe less, the condition ma y occa­sionally be fou nd symmetrically in asingle den ta l ar ch or in both arches.Extraction of the over-reta ined teeth isindica ted.

3 A normal del/ falase , with si/Ig le or multiplelate-dt'!.t'lopil/g p CrIIJr1I1t' lI f leeth. This condi­tion is commonly found in relation to themaxillary lateral incisor and the man­dibular second p remola r teeth. and ex­traction of the deciduou s p red ecessor isto be avoided.

-t A combination of the abooe. Sometimes onemay see featu res of each of the abovethree alte rnat ives in a single de ntition.

The im po rtance of interpreti ng the d ifferen­tial d iagnosis for a given patient cannot beoveremphasized, since it ha s far-reach ingeffects on all th e as pects of diagn osis, treat ­ment planning and treatmen t tim ing for caseswi th impacted teeth .

WHEN IS A TOOTH CONSIDERED TOBE IMPACTED?

From the work of Oren (1962), we learn thatunder no rmal circumstances a too th eruptswith a developing roo t and wit h approxi­ma tely three-qua rters of its final roo t length .The man dibula r central incisors and firstmolars ha w marg inally less root develop­ment and the mand ibula r can ines an d secondmolars margina lly mo re when they eru p t. Wemay therefore take this as a d iagnostic bas e­line from which to assess the er up tion of teethin general. Th us, shou ld an erupted toothhave less root development (Fig. 1.7), itwould be appro pri a te to label it as prematurelyerupted. This will usually be the consequenceof early loss of a deciduous too th, particularlyone whose ex traction w as dictated by deepcaries, with resul tan t pe riapical pa thology.

At the opposite end of the scale. we find theunerupted tooth that exhibits a more com­pletely de ve loped roo t. The no rmal eruptionprocess of this too th must be p resu med to

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

ha ve been imped ed by on e of several actio­logic possibilities . These includ e such factorsas a failure of resorption of the roo ts of ad ecid uous too th, an ab normal eruptive pa th,a supern u mera ry too th, d ental crowd ing or ad isturbance in the eru ption mechan ism o f thetoo th. However, obstruc tion may also res u ltfro m a thickened post -ext raction or pos t­tr auma repair o f the mucosa (Figs 1.8<1, b).

No t in frequently, and particular ly in themandibular premolar region, there may be ah istory of very ea rly extraction of one or bo thdecid uous molars. Delayed or no n-e ru ptionof the premolars will occur, owing to a thick­ened mucosa overlying the teeth . It may bepossible to pa lpate these teeth, their d istinctou tline being clearly seen bu lging the gum fora pe riod of year or more, although eru ptionmay no t occur.

IMPACTED TEETH AND LOCAL SPACELOSS

A time lapse ex ists between th e pe rformanceof a su rgical procedure to remove the cause ofan impaction and the full eru ption of th eim pacted tooth into its p lace in the dentalarch. The extent of th is time span is de pe n-

Figure 1.7

The left mandibular premolars are prematu re ly eru pted.....ith insufficien t root d...vclopment.

GENERAL PRINCIPLES RELATED TO THEDIAGNOSIS AND TREATMENT OF IMPACTED TEETH 7

(.)

(b)

Figun" 1.8

(a) Th~· right mandibular second premolar was extractedat age 8.5 y l',lfS. (b) Seen ill age 11. the rool of theunerupted firs l premolar is alm ost com pleted .

dant on severa l factors, such as the initial d is­tance between the too th and the occlusa lplane, the stage of the de velop ment of theparticular tooth, the age of the pati ent, andthemanne r in which hard and soft tissue may belaid down in the healing wound . During thislime period, therefore, local changes in theerupted den tition may occur as a resu lt of thebreak in the integrity of the den tal archcaused by the surgical procedure, such asspace loss and tipping of the adja cent erupted

teeth. This inte rvention is no less susceptibleto the drifting of neighbou ring teeth than isany other factor that may produce inte rp roxi­mal loss of dental tissue.

With an od ontom e or supernumerary toothin the pat h of an uneru pted permanen t tooth,vertical (and sometimes mesial or distal orbuccal or lingual) d isplacement of the per­manent tooth is likely to be considerable.It wo uld be convenient if the removal of thespace-occupying body cou ld be performed,leaving the deciduous teeth intact, sincethe deciduous tooth would mainta in archintegrity duri ng the extended period of timeneeded for the permanent tooth to eru pt nor­maUy. Unfortunate ly. often, in orde r to gainaccess to perform the desi red surgery. one ormore deciduous teeth need to be extracted.This being so. and having regard for the longdistance tha t the displaced permanent toothhas to tra vel. space maintenance should berega rded as esse ntial in most cases. It sho uldbe the first or thodontic procedure to be con­sidered in these cases and it sho uld beretained until full eruption has occurred.

Impacted teeth are often associated with alack of space in the immed iate area. This isfrequently due to the drifting of ad jacen tteeth, alth ough crowd ing of the dentition ingenera l may be the prime cause. In suchcases, the spontaneo us eruption of animpacted tooth is unlikely to occur unlessadequate or, preferab ly, excessive space isprovid ed. It wo uld be convenient if the exci­sion of the associa ted pathologic entity couldbe comfortab ly delayed un til this time, tobring about the desired eruption and to per­mit this correc tive treatment to be attemptedwhen the root developmen t of the unerup tedtooth is ade quate. However, the surgeon willinsist on removi ng most forms of pathologyas soon as a tentative diagnosis is reached, inorder to obta in exami nable biopsy ma terialfor the establishment of a definitive diagnosis.Odontomes and su pernumera ry teeth aTCgenera lly conside red to be exceptions to thisru le, and the timing of their removal may bemo re leisu rely cons ide red.

8

WHOSE PROBLEM?

Patients do not go to their den tist com plain­ing o f an impacted too th. They are frequentlyunaware tha t th is abnormality exists, sincethere is no pain, d iscomfort or swelling.Neither is it obvious to the layman that thereis a miss ing tooth, since the decid uous pred e­cessor is usually reta ined. The vas t majorityof impacted teeth come to light by chance, inrou tine dent al exa mina tion, and are not theresult of a patient' s d irect complaint. As ageneral rule, it is the paedodontis t or generalden tal p racti tioner who, du ring a routineden tal examination, discovers and records theexistence of an over-retained deciduous too th .A periap ical rad iograp h will then confirm thed iagnosis .

There are two principal excep tions w herean abno rmal appearance may be the reasonwhy the patient seeks professional advice.The first usually' brings the patien t to theoffice at the age of 8-10 years, when a singlemaxilla ry central incisor will have eru pted ayea r or so earlier and the pa ren t points ou tthat the erup ting lateral inciso r of the oppo-­site side has not left enough space for theexpected eruption of the second cen tralincisor (Fig. 1.9). Often, the deci duous cen tralincisor is retained . In this situation, the paren thas recognized abnormality, bu t will notgenerally have the technical understand ing tosuggest the possibility of impaction o f theunerupted central incisor .

Figure 1.9

Unerup ted right maxil1<l ry central incisor with spaa' loss.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

The seco nd exception occu rs w ith a 14--15­yea r-old patient who requests the restorati onof an unsightly cariou s lesion on a retainedmaxillary decid uous canine. Gene rally speak­ing. the pati en t will be unaware tha t this is nota permanent tooth, and it will require suitableprofessional advice to point ou t that restora­tion is probably no t the appropriate line oftreatm en t, rather extraction and the reso lut ionof the impaction of the permanent canine.

A very small percentage of cases maybe seen initially by their genera l denta l prac­titioner because of symptoms related torelatively rare complications of im pactedteeth . Among these symptom s ar c mob ilityor migration of ad jacent teeth (d ue toroo t resorp tion), pa in less bony expansion(dentigerous or radicular cys t), or perhapspain and I or discharge (in fected cyst, w ithcommun ication to the oral cavity) (Shafer etal. 1983).

In itially, the p ractition er should ascertainwhet her there is a good chance that resolu tionwill be spon taneous, on ce the aetiologic factorhas bee n removed, or whether active appli ­ance therapy w ill be needed . To be in a posi­tion to do this, the exact position , long-axisangulation and rot ational status of the toothhave to be accurately visualized and anassessment of space in the arch must bemade. Followi ng this initial assessment, thepedodontist or general de ntal p ract itionernow has to decide who should treat the p rob­lem.

Many general p racti tioners will p refer notto accept responsibility for the case, and w i11refer the patient to an oral and maxillofacialsurgeon, on the basis that surgery will beneeded. Many surgeons will agr ee that theproblem is essen tially surgical in na ture, andwill proceed to remove retained deciduousteeth, clear away othe r possible aettolo gtc fac­tor s, such as supernumerary teeth, odon­tomes, cys ts an d tumours, and will alsoexpose the impacted permanen t too th . If theim pacted tooth is buccally located, the su rgi­cal flap may be apica lly repositioned, to pre­vent primary closu re and to ma intainsubsequent visua l contact w ith the impactedtoo th after healing has occurred . This willhave the effect of encouraging eruption in

GENERAL PRINCIPLES RELATED TO THE DIAGNOSISAND TREATMENTOF IMPACTED TEETH 9

ma ny cases. Un til hea ling (by 'second aryinte ntion' ) has occu rred , the wound will usu­ally be packed with iod oform gauze impreg­na ted with Whitehead 's va rn ish, over aperiod of a few weeks. Ca reful placement andwed ging o f th e pack between an impactedtooth and its neighbour is used by surgeonsto he lp free the tooth to erupt na tu rally, whenthe pack is later removed. Of ten, in more di f­ficult impactions, wider su rgical exposure isundertaken, includ ing fai rly radical boneresection, both around the crown and downto the CEl, w ith complete rem oval of the den­tal follicle.

Following a period of many months and(for some more aw kw ard ly positioned teeth )sometimes extend ing int o years, the su rgeonwill usually then follow up the spontaneouseruption of the impacted tooth until it reachesthe occlusal leve l. If, at that tim e, alignment ispoor or the too th still has not eru pted, thepatient w ill be referred to the orthod ontis t.

The paed od on tis t or ge ne ral dental practi­tioner may alternative ly and preferably referthe pat ien t di rectly to an orthod ontis t. Cer­tainly, the orthod on tist cannot d irectly influ­ence the position of the im pacted tooth untilappropriate access has been p rovided su rgi­cally and an attachment has bee n placed onthe tooth. Nevertheless, with proper planningand management , includ ing the refer ral forsurgical exposu re at the appropriate stage inthe treatme nt, a much higher level of qualitycare may be p rovided and in a very muchshorter time frame . This will be d iscussed inthe ensuing chapters of this boo k.

THE TIMING OF THE SURG ICALINTERVENTION

From the above d iscussion, we see thatthe timing and nature of the su rgica l p roce­dure are determined by the d eg ree of devel­opment of the teeth concerned at the timeof initial d iag nos is. At an early stage, aradiographic su rvey of a very yo ung chil dmay reveal pa thology, such as a su pern u m­erary too th, an odontome , a cys t orbenign tu mour , that ap pears like ly to preven t

Figu re 1.10

A midline supernum era ry tooth (rnesiodens] discoveredin routine periapica l radiographic view of the maxillaryincisor area.

the no rmal and spon taneous eruption of aneighbouri ng tooth .

At this s tage, from every point of view, itwou ld be inap prop riate to expose the crownof an im matu re too th. In the first place, onewould no t wa n t to encourage the toot h toerupt before an adequa te (half to two-thirds)root len gth had been p roduced . Secondly , atthis early stage of its development. the too thcannot be consid ered as impacted , and, giventime and freedom to manoeuvre, will prob­ab ly eru pt by itself. Early exposure risks thepossibili ty o f d amage to the crown and to thesubsequen t root development of the tooth .

Nevertheless, with the d isco very of thepathological condition (Fig. 1.10), the pot en­tial for impaction exists, and leaving the con­d ition untreated will worsen the prognos is.Accord ingly, rem oval of the pa tho logicalen tity, withou t d istur bing the ad jacen t pe r­manent teeth o r the ir follicular cry p ts, shouldbe the aim of an y treatment at that time. Itma y then reasonably be expected that normaldevelopment and erup tion w ill occu r in thefullness of time. Wh ils t this is an obviou slydesi rable co urse of action, access to the tar­geted area may be th warted by the presenceand closeness of adja cent developing st ruc­tu res, and delay may still be advised .

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH10 ________ __"-'----'-'-C----"----=---=--'--------=--=::..--=..'-

Figure 1.11

Thl' p,lO<J ramic rad iugraph shows erup ted maxillar y lat ­eral incisors an d over -retained d.'c id" ous ..ental incisors.TI1<.' unerupted cen tral incisors may be seen superiorly tothe two unerupted supernumerary teeth . (Courtesy ofDr I Gi 11i~. )

The second scenario occurs when the con­d ition is only d iscovered much later . In th iscase (Fig. 1.11). the permanent tee th may jus­tifiably be defined as impacted, and the aimsof surgical treatme nt become twofo ld: first, toelimina te the pathology, and then to createop timal cond itions for the erup tion of the per­manent tooth, which is alread y late. Th is willusua lly involve exposure of the crown of thetoo th. For many teeth , given adequa te spacein the dental arch and little or no disp lace­ment of the impacted toot h, spon taneouseruption may be expected (Dibiase, 1971;Mitchell and Bennett. 1992). As w e sha ll seein subsequent chapters, there arc several situ­ations and tooth types where this may notoccur, o r it may no t occur in a reasonabletime fra me, often because of severe di sp lace-­ment o f the affected tooth . Fo r these cases,the natural erup tive potential of the tooth issupplemented and, if necessary, diver tedmechanically, with the use of an orthodonticapp liance.

PATIENT MOTIVATION AND THEORTHODONTIC OPTION

Angle's Class II ma locclus ion is present inbetween one-fifth and one-qua rter of the childpo pulation in most countries of the westernworld (Massier and Fran kel, 1951; Brin et al,

1986). However, even a cursory analysis ofthe pa tient load of any give n or thodonticp ractice will reveal a round three-quar ters ofthe pa tients being treated for this ma locclu­sion. The reason for this has to do wi th thefact that a pa tien t' s appearance is adverselyaffected to a grea ter exten t by this conditionthan by most oth ers. In other word s, appear­ance plays an inordina tely large part in theinitiative and motivation on the part of theparen t of a young pa tien t to see k treatmen t.

A signi ficant sectio n of the remaining q uar­ter of the patients in this hypothetical ortho­dontic p ractice are being treated for variousless unsightly con ditions (crowding, singleectopic teeth, open bites or class 3 relation­ships). Thi s leaves on ly a few pa tien ts in thispractice sample who have been refe rred fo rstrictly hea lth reasons, which may not beobvious to the pa tient.

Appearance is not a problem for th is smallgro up of patien ts, wh o will have ag reed toorthodon tic treatment only after motivat ionhas been evoked by the carefu l and persua­sive explanations of a dentist, o rthodont ist ,pe riodontis t, p rosthodontist or o ral surgeon,regarding the ills that are othe rwise likely tobefall them and their dentitions.

Most impactions arc symptomless, and,as ide from maxillary central incisors, do notusua lly present an ob vious abnorma l appear­ance. Accord ingly, mo tiva tion for treatmentin these cases is m in ima l, and much time has

GENERAL PRINCIPLESRELATED TO THE DIAGNOSIS AND TREATMENT OF IMPACTED TEETH 11

to be spent with the patien t before he or sheagrees to trea tme n t. The s tory d oes no t endthere, s ince these pa tien ts ma y often requireperiodic ' pep talks' to ma intain their level ofcooperation and the ir res ol ve to co mplete thetrea tment. Many of them w ill no t main tainthe required standa rd of oral hygiene, and,while it is d ifficu lt to jus tify continuing treat­ment in these circumstances i ~ is just as d iffi­cul t to rem ove applian ..o.:'~ rrom a patient inthe mid d le of treatme n t, when impacted teethhave bee n pa rtially erupted and large spacesare presen t in the dental arch. For these rea ­sons. wh ile ambitiou s and innovative treat­ment p lan s may be suggested , it is essential totake the moti vation factor into account beforeadvis ing lengthy and com plicated treatmen t,since the risk of non-completion may be high.

REFERENCES

Brin I, Becker A, Shalhav M (1986) Position ofthe maxillary permanent can ine in relation toanomalous or missing lateral incisors: a popu­lation study. Ellr / Orthod8: 12-1 6.

Di Hi,lSC DD (1971) The effects of variations intooth morphology and position on eru ption .Dellt Pmct Dent Rec 22: 95-108.

Gam SM, Lewis AB, Vicinus JH (1963) Thirdmolar polym or phism and its s ignificance todenta l genetics. JDelli Rt'S42: 1344-63.

Gran A·M (1962) Pred iction of tooth emer­gence. JDCllt Res 41: 573-85.

Koyou md jisky-Kaye E, Bares M, Gro ve r NB(1977) Stages in the emergence of the dent i­tion: an im proved classi fication and its appli­cat ion to Israeli children. Growth 41: 285--96.

Krogm an WM (1968) Bio log ical timing andthe den to factal com plex . J Dent Child 35:175-85.

Massier M, Frankel JM (1951) Preva lence ofm alocclus ion in child ren aged 14-18 yes. Am JOrtnod37: 751-60

Mitchell L, Bennett TG (1992) Su pern u me raryteeth caus ing delay ed eru ption - a retrospec­tive study. Br JOrt}IOO 19: 41-6.

Moorrees CFA, Fanning EA, Oren A-M,Leb ret L (1962) The timing of orthodontictrea tment in relation to too th form ation . TransEflr Ortnoa Soc 38: 1- 14.

Moorrees CFA, Fann ing EA, Hunt EE Jr(1963) Age va ria tion of for ma tion stages forte n perma nent teeth. J Dellt Res 42: 1490-502.

Nella CM (1960 ) The development of perma­nent teeth. / Dent Child 27: 254- 66 .

Schou r I, Messle r M (1941) The developmentof the hu man d en tition . J Alii Dent Assoc 28:1153-60.

Shafer WG, Hinc MK. Levy BM (1983) ATexbook of Oral Pathology, 4th ed n. WBSau nders, Philad elph ia.

Sofaer JA (1970) Dental morp holog ic varia­tion and the Hardy Weinberg law . J Dellt Res49(Sup pl), 1505.

2 RADIOGRAPHIC METHODS RELATEDTO THE DIAGNOSIS OF IMPACTEDTEETH

CONTENTS • Qual itative rad iography• CT scann ing

It is not the purpose of this chap ter to presenta complete manu al on dental radio graphy,but rather 10 concisely highlight those tech­nique s an d meth od s tha t are usefu l in theclinical setting, as it pe rtains to impactedteeth. The methods offered have two mainaims (Sewa rd , 1968; Hun ter, 1981). The firs trelates to the fu rn ishing of qu ali tat ive infor­mation regard ing no rmal and abnormalcondi tion s that may be associated w ithunerupted teeth . Thu s the d ifferent ways ofradiologically displ ay ing and recognizingpathological entities, such as supernumeraryteeth, enlarged eruption follicles, odon tomes,root resorption and other patholog ical en ti­ties, arc dis cus sed and compared . The secondaim is to describe the var ious radiologicaltechniqu es that the clin ician may find helpfulin accurately pinpointing the position of aclinically invisible, unerupted tooth . The rela­tive merits of these techniques ar e di scussed,and ind ications for their use arc suggested inrelation to the di fferent groups o f teethinvolved .

• Th ree-d imensional diagnosis of tooth po sit ion

QUALITATIVE RADIOG RAPHY

Periapica l radiographs

The first, simplest and most inform at ive X-rayfilm is the pe riapical view. This view is orien­ted to pass through the minimum of su r­rounding tissue. in order to give accu racy andquality of resolut ion . It is generally aimed tobe perpendicular to an imaginary planebisecting the angle between the long axis ofan erupted tooth and the film plane, to pro­duce the minimum of distortion. The penapt­cal film is designed to view the tooth itselffrom the angle of best advantage, without anyrelation to its position in space.

From this film, it w ill be immediately obvi­ous if there is an impacted tooth and if itsstage of development is sim ilar to that of itserupted an timere, w ith at least two-thirds ofits root length . The presence and size of a fol­licle will be obvious, and it will be possible toasce rtain crown or roo t resorp tion, root pat­tern and integrity . The presence and descrip­tion of hard tissue obstruction w ill be evident,allowing the observer to d istinguish connate,in risiform and barrel-shaped supernumer­aries, and odontomes of the complex or

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH14 ...::.::.:::...::.:==:::...:.==::.::-=..:==::::..:.:::.::.:

com pound com posite types. Simila rly, it willshow soft tissue lesions, such as cysts. Thegrea t clarity offered by the view is superior tothat of othe r views, and it should always beused as the init ial film of a suspectedimpacted tooth in a radiographic exam ina­tion. As with any radiogra phic film, however,the periapical view is only twa-di mensional,and gives no information in the bucca- lingualplane; overlap ping structures cannot bedifferentiated as to which is lingual an dwhich buccal.

For this film to give the most advantageousview of the tee th in the maxillary arch and inthe mandib ula r an terior segment, the centralray of the periapical view is oblique, and willvary between 20° an d 55° to the occlusa lplane (Mason, 1982), depending upon theregion to be x-rayed. Given this obliquedirection, any attempt to estimate the heightof the tooth or its bucca-lin gual orientation.without ad di tional info rmation, must fail.

When pe rforming pe riapical radi ographyon the poste rior teeth in the mandibular arch,however, the most advan tageou s directionhas the centra l ray very close to the horizon­tal, and, as such, also offers a true lateral viewof these teeth. Thu s not on ly will the observersee the most precise de tail of the too th and itssurrou nding tissues, bu t it will also be possi­ble to accurate ly assess its heigh t in the jaw.

Occlusal radiographs

Mandibular arch

In the mandi bu lar arch, this view is properlyexecuted by tipp ing the patient's head back­wards an d pointin g the X-ray tube at right­angles to a film, held between the teeth, in theocclusal plane (Fig. 2.1). In the lowercanine / premolar region, the occlusal view isa 'true' occlusal view an d sho uld de pict allthe posterior standing teeth in cross-section.As su ch, it shou ld also provide bucco-lingualpositional information on the tooth and an yassociated structu res in a plan e at righ t anglesto tha t seen on the periapical film. Because ofthe thickness of bone traversed, de tail ismu ch poorer, unless there is expansion due to

Figure 2.1

Taking a true occlusal view of the lowe r jaw: for thecanine / premolar region and for the incisor region.

a large cyst or bucca-lin gually displacedtooth.

In orde r to produ ce a true occlusal view inthe anterior reg ion of the mandibu lar arch(Fig. 2.1), the head will need to be tip ped backfurther and the tube pointed at the symphysismenti, at an angle of 110° to the horizon tal, inline with the long axes of the incisor teeth. Toachieve the same for the molar teeth, the 90°angle to the horizontal will need to be aug­men ted by a 15° medial tilt of the tube, tocompensate for the characteristic sligh t lin­gua l tipping of these teeth (Mason, 1982).

Maxillary arch

Maxillary anterior occlusal. In the maxillaryarch, the nose and forehead interfere with thepositioning of the x-ray tube, close to the areato be viewed . The best that can be achievedby positioning the tube close to the face is ananterior maxillary occlusal view of the teet h,wh ich is perhaps bet ter descr ibed as a high orsteeply-angled pe riapical view (Fig. 2.2). Theview will 'shorten' the actual length of theroots, bu t it will be a far cry from the cross­sectional view that is so easy to achieve in themandibular arch. Since the central ray passes

RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH 15

\ \ !JiJ !J" Occtosat~ " plane

Figure 2.2

A di ag ram showi ng incisor inclination, film pos ition andcen tral X-ray beam, d ifferentiating the periapical " lew,the anlt'rior (ob lique) occlusal view and the true verte xocclusal views.

Figure 2.3

A trw.' vertex occlusal film usi ng On g' s pmjl'rtion, show­inll) two palatal canines. The right canine is ChlSl' to thearch and almost vertical. The cro wn of the Il'fl caninereaches the midline sut ure, while the Toot apex is close tothe line of the a rch.

ante rior teeth will be seen in their cross­sectional view as small circles with a tiny con­centric circle in the cen tre, denoting the pulpchamber. No information is available regard­ing the relative height of the object in thealveolus, and it certainly cannot be used forfine detail. A single tooth that is palatal to theline of the arch will ap pear wit hin th is arc ofsma ll circles. If the too th is at an ang le, notparallel to its neighbours, it will show up initselliptical, oblique cross-section, repres enting atilted long nxis. If the tooth is horizon talacross the palate, its full length will be obvi­ous on this view, togethe r with the exactmesio-d istal and bucco-lingual or ientation ofboth the root an d the crown, in the hor izontalplane (Fig. 2.3).

The di fferen ce between the two types ofocclusal film may not seem to be very great,but it sho uld be app reciated that, from thevan tage po int of an anter ior occlusal film, theanterior tee th will be foreshor tened but willstill have appreciable length. In this situation,a high and mesially placed labial canine couldgive precisely the same picture as a low andmesially placed palatal canine. This could nothappen in a vert ex occlusal projection.

Periapical

Anter ior occluul(60" to ccchrsa l plane)

Vertex occluuJ (110" \to occluu l plane)

through less thickness of bone, detail is usu­ally good, alt hough no t as clear as with theper iapica l view .

True (i xrtex) occlusal. A true occlusal viewof the anterior maxilla is a view in which thecentra l ray of the X-ray beam runs pa rallel tothe long axis of the centra l incisors (Fig. 2.2).This is only possible when the cone is placedover the vertex of the skull, to produ ce thevertex occlusa l film. Since the beam has totravel a great d istance through the craniumand its contents, the base of the skull and themaxilla, there is a conside rable loss in clarity.Recently, an excellen t method of prod ucingthis view extra-orally has been described(Dog. 1994). In order to avoid the need for avery long exposure, a fast film should be usedin a cassette with intensifying screens. Forthese reasons, the method is no t popular.

Nevertheless, in this view (Fig. 2.3), all the

16 THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(a)

Ie)

Ibl

[dl

[e)

Fig u re 2.-1

(a) The periapical view shows an Impacted Ie-ft maxilla ry central incisor, due to an inverted unerupted sup,'munwr,uytooth. The decid uous too th is over-re tain ed. Accu ra te di ag nosis of the hd~ht of the im p.1(il'd tooth in thc, alveolus is notpossible from this view. (b) The anterior maxilla , see n on oil lateral Cl.'phaluffielric radiogra ph. shows the high impil(tNcentra l incisor, facing the labial sulcus; Ic) and (d) representtf c SolID,' views a" (a) and (h) afte r removal of the SUf"?T­

numeral)' tooth an d bracket bonding to the exposed incisor. (Courl.~y of Dr D Hara ry.I (e) A pa rallel in tra-ora l photo­gra phic view. This film has been lM"rally inverted to simplify comparison.

-RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH 17

Extra-ora! radiographs

The panoramic view, while not showing thesame degree of detail as a periapical film, hasthe advantage of simply and quickly offeringa good scan of teeth and jaws, from TM jointto TM joint. It is p robably true to say thator thodon tists are tod ay in general agreementthat this film gives the most qualita tive in fe r­mation. to act as a starting point from wh ichto proceed to other forms of radiography, inline wit h the deman d s o f the pa rt icular s itu­ation in any given case.

True and ob lique lateral ex tra-ora l views(Figs 2.4a-e) and the va riousl y angu latedoblique occlusal films all pro vid e info rmationthat may be used to complement the periapi­cal film, particularly when too th displace­ment is severe. However, the use of anyoblique film for the accurate localization of aburied too th may frequently be misleading,be it a single pe riap ical, an occlusal or a lat ­eral jaw film . This being so, two incipientdangers exist . First, as we shall see in laterchapters, a surgical procedure may be mis­directed and a flap opened on the wro ng sideof the alveolar p rocess. Second ly, misin terp re­tat ion of the too th' s position may lead theoperator to assume a very favou rable progno­sis for biomec hanical resolution when, in fact,the tooth may be in a co mpletely intractab leposi tion. Thus the choice of treatment will beinap propri ate.

THREE-DIMENSIONAL DIAGNOSIS OFTOOTH POSITION

As dentists, we arc very used to seeing peri­ap ical films of ind ivid ua l teet h, and, p rov idedthat the teeth concerned are in the line of thearch, these films have many advantages.However, in th is view, the x -ray tube is no tdirected in the true horizontal, true ver tical ortrue lateral planes. Aside from radiography ofthe mand ibu lar posterior tee th, the tube isalways tipped at an angle to one or more ofthese planes . Th is is un important for aneru pted too th, s ince the th ird di mension issupplied by the di rec t vision within the

mou th. Thu s, while it gives a good two­d imensiona l represen ta tion of the tooth, thisview has lim ited value when vis ua lization ofan unerup ted too th is req uired, in the threeplan es of space .

PARALLAX METHOD

By following the p rincip les in volved in binoc­ular vis ion, two pe riapical views of the sameobject and taken from slightly d ifferent anglescan provid e de pth to the flat, two-dimensionalpictu re depicted by each of the films individ­ually (Fig. 2.5). Thi s is of considerable helpwith distinguishing the bu ccal or lingual d is­placement of the can ine, which is low d ownand fairly close to the line of the arch. Thep rocedure is performed in the following man­ner (Fig. 2.6).

1 A periapically sized film is placed in themouth, with the patient' s finger holding itagainst the pa latal as pect of the areawhere the too th wou ld no rmally be situ­ated. The x-ray tu be is d irected at right­ang les to a tangent to the line of the archat this poi nt, as for any peria pical view

Figure 2.S

The left periapical view. oriented for the central incisor s,shows the crow n of the camne superimposed on the d is­tal half of the central incisor mot. Th~' rmddlc film,rotated 30" to the left, shows the canine overlapping onlythe lat eral tnctsor roo t. By ml aling the cen tral beam ,1 fur ­ther 30", superimposition of Itll' canine over the lateralincisor root has been eliminated. The canine is pillol tallydisplaced.

THEORTHODONTIC TREATMENT OF IMPACTED TEETH18 ------- - ------'-'-----'---------'------

Fig ure 2.6

A d iagra mmatic representanon of the parallax method . Ifthe \ll.~·n·d~ '-'y t' p''t.'n; along the axis of the X-ray beam ineach Col"". the image on lilt>film will be easy to I\'CUJ15truct.

and at the appropriate angle to the hori­zonta l plane.

2 A second film is pla ced in the mouth inthe identical posit ion, bu t on th is occasionthe X-ray tube is sh ifted (rotated) mesi­ally or d ista lly round the arch, but held atthe same angle to the horizontal p laneplane and di rected at the mesially or dis ­tally adjacent tooth. To ach ieve this, thetu be should describe between 30° and 45°of an Me of a circle whose centre is some­where in the midd le of the palate.

Let us assume tha t a righ t uneruptedcanine is pa latally pla ced (Fig. 2.6), then thistooth will be close to the m iddle of the pictur eobt ained in both films. However, in the firstpi ctu re, where the tube was d irected over thedesignated canine area of the ridge, the lateralincisor root will be on the right. If the cani neis also we ll fo rwar d, the re w ill be so me over­lap of the can ine crown an d the lateral incisorroot. On the seco nd picture, taken from the

23 21

2

23 21

fron t, the right lateral incisor root and thecro wn of the pa latal canine will be in the mid ­d le, superimposed on on e another to a muchgreater deg ree.

Jacobs (1986, 1987) enjo ins the obse rver touse the right eye in p lace of the x-ray tubeand suggests the useful exercise o f hold ing uptwo fingers vertically at eye level, with oneobscu ring the o ther. If the observer nowcloses th is eye and opens the other, h is or hernew vantage poi nt fo r inspection will haveresu lted in a visual separation of the two fin­gers. Th rough the left eye, the obscured fingerwill ha ve 'moved' to the left of the forw ardfinger, to become partially visib le. Trans­ferring this to the rad iographic context, in thesecond pictu re, the tooth furthest from thetube [l.e. the pala tal toot h ) will 'move' in thesame d irection that the X-ray tube has trav­elled from the first exposure.

This method is very useful in cases wherethere is a m inim al height d iscrepancy be­tween the erupted and uneru pted adjacentteeth (Fig . 2.5). However, when the canine ishigh and the periap ical view shows no supe r­im posit ion of the canine with the roots o f theerupted teeth, o r where the superimpositionis only in the apical area, then the overall pic­tu re may be very m islead ing and a differentmet hod of locali za tion should be used. Theperiapical view is d irec ted from above theocclusal p lane an d in an oblique downw ardand med ial d irection , which di stances thepalatal canine from the roots of the othe rtee th and makes it appear higher than theanatomy of the maxilla wou ld allow.

Tn the incisor region, an unerupted perm a­nen t incisor may be associated with one ortwo supernumerary teet h (meslodcns) . Theparallax method is insu fficiently clear in thesecases, because of the presence of two or threehard tissue entities in the bone, superimpo sedon the outline of the root s of the decid uoustee th and at vary ing heig hts in the alveolus.

Radiographic views at right-angles

Radiogra phic views may be taken at righ t­angles (Seward , 1968; Hunter, 198] ) to one

-RADIOGRAPHIC METHODS RELATED TO THE DIAGNOSIS OF IMPACTED TEETH 19

(.) (b) «)

Figure 2.7

(a) The trw lateral cephalometric radiograph shows both canines superimposed, ill a higher levelthan th., other Il'CIh.

Their axial inclination in the aotero-posterior plane is favo urable, with the crowns and "'pin'S apparontty normallylocated . (b) The pos tero-anterior cephalom etr ic radiograph shows the fwo camncs !'imilarl)' anguletcd, wifh their apicesin the line of thl' arch and thl' crowns dose.' to the mid line. From IhL~ Iwo films, we molY concl ude that the apices art.'ideally ploln-d an d that the long ""lOS of the It...·!h hav e a downward, mesi al and palatal incli nil(ion. (0;:) The pa no ram ic\ -i l' W of the same pa ti.'nl. Th., apF"'arancc of ca nines c!0S<' 10 the midline is very simil.u ttl that .......n on th.· pos tero­anterior ccphalomcutc radiog raph .

anothe r in various ways, bu t, for the met hodto be of value, it must be possible to deter­mine the exact o rien tation in space of both thefilm and the central ray, by obse rving otherstruc tures on the film. This requirement isvery difficult to satisfy when a v iew is soughtat right angles to the periapical view.

Standardization, w hat is requ ired is thestandard ization of views wit hin the confinesof a strict ad herence to the planes of space. Atrue lateral view (Fig. 2.7a) will give exact infor­mation regard ing both the antero-posterior andvertical location of an object, relative to otherstruct ures tha t may be seen both on that radi­ograph and clinically. It will no t g ive any clueto the bucco-hngue l (transverse-plane) pic­ture. A true occlusa l view will provide posi­tional information in bo th the antero­posterior an d transverse planes, but not thevertical plane. The third possibility is the truepostero-anterior view (Figs 2.7b,c), whichdefines the he ight (vertical plane) and the

bucco-Hnguel relatio nsh ip only. By combin­ing the resu lts of any two of these three films,three-d imensiona l localization may be accu­rately determined .

Translating these princip les into rad io­graphi c practice presen ts some difficulties.However, these arc not insur moun table and,insofar as they present the clinician withaccu rate posit ional visualizat ion of theunerupted tooth, they arc ent irely worth­while.

In the rnandibulnr posterior area, we havepointed ou t that the routine per iapi cal radio ­graph is also a true lateral view, with theX-ray tube po in ting at right-angles across thebod y of the mandible, in the horizontal plane.The height and mesio-distal position of abu ried tooth may then be accurate ly defined .The occlusal rad iograp h of this area isd irected at right angles to the occlusal plane,and adds the bucco-Hngual d imension tocomplete the three-d imensional picture.

THEORTHODONTIC TREATMENT OF IMPACTED TEETH2O ~=~===~== ===_'_

(. ) (b )

Hgure 2.8

The tru e la teral an d true occlusal view s, taken tog eth er, pro vide all the info rmation needed for an accura te positionalassessment of crown and root in the three planes of space. (ill The peria pical view (a tru e lateral in this case) of animpacted mandibular right second premolar shows the tooth to be tipped distally 60" from the vertical. with its incom­plete apex at the correct height and mesio-dis tallocaticn. (b ) The true occlusal view shows the crown oi the tooth to belingua l 10 the molar, and the apex 10 be in the bucco-lingeallme of the arch. The long axis of thc tooth, proceeding fromits ideally s ited i1f'l'J(, may be described as rising at a 30" an gle in a dis tal and lingua l direction, 10 oVl'rlap the mola rroots on the lingual side .

According ly. these two views will provideaccura te localization of the position ofunerupted tee th in th is area (Fig. 2.8).

For most orthodontic cases, the lateralcephalometric rad iogra ph is an essentialprerequi site and, aside from the routine mea­surement of angles and planes, this filmsho uld also be used to gather valuable infor­ma tion regarding the location of uneruptedteeth. The lateral cephalogram represents atrue lateral view of the skull, and, for the pre ­sent purposes, of the ante rior max illa in pa r­ticular (Fig. 2.7a). Altho ugh there arc manysupe rimposed structures on this area, the out­line of a canine may be clearly seen. Thedirection of the long axis of the tooth in thean tero-posterio r and ver tical planes may bedefined, together with the mesiodistal posi­tions of both crow n and apex.

If a cepha lometr ic radiograph is not ava il­able, the same view of the anterior maxillamay be obta ined on an occlusally sized film.This film is he ld vertically against the cheek

and parallel to the sagittal plane of the skull.The X-ray tube is d irected horizontally aboveand parallel to the occlusal plane from theopposite side of the face, an d at righ t-anglesto the film. The result is called the tangentialview and has the advan tage of simplicity.This view is particularly useful in monitor ingprogress in the resolution of impactedincisors during active treatment.

At the age at wh ich most pa tients first pre­sent wit h an impacted centra l incisor (around8- 10 years), the permanent canine teeth areunerupted and are located both well forwardand high in the anterior max illa. Thus, on thelateral cephalometric or tangential view, rightand left canines will be impossible to d ifferen­tiate ind ividually. The root s of the incisors, atthe same height as the canines, as well as thesuperimposed images of the more inferiorlyplaced crow ns of the erupted incisors anddeciduous canines, will all be indistinguish­able from one another and from supernumer­ary teeth that may also be presen t. For this

RADIOGRAPHIC METHODSRELATED TO THE DIAGNOSIS OF IMPACTED TEETH 21

Figure 2.9

A dilacerated cent ral incisor so-en in the lateral o.'phalo­mctri c rad iograph.

reason, the lateral view may be of limitedvalue in cases where there is obst ructiveimpaction. with minimal d isplacement. Whe ngross d isplacement is present, however, theoutline of the altered axial inclination and­height of the tooth can usually be delineated,despite the conside rable superimposi tion ofother tee th.

Nowhere is this view a greater asset thanwhen a dilacerated too th is presen t, since itseparates out this malformed too th, superi ­orly, from the roo t apices of the other teethand from the permanent canines, becau se ofits relative height (Fig. 2.9). Furthermore, itsmorphology may be seen to bes t ad vantagefrom this aspect, wh ich allow s definitive andaccurate diagnosis of the condition to bemade, together with its precise relations vis-a­vis surrounding structures. The tangen tialview sho uld be considered an essentialrequirement in radi ographically record ing thedtlaccra tcd centra l incisor.

For maxillary can ines, the lateral view isextremel y useful. It should be rememberedthat most impacted maxillary canines ared iagnosed in the full pe rmanent dent ition,when all the othe r tee th wi ll have erup ted.This dema rcates the canine at a higher levelthan the o ther tee th.

A postero-anterior cephalometric film isused less rout inely in ort hodontics, bu t it

offers the clinician the oppor tunity to viewthe maxilla in a d ifferent plane, the truepostero-anterior view (Fig. 2.7b), which is atright-angles to the latera l cephalogram. Theoverlap of structures of the base of the skulland the maxilla renders detail of ind ividualteeth less clear, but a good pos tero-anteriorradiograph will show the height of bo th thecrown and the root of a mark ed ly displacedtoo th, as with the lateral fil m. This view alsoshows whether the roo t apex of an ectopicpos terior too th is in the line of the arch andhow far the crown is deflected in the pa latald irect ion . The bucca-lingual tilt of the longaxis of the too th will be plainly visible (Fig.2.10). However, the view is less practica l inthe mandible, where the body is oblique tothe cen tral ray. There is usually excessiveoverlap, mo re radio-opaque bone an d diffi­culty in discerning even ma rked ly bucca­lingually displaced teeth.

An occlusal projection of the anterior max­illa (Fig. 2.3) offers the possibility to view inthe third plane of space, at right-angles toeach of the two earlier rad iographs, and torecord the position of the displaced incisor orcanine without overlap . However, for it to beof greates t value, it is important to project theX-ray beam through the lon g axis of the maxi­llary teeth, as jus t described.

Any two of these three views (the lateralcephalogram or tangential view, the postero­anterior cephalogram and the true occlusal)will provide complete information reg ard ingevery aspect of the height , bucco- ling ua l andmesio-dis tal location of the crown, the root,and the degree of tilt of the long axis of theimp acted tooth and its relation with neigh­bour ing teeth. The postero-anter ior andocclusal views, how ever, arc 110t always asclear as is desirable, and they may need to berepeated or discarded . The lateral cephalo­metri c or tangential views in a cast' of bilat­era l canine imp action may crea te confusion,since one canine will be superimposed on theother and distinguishing them may be a prob­lem, although othe r views will usually facili­tate di fferentiation. Two identically orien tedand superimposed canines (Fig. 2.7) will obvi­ously not need to be differentiated.

Fr"om these aspects, it is very easy to bu ild

22

(.j

« j

THE ORTHODONTICTREATMENT OF IMPACTED TEETH

(b j

Fig ure 2.10

(e.b] Extracted portion of the lateral and postero-ant erior cephal o­metric views, to show an impacted max illary left second premolarto be loca ted with its apex in the line of the arch, but superiorlydi splaCl.·..t Th{' cro w n is displaced pala tally, close to the m id lineand the long axis is strongly palatal, slightly dow nward andslightly distal. (c) The periap ical film gives the misleading appear­ana' of the crown being dis placed superiorly and anteriorly.(Courtesy of Dr I Gill is.)

up a three-d imensional picture of the exactposition and angulation of the im pacted toothand to define the type of movement that willbe necessary to b ring the tooth into align­ment. When building this compos ite menta lreconstruction of the position of the un ­erup ted too th in space, the desig n of theappliance needed to resolve the impaction issimplified and fewe r surprises are likely to beencountered . It is, however, an important p re­requisite in all these cases to examine a peri­apical view of the tooth, to eliminate thepossibility of local pa thology, which could bemissed on the extra-oral views.

CT SCANNING

Recen tly, the usc of computed tomogra phy(CT) scanning has been suggested (Ericsonand Kurol. 1988a,b) for identifying the exa ctposition of the palatally impacted canine, par ­ticula rly when root reso rp tion of the lateralincisor is suspected (Ericson and Kurol. 1987).cr scann ing is a method in which clear serialradiographs may be taken at grad ua teddepths in any part of the human body (Fig .2.11a). At the same time, this techniqueallows the elimination of the superi m positionof othe r stru ctu res that we ha ve seen w ill

RADIOGRAPHIC METHODS RELATEDTO THEDIAGNOSIS OF IMPACTEDTEETH 23

(.)

(d )

(bl

(el

(-)

Figu re 2.11

(a) The lateral skull r,ld iogr,l ph shows the direction and separation of the indiv id ual CT "slices', (b-e) These sectionsdt'p ict most clearly tht' midline slIpt' m umerar y loath and its rel,l tion~hip to the adja cent teeth in all three pl ant'S ofspace. (Co urtt'Sy of Dr 0 Eiscnbud.]

obscure the image of the object tha t we areattempti ng to view in trad itional radio­graphy. In recons tructive dentistry, thismethod has been developed to allow accura teplacement of implants (Schwa rz et al, 1989).Although it has excellent potential for thediagnosis of the position of impacted andsupern ume rary teeth , the large dosage ofrad iation is difficult to justify for all excep tthe exceptional case.

By viewing seria l rad iographic 's lices' ofthe maxilla (Figs 2.11b-c), the relationship ofthe impacted too th to adjacent teet h, in allthree planes of space, may be accuratelyassessed , as can the positions of CTOwn andapex and the inclination of the long axis of the

tooth. In the following chapters, we sha lldescribe how the relative difficulty of br ing­ing these teeth into their proper posit ion isdepe ndent on advance knowled ge of theexact positions of bot h crown and root apex.We sha ll conclude that variations in root apexdisplaceme nt, in particular, prejudice both theability of the orthodontist to complete theexercise and the periodontal prognosis of thetooth, when the treatment is finally com­pleted . The method may also give accurateinformation regarding ear ly root resorption,pa rticula rly of the buccal and palatal su r facesof the roo l. Th is may not be possible to d iag­nose by any o ther me thod , prior to treatment.It therefore makes sense that for those

24

pat ients in whom there is a suspected dis­placement of the long axis of a tooth, dueto an abnormal orientation of the rool apexor the presence of root resorption (Ericsonand Kurol, 1988b), the use of high-resolutioncomputed tomography should be considered.

Although CT scanning units are relativelyfew and ima ging is expensive, their us e isincreasing. and they are now more freelyavailab le to the orthodontist in p ractice . Itmay still be d ifficult to just ify us ing themethod on a routine bas is for the occasionaland more straightforward case with one ortwo impacted teeth . However, its use in casesof multiple impactions, particu larly cleidocra­nial dysplasia, has much to offer in the accu­rate pla cing of the very large numbe r ofimpacted teeth, both at the treatment plan­ning stage and the subsequen t surgica lphases.

REFERENCES

Ericson S, Kurol J (1987) Rad iographic exami­na tion of ectopically erupting maxillarycanines. Am I Orthod Dentojac Orthop 91:483-92. .

Ericson 5, Kurol J (1988a) CT d iagnos is of

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

ectopically eru pting maxillary canines - acase report. Elir I Orthod 10: 115-20.

Ericson S, Kurol J (1988b) Resorp tion of maxil­lary late ral incisors caused by ectopic erup­tion of canines. Am I Orthod Dentojac Orthop94: 503-13.

Hunter S6 (1981) The radiographic assess ­ment of the une rupted maxillary canine. BrDent 1 150: 151-5.

Jacobs SG (1986) Localisation of theunerupted maxillary can ine. AI/sf r Orthod 1 9:313-16.

Jacobs SG (1987) Exercises in the localisationof unerupted teeth . Austr Orthod J 10: 33-5,58- 60.

Mason RA (1982) A Guide to DentalRadiography, 2nd edn. Wright PSG, Bristol.

Ong A (1994) An altern ative techn ique to thevertex / true occlusal view. Am J OrthodDentcfac Orthop106: 621-6.

Schwarz MS, Rothman SLG, Cha fetz N,Rhodes M (1989) Computed tomography indental implantation surgery. Dent Clin N Am33, 555-97.

Seward GR (1968) Radiology in general den­tal pra ctice. IX - Unerupted maxillarycanines, central incisors and supernumer­aries. Br Dellt / 115: 85--91.

3 SURGICAL EXPOSURE OF IMPACTEDTEETH

In collaboration with Professor Arye Shteyer and Professor Joshua Lustmann

CONTENTS • Aims of surgery for impacted teeth • Surgicallntervenlion withoutorthodontic treatment • The surgical elimination 01 pathology • Buccal lyaccessibl eImpacted teeth • Part ial and fu ll f lap closure on the palatal side • A con servativeattitude to th e dental follic le • Cooperation between su rgeon and orthodontist• The team approach to attachment bonding

AIMS OF SURGERY FOR IMPACTEDTEETH

For impacted thi rd molars, treatment alterna­tives and opportunities for choice are few,and. in the majority of cases, extract ion isad vised . However, for othe r impacted tee th,this is not so, and seve ra l lines of treatmentmay presen t (McDonald and Yap, 1986).Neverth eless, in the past, the decision as tohow a particular impacted tooth should betreated was most often decided by the oralsurgeon, who also, by and large, decide dupon and stage-managed the alternatives.This situation has cha nged in recen t years.

Prior to the 1950s, most orthodo ntists wereunprepared to adapt their skills and ingenu­ity to the task of resolving the impaction ofmaxillary canines and incisors. Accord ingly,the or thodo ntists them selves referred patientsto the oral surgeon , who would decide if theimpacted too th could be brought into thedental arch. Where the circum stances werepotentially favourable, the tooth wo uld besurgically exposed, and, when the surgicalfield was displayed fully, the surgeon wouldmake his assess ment of the prognosis of the

case, decide and act solely in accordance withhis own jud gemen t. In this way, man y po-­tentially re trievable impacted teeth wereextracted.

There a re no surgical methods, other thantransplantation . by which positive and activealign ment of an impacted tooth may be car­ried out. The best a surgeon may do is to pro­vide the optimal env iron ment for normal andunhindered eruption and then ho pe and praythat the tooth will oblige. With this in mind,therefore, those teeth that were consideredwor th trying to recover we re wide ly exposedand packed with gauze soa ked in White­he ad 's varnish, to protect the wound duringthe healing ph ase and to prevent reheating ofthe tissues over the tooth. For a varie ty of rea­sons, several oth er steps were taken, depend­ing upon the preferences and beliefs of theoperator, with the aim of provid ing 't hatextra something ' that wo uld improve thechances of spontaneous eruption still fur ther.These measures were often very empirical innature, and included one or mo re of the fol­lowing:

(a ) clearing the follicula r sac completely,including in the eEJarea;

26 THE ORTHODONTICTREATMENT OF IMPACTED TEETH

(b) clcan ng the bmw aro und the too th, downto the eEJ area, to dissect out a nd free theentire crown an d the corona l porti on ofthe roo t of the Impacted too th;

(c) 'looseni ng up' the too th, by subluxa ting itwi th an eleva tor;

(d) bone-channelli ng in the desired direc ti onof movement of the too th;

(e) pocking g,l uZC or hot gutta pe rcha in tothe area of the CEl , und er p ressure, inorder to apply force to deflect the crop- ~

tion pa th of the tooth in a particula r d irec-no n.

(.1

Figuree 3.1

(,1) A lo·yt'.u-ul,l k nl,llt' exhibitsan Ullt' Tuple,.I maxillaryldt canine, which h,IS been pn'St'n l in thi" povirion fur 2yt'.lTh MId h,IS not progres sed. (b) The loo th W,lS ,'xpf)';cd,an d Ih,· flap , whi ch co ns ist,,,,l of thickened mU(O"'l. wasapically repo sitioned . (c ) At 9 mon ths post-surgery. the

t"" th h,l" erupted nn rm"ll y. (Cour t,'!'>y of L Shapira.)

lei

W e COIllC a c ros s Cil SCS in which th e on ly clini ­cal problem relates to th e impacted tooth, theocclusion an d nllgnmcnt being otherwiseacceptable. For these pa tien ts. the followingquestion needs to be addressed : What surgi­cal methods MC available that may beexpected to pro vid e a more or less completesolu tion , wi thou t out s ide assistan ce? To be ina position to answer this question, it is neces­sary to provid e a d escription of the positionof the teeth that wi ll respond to this kind oftreatment .

SURGICAL INTERVENTION WITHOUTORTHODONTIC TREATMENT

In those years. few patients were referred tothe o rthodontist until full eruption had beenachieved and the tooth then needed to bemoved horizontally into line with its ne igh­bOUTS. Up to that point. the problem was con­sidcrcd to be w ithin the realm of the oralsurgeon. In many cases. 'success' in achievingthe eruption o f the too th was pyrrhic andoften subordina ted to failure of .1 d ifferentkind . namely the period o ntal condition of thenewly eru p ted tooth and its poorer su rvi valpo ten tia l - its prognosis. Th is was theinevitable resu lt o f the aggressive and overenthusiastic su rgical techniques that had bee nus ed. which typ ically left the too th with an (hIelongat ed clinical crown, ,1 lack of attachedgingiva an d .1 red uced alveol ar cres t heigh t(Odenrick MId Modcc r. 1978; Boyd , 1982,19M; Becker ct al.1983; Kohavi ct .11, 1984a, b).

SURG ICAL EXPOSURE OF IMPACTED TEETH

(b)

Figure 3.2

(a) Soft tissue impaction of max illa ry centra l incisors. (b)Apical reposi tioning (If bo th buccal and pa latal flap s toleave the incisal edges exposed . (Courtesy of Professo r JLustma nn.)

Exposure only

A superficially pla ced too th, palpable beneaththe bulging gum, is an obvious candidate.This type of tooth may be seen in the maxil­lary canine a rea (Fig. 3.1), but also in themand ibu lar premolar area (sec Fig. 1.8) andthe maxillary centra l incisor area (Fig. 3.2),usually where very early extraction of thedeciduous predecessor was performed wh ilethe immature permanen t tooth bud was stilldeep in the bone and unready for eruption.Healing occurred , and the permanent teethare unable to pe netrate the thickened mucosa(Dibiase, 1971; And reasen and And reasen,199~) . Removing the fibrous mucosal cover­ing or incising and resutu ring it to leave theincisal edges exposed (Figs 3.1a and 3.2b) will

Figure 3.3

Following exposure and packing, tlw tooth has eruptedspontan<-'(lusly. bu t thO;' bon... l...vel is compromiso."d.

generally lead to a fairly rapid eruption of thesoft tissue impacted. too th, particularly in themaxillary incisor area. The mo re the toothbulges the soft tissue, the less likely is a rebu r­ial of the tooth in healing soft tissue and thefaster is the e ruption .

Exposure with pack

Taking this one step fur ther, we can SI,.'C that aless super ficial tooth req uires a more rad icalexposure procedure, and may need a pack topreven t the tissues frum reheeling over thetoo th. While the surgeon may be rewa rdedwith spon taneous eruption, th is will takelonger, and a compromised per iodo ntal resultshould be expected (Fig. 3.3).

We have defined over- retained de ciduousteeth as teeth still present in the mouth whenthe ir permanent successors have reach ed astage of development that is compa tible withtheir full eru ption. These decid uou s teethma y then be considered as obs tructing thenormal development tha t wo uld be expectedto procee d in their absence, The deciduo usteeth should be extracted, bu t prov isionsho uld be mad e to encourage the pe rmanentteeth to erupt quickly. Many of these perma­nen t teeth wit h dela yed eruption arc obnor­mally low in the alveolus, and Me in danger

27

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH28~~----------'------------'----

of being rebu ried by the healing tissue of theevacuated socket of the deciduous tooth.According ly, the crowns of the teeth shouldbe exposed to their widest d iameter an d asurgical o r periodon tal pack placed over themand su tured in p lace for 2- 3 weeks. Th is willencou rage epi thelializ ation down the sides ofthe socke t and , generally, pre ven t the re-fer­mation of bone o ver the unerupted toot h.

Exposure with pressure pack

brought abou t an improvemen t of the posi ­tions of the grossly displaced teeth, togetherwith an improvement of the bony defect thatw ill be ev ident in the anatomy of the alveolarbone in the area, which may take ma nymonths to occu r. Duri ng th is time, the psy­cho log ical preparation of the patient for theproposed or thodont ic treatment may beund er taken, which mu st begin with seeingpo sitive results from a preventi ve dentalhealth programme aimed at elim inating ma r­gina l gingival inflammation and redu cing thecaries incidence for that patient. .

Mild mesial impaction of a mand ibu lar sec­ond permanent molar be neat h the distalbulbosity of the first permanent molar is acondition that often responds to surgicalinterven tion and packing on ly. Th is involvesexposure of the occlusal su rface of the toothand the deliberate wedging of some form ofpack in the area between the two teeth andlea vin g it there for two o r three wee ks.Duri ng this time, the pressure w ill often suc­ceed in eliciting a di sta l mov ement of theimpacted molar, which may then erupt morefreely whe n the pack is removed . The degreeof con trol available to the operator in judgingthe amo unt of p ress ure applied and theextent to which the pack interferes periodon­tally is minimal, an d lasting da mage to theperiodontium is likely. Success in bringingabout an improved position of the too th maythus not be matched by the health of its sup­po rting structures in the final analysis.

THE SURGICAL ELIMINATION OFPATHOLOGY

Soft tissue lesions

In Ch ap ter 7. we sha ll refer more specificallyto benig n tumours. Surgical treatment is theonlv trea tment tha t is indi cated for these con­diti'ons in the first instance. This should beperformed without delay, if only for reasonsof obtaining biopsy material to confirm theinnocence of a ten tat ive diagnosis. Ortho­dontic treatm en t should be suggested then ­bu t begun only after a filling-in o f bone has

Hard tissue obstruction

Obs tructive impaction invi tes the logical stepof rem oving the offe nd ing body causing theno n-eruption. On many occasions, this is pe r­formed by the su rgeo n, withou t recourse toorthod ontic assi stance, and enjoys a varyingdegree of succes s. ln Chap ter 5, we sh,111 referto the re liability of spontaneous erupti on,follow ing the various surgical proceduresinvolved in the treatmen t of impactedinciso rs. For the presen t d iscussion, we mustrecogni ze th at there is a significa nt number ofcases in which e ruption does not occur in areasonable time frame .

Undoubtedly, the position of most un­erupted teeth improves with the passage oftime, following the removal of the obst ruc­tion, be it a supern umerary tooth, an odon­tome, res id ual decid uous roo ts or an infra­occluded primary tooth. However, many ofthese teeth do not erupt without assistance,because of local dis turbances caused by therecently removed obstruction and the healingtissues.

A hard tiss ue body occupies mu ch spa ce,and may cau se a gross d isplacement of thedeveloping tooth bu d of the norm al too th,both in terms of overall di stance from itsp lace and in that the o rien tation of its longaxis is also deflected. Thus the root or thecrown of the tooth may be deflected mesially,distally, ling ua lly or buccally , comprom isingits cha nces of spontaneo us eruption. Ab­normally sha ped root s may develop in the

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SURGICAL EXPOSURE OF IMPACTED TEETH

cramped circumstances in wh ich they findthemsel ves, between the disp lacing influenceof the pathological entity an d the ad jacen tteeth, on the one ha nd , and the floor of thenose or lower bo rde r of the mandible (Beckerand Shochat, 1982), on the other.

Non-eruption disturbs the eruption patternof the ad jacent teeth, which then assume abnor­mal relationships to one another, usually char­acterized by space reduction and tipping. Thisthen provides a secondary physical imped i­ment to the eruption of the impacted tooth.

tntrsocclusion

As we sha ll discuss in Cha pter 7, infra­occluded permanent teeth are usu ally anky­lased to the surrounding bone, and, as such,cannot respond to orthodontic traction. Inmany cases, the ankylosed area of root isminute, and may be easily bro ken by a delib­erate but gentle luxation of the tooth. This isusually performed with an eleva tor or extrac­tion forceps, and is done in such a way as toslightly (very slightly ) loosen the rigid con-

(. )

nection of the bony union, which is unbend­ing. The tooth is not remo ved from its socket,nor is the aim even to tear the pe riod ontalfibres. The purpose is to retu rn the tooth tothe same degree of mobility that is cha racter­istic of a normal tooth.

Unfo rtunately, the fate of the too th that hasundergone this procedure is usually a reheal­ing and reattachment of the ankylot ic connec­tion, leading to a return to the originalsitua tion. Accordin gly, th is approach canonly be successful if a cont inuously activetraction force is applied to the tooth from thetime of its luxation. This force may then act tomodify the rchealing of bone, du e to the dis­tractio n osteogenesis (Ilizarov et al, 1980;Altuna et al, 1995) that it causes. If the rangeof force is small and loses its potency betw eenvisits for ad justment, reankylosis will result.Thus, to be effective, it must be of sufficientmagnitude to cause distracti on and of suffi­cient range to remain active between one visitfo r ad justment and the next. The risk is that apoor biomechanical auxiliary , insufficientforce levels or missed appointm ents maycause the exercise to founder, owing to re­establi shm ent of the an kylosis bridge.

(b )

Figure 3.-1

(al A high buccal canine exposed by circular incision of the sulcus mucosa . (b) Following alignm en t. the oral mucosa isallached directly to the gingi va. (Courtesy of Dr G Engel.)

THEORTHODONTIC TREATMENT OF IMPACTEDTEETH30 ...:...:=...:...::.:..:....:...: _

BUCCALLY ACCESSI BLE IMPACTEDTEETH

There are fou r met hods ava ilable to resolvean unerupted toot h that is on the bu ccal sideo f the ridge and high in the sulcus. Thcse areas follows.

1 A circular incision

This may be made in the sulcus mucosa,immediately over the crown, to expose thebony crypt immed iately beneath . In order todo this, the enti re su rgical procedure wouldinevitably be sited above the attached gingiva(Fig . 3.4).

From the su rgical point of view, suitableaccess will have been provided to allow thebonding of an attachment. From the ortho­dontist's standpoint. the application of lightextrusive forces of good ra nge presents noparticular d ifficult ies, an d red uction of theimp action may be very rapid.

Whilst this may satisfy both su rgica l andorthodontic demands, the periodon tic resultwill be poor, and there will be an elongatedclinical crown. The band of attached gingivawill be tu rned palatal to the aligning too th,which could create a factor for buccal posi­tional rela pse at the end of trea tmen t. On thelabial sid e, the too th w ill be inves ted with thethi n o ral mucosa, which offers a poor long­term prospect under cond itions of normalfunc tion for the fully corrected canine.

In many of these cases , eruption may occurnaturally, with the tooth emerging throughthe su lcus mucosa and above the attachedgin giva . Prompt treatmen t will be needed ifthese teeth Me to acquire a normal periodon­tal environmen t, wh ich will d ictate p re­empting their eruption . The circular incisionmethod provides no solu tion to th is.

2 Apica//y repositioned surgical ffap

This method, ., recog n ized and accep ted pro­cedure in pe riodontics, was first described inthe contex t of surgical and orthodontic treat -

men t of uneru pted teeth by Vana rsdall andCo rn (1977). In their method and in theabsen ce of the deciduous can ine, a muco­ging ival flap is raised fro m the cres t o f theridge that includes attached gingiva (Fig. 3.1).If a decid uou s canine is p resen t, the flap isdesigned to include the entire a rea of buccalgingiva that inves ts it, and the deciduoustooth itself is extracted . In eithe r case, the flapis detached from the underly ing hard tissuesome wa y up into the su lcus , to expose thecanine. The flap is then su tu red to the labialside of the crown of the permanent canine, tocover the denuded pe riosteum and overlyingthe cervical portion of the crown, while theremainder of the crown remains exposed .Subsequent eruption of the too th is accompa­nied by the healing gingival tissue, and, whenthe too th takes up its final positi on in thearch, it will be found to be invested with agood width of attached gingiva.

When left unt reated, palpable uneruptedtee th may take ma ny months to breakthrough the mucosa and reach their finalpositions. Whe n an apically repositioned flapis pe rformed , eruption is speeded up. Add i­tionally, with the sutu red so ft tissue applyingsome pressure on the buccal side of the toothand assuming there to be space in the imme­diate vicinity, a bu ccal d isplacemen t may bespo ntaneo us ly red uced.

If the unerupted tooth is very h igh , the sur­gical flap, wh ich stretches from belo w theattached gingiva on the cres t of the ridge or atthe free gingiva of the deciduou s tooth up tothe depth of the sulcus, would be excessivelylarge. Under these circums tance. the proce­dure is no t recom mended, since the ap icallyrepositioned flap wou ld then leave a widearea of the labial bony plate unnecessarilyexposed to the oral environment.

In a more recent study, Vermette et al(1995) found several drawbacks in relation tothe aesthetic and period on tal results of theapically repos itioned flap technique for buc­cal canines, wh ich had no t been previouslyreported. Tn uni laterally affected and trea tedcases, the clinical crown length was greaterthan the unt reated control side and anuneven and unaesthetic ging ival ma rgin wasoften produced (Fig. 3.5). There was also a

SURGICAL EXPOSURE OF IMPACTEDTEETH

Fig uno 3.5

Uneven and un aesthetic g ingival margin, bands of gingi­va l sca rring and a long d in i(al (TOWn, followin g api (alrepositionin g of the flap cov ering thi s form erly buccallyimpacted ( an ine.

degree of attachment loss and bone loss onthe labia l surface, whi ch was considered aspossibly related to an increased. poten tial forplaque accumulation that the procedureseems to encourage.

Vermette et al (1995) also reported a verticalor thodon tic relapse in 61% of the teeth thathad been erupted using orthodon tic appli­ances, after trea tment had been completed .They speculated that the reason for this isthat, follow ing the api cal repositioning, thegingiv al tissue heals to the adjacent mucosa,producing soft tissue bands of gingiv al scar­ring. As the toot h is pu lled Inosally, th ismUCOS<l is stretche d down with it, towards thealveola r crest. This then leads to a relapse ten­dency when the forces a rc released. Howeve r,the per iodonta l attachment was unaffectedwhen comp ared with the unoperated controlside.

Neve rtheless, an important advantage ofthe me thod is that the buccally imp actedcanine is exposed to the oral environment,and remains accessible for attachment bond­ing. In some cases, where orthodontic treat­ment is no t needed for other problems, theprogress of the too th may be followed formany mon ths, unti l full erupt ion will have

occurred, without the use of appliances (Fig.3.1). In others, an attachment may be bondedby the ort hodon tist at any app rop riate laterda te and active extrusion subsequentlyundertaken .

3 Full flap closure

This was proposed by McBride (1979), and isa procedure tha t may be used rega rdless ofthe heigh t of the canine. A buccal surgical flapis raised as high as is necessary to expose theunerupted canine. An attachment is thenbonded to the tooth. and the flap is fullysutured back to its former place. A twistedstainless steel ligature wire that has beenthrea ded throu gh the attachment is thendrawn inferiorly and throu gh the suturededges of the replaced flap, at the cres t of theridge, or th rou gh the socket vacated by theextracted deciduous canine.

Spontaneous eruption is less likely to occurthan when the tooth remains exposed, follow­ing apical reposition ing, and act ive or thodon­tic force will probably need to be applied tothe tooth to bring abou t its eruption. In thismethod, the too th erupts toward and throughthe attached ging iva area, which thenbecomes attached to the tooth and the sur­rounding alveolar process.

This d osed-eruption method compares fav­ourably (Verme tte et al, 1995) with the api­cally repositioned flap method describedabove. The full flap closure method (closederuption technique) shows no ten dency for anapical and uneven gingival posit ion, nor doesit produce a long clinical crown . There is noloss of att achment on the buccal aspects, noris gingival scarring prod uced with thismethod, and the pe riodonta l attachmen t iscompletely norma l.

A fur ther and pa rticularl y significant d if­ference between the two methods of surgicalexposure of the buccal canine repor ted in thiswork was that in the full closure method,the re was no vertical relapse of the treatedcanine follow ing the completion of treatmen t.However, the closure of the flap at the end ofthe surgical stage dictates the necessity for the

31

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH32 .::.:.-=-=.::.:....:..:.::..::.::.:.-"-==--'-=-"-=.::.:..::.:..::..::.=..::= CC

Figu re 3.6

Buttonholing.

p lacement of an attachment, while the toot h isvisible and in the surgeon's operatory. It can­not be left until a subseq uent visit.

The method has unequivocal advantagesover the apically repositio ned flap me thod, andthese have been attributed to the close similar­ity of the conditions brought about by full flapclosure to those associated with normal too theruption (Crescini et at 1995). On the basis oftheir resul ts, Vermette and co-workers questionthe indications for the continued usc of theapica lly repositioned flap method .

A significant problem with the closed eru p­tion techniq ue is so metimes caused by a poorcho ice of bonded orthod on tic attachmen t.Since the midbuccal position o f th is too th iseasy to expose and to bond to, the orthodon­tis t may be tempted to use a conventionalo rthodontic bracket in this ins tance (Wong­Lee and Wong, 1985). Becau se of the buccalpro minence of the too th, the lack of buccalbon e and the rela tive tigh tness of the replacedflap, damage may be caused to thi s muco­gin gival tissu e by the bu lk of wid e and high­p rofile conven tional bracket s (sec Fig. 4.4),which may lead to a breakd own of the over­lying tissue , to cause a dehiscen ce or even'bu ttonholing' (Fig . 3.6). Once again, there­fore, the use of an eyelet offers s ignificantadvantages due to its more modest di men­sions and lower pro file, at least u ntil th e toothhas erupted and been b rou ght into closepromixity to the labial arch wirc.

4 The relief of crowding to reducecanine displacement

If the d ispl acemen t of the canine has been dueto crowding then it follows that spontan eo usimprovement of th e position of the caninemay well occu r if the crowd ing is eliminated.

Time ma y no t be on the side o f the clinicianopti ng for th is approach, s ince the too th maye rupt th rough the oral m ucosa if delay isincurred. Nevertheless, for the case in wh ichthis ap proach is to be used, a fu ll case analy­sis is req uired, leading to a d iagnosis andtreatment plan for the overa ll m alocclusion . Ifthe crowd ing is to be d ispe rsed by d istalmovemen t o f the molars, it w ill take it longertime before space is avail able in the caninereg ion, wh ich is the most common area wherethis type of problem occu rs. Consider abled elay mu st be expected while the treatment isproceed ing, before spontaneous improvementof the canine pos ition ma y be seen. On theothe r hand, a p remolar extraction will pro­vide immedia te relief of the crowdi ng and anexcellent opportunity for a self-correction o fthe buccal d isp lacement and, with it, thedisappearance of th e poten tial pe riodontalhazard .

PARTIAL AND FULL FLAP CLOSURE ONTHE PALATAL SIDE

Occasionally. impacted teeth that a re locatedon the palatal side are palpable imm ed iatelybeneath the pa la tal mucosa . The surgicalremoval of a circu lar section of the ove rlyingmucosa (sec Fig. 6.26) to leave the toot hexposed is tempting and has obviou s advan­tages. Howeve r, the palata l mucosal coveringis ve ry th ick and will leave a broad cu t sur ­face, which w ill tend to close o ver u nless itsedges are more radically tr im me d back andthe dental follicle removed . Thus, for a deep lyplaced tooth, the exposure will ad ditionallyneed to be ma int ained using a su rgical pack.This type o f surgical approach will thereforeleave the tooth with a soft tissu e defici encyand a long clinical crown at the completion ofthe orthodontic alignme nt.

SURGICAL EXPOSUREOF IMPACTED TEETH

As we have described for the buccal side,full flap closu re on the palatal side requiresattac hment placement on the exposed tooth,p rior to resutunng. This then allows the too thto be exposed with the minimum of tissueremoval and consequen t su rg ical trauma.When this is done and given appropriateor thodontic mechanics, the final result w illshow that the bone support for the tooth,as well as the hea lth an d appearance ofthe mu cogtngival tissues, are at their best.The accumulated ev idence that has beenpresented in the va rious clinical compa riso nsof su rgical methods of exposure (Heaney andAtherton, 1976; Wisth ct al, 1976; Odenrtckand Modeer. 1978; Boyd, 1982, 1984; Becker etal, 1983; Kohavi et al, 1984a,b; Crescini et al.1995; Vermette ct al, 1995) provid e a scientificbasis to recommend the full flap closu reapproach over any other.

A CONSERVATIVE ATIITUDE TO THEDENTAL FOLLICLE

The den tal sac or follicle develops from ameso dermal condensation of cells on theouter surface of the exte rnal enamel epithe­lium of the enamel organ of a formi ng tooth,into a fibrova scu lar capsu le. The follicle hasan inner vascular p lexus th rough which theenamel organ is supplied with nutrients d ur­ing growth, and an outer vascu lar plexus con­cerned with en larg ing the bony crypt inwhich the toot h germ lies. The follicle encom­passes the en tire tooth germ, and, as the roo tportion of the toot h is formed , the adjacentpar t of the follicle transfor ms to become theperiodon tal membrane, connecting the cemen­tum cove ring of the developing root to thedeveloping alveolar bone.

The enamel cu ticle is made up of a kerati­nous de posit from the ameloblast s and thereduced enamel epi thelium, and is con tinu­ous wit h Hcrtwtg's epi thelial root sheath .Th is separ ates the crown of the tooth from thefollicle, from which the roo t develops andcementum forms. Becau se of th is separa tionbetween follicle and enamel, cementum is notformed on the crown of the tooth.

Eruptive mov ements b ring the tooth folliclein to close contact with the o ral mu cosa, the irep ithelia fuse, an d the too th thus breaksthrough an epithelium-lined open ing. Aseruption p roceeds, the remaind er of the folli­cle everts and becomes tu rned ' insi de out' ,with the red uced ena mel ep ithelium formingthe gingiva l cuff and the most superficialpoint of attachment.

Whe n im pacted w isdo m teeth a re removedsurgically, the dental follicle is always care­fu lly d issected out to p reven t the possiblelater occu rrence of cys ts that may arise fromres idual follicle epitheli um. However, when atoo th is exposed, only its su rround ing folliclehas an im portan t function to fulfil. This d if­ference in attitude to the follicle of a toothcommitted for extrac tion, compared wi th thatof a tooth that is to be exposed and subse­quently erupted into the mou th, is basic andimportant to understand.

From stud ies o f the cau sation of externalcrown resorption of long-standi ng bu riedtee th, it has been found that pathologicalchanges occu r in the follicle su rroun di ng itscrown (see Fig. 6.11) - changes that havebrough t the enamel su rface in to d irect con tactwith the su rround ing tiss ues (Blackwood,1958). It is easy to d raw a pa ra llel betwee nthis cond ition an d the artificially producedenvironmen t of an impacted too th tha t hasbeen su rgically exposed and has subse­quently become rebu ried in the tissues. If, forwhatever reason, the toot h docs not eruptspontaneously, the re will be long-term d irectcontact between the tissues and the en amel ofthe tooth .

In clear ing the su rround ing tissues for thepurpose of crea ting all adequate opening,which w ill not eventua lly close down, thesurgeon will, gen erally , deliberately and com ­pletely remove the follicle surround ing thetooth (Fig. 3.7). Should spontaneous eruptionthen occur, the oral ep ithelium will growdown the sides of the opening. It will thenattach more apically on the tooth than no r­mal, and a comprom ised ging iva l attac hmen twill resu lt. The erupted too th will have alonger clinical crown an d red uced alveol arcres t heigh t.

The ap plication of or thodontic tra ction on ly

33

THEORTHODONTIC TREATMENT OF IMPACTED TEETH34 ----------------=------ --

I' )

'b'Figure 3.7

(a) A Ieft impaclt>d ma\iIIar)' central incisor has been",xp(l~d and the entire follicular Sole removed, prior tocemcntmg a band (case trea ted before the advent of directbrac ket bonding to e tched crl,'mcl). (b) Two }'l'ars post­treatment shows pOO l' F>in~i\',l l conte nt an d positionaldeterioration.

requi res an ope nin g in the foll icle that islarge enough for the attachment to be placed,while the rest of the follicle may be leftinta ct. The surgical flap may then be fullysutured back and the wound completelyclosed. O rthodontic tract ion bri ngs the too thtowards the oral cav ity, and the follicle fuseswi th the or al mu cosa, to mim ic no rmal erup ­tion. Th is lead s to the est ablishment of a nor­mal gingival a ttach me nt (Crescini et al, 1995).

A new loo k mu st be taken at the surgicalp lan fo r the exposure of unerupted teeth. Ifbon d ing will not take p lace at surgery th en aw ider expos u re mus t be performed and a su r­gical pac k may 0I..'Cd to be placed, in order top revent the reclost ng of the wound. It is

im portan t to av o id the over-zealous su rgicalremova l of the foll icle and d amage to thecemcnto-enamel junction area by forcefu lplacement of the pa ck, a poorer resu lt sh ou ldbe expected . Attach me nt bond ing m ust sub­seque ntly be pe rformed at a convenient tim eaft er pa ck removal, at the orthod onti s t' sleisure. Howeve r, at this time, the heal ing andswollen g ingival tiss ue su rrou nd ing theexposed too th will be tender, will bleed wi thminimal p rovoca tion and will be coveredwith plaque, s ince effective toothbrus hing isu nlikely to have been po ssible.

A wide flap des ign has the advantage ofdisplaying the area of bone covering thetoo th, which is helpful in identifying of theexact site of the too th . A canine too th buriedin a bony crypt in the palate will alter theshape of the palate inferiorly by creating adistinct bu lge of thinned bone, and this willbe all the more obvious if m uch of the sur­ro un ding bone is also vis ible . Th is is just astru e in the labial pla te of the maxilla an d inthe bu ccal or lingual pla te of the mand ible,where the too th in question may be a maxil­lary central incisor, a seco nd premo lar or an yother too th. A generous flap design helps todi stan ce the edges an d u nd erside of the flapfrom the field of o perati on is im po rtant if con­laminat ion with blood is to be avo ided duringbonding.

We may sum marize the ad vantages andd isad vantages of complete flap closure w iththe alte rna tive techn ique in which exposure isma in ta ined by red uci ng the s ize of the flapand pa ckin g the wound .

Prill/aryfull fla p clos ure

Advantage s:• rapid hea ling• less d iscomfort• good post-operative haemostasis• less imp ed iment to fun ct ion• conserva tive bone removal• immed iate tractio n possible• reli ability of bond ing.

Disad va ntages:• p resence of o rthodont ist requ ired• bon d fail u re d icta tes re-exposu re• di fficu lty in ga ining d ry field .

SURGICAL EXPOSURE OF IMPACTED TEETH

SecoJldary doeure toitli }lllck

Ad vantag es:• o rthod ontist's presence unn~cessary

• bond failure - needs no surgery.

Disad vantages:• more d iscomfort• wider bone exposure• man)' visits to change pa cks• greater risk of infect ion• bad tast e and smell in mouth• bond ing reliab ility poo rer• de laved initi ati on of trac tion• poorer periodontal condi tion .

Once the bo ny sur face ha s been bared andthe loca tion of the buried too th id en tified, thethin overlying bone may be lifted off ve ryea sily. The su rgeon will generally use a sharpchisel with light hand p ressu re to cut openthe bony cryp t and to remove the su pe rficialpa rt of its wall. The bo ne is ofte n pa per thin,and ca n even be cut w ith a sha rp scalpe l.Immediately be neath the bo ne, the dental fol­licle will be seen to glis ten in the beam of theopera ting lamp. A window shoul d be cu t inthe follicle to fu lly match the exten t of theve ry minimal bo ny opening tha t ha s alreadybeen ach ieved, in order to see the ori en tati onof the tooth as it lies in its cry pt.

As we shall describe in later chapters in thisbook, it is important to place the attachmentas close as po ssible to the midbuccal positionof the crown of the tooth, in order thattraction will ten d to improve any ex istingrotation, thereby reducing the amount ofmecha no therapy to which the tooth will needto be subjected . For this reason. where arotated tooth is exposed, the bony openingshould be exten ded around the crown of thetoo th, toward s the midbucca l area of thecrown, provided that this may be done wit hease and w ith the inflict ion of relati vely littlefurther surgical d amage. In th is instance, flaprep lacement ma y be completed and the pig­ta il ligatur e, tied into the newly placed attach­ment, drawn in the d irection of the p roposedtarget s ite in the d enta l arch .

Du ring expos ure of the crown of a too th,instrumentation of the enamel surface is no tdetri mental to the eru ption process or to

the quality o f the treated result. However,exposure and instrumen tation o f the roo t su r­face are potentially da magi ng . Exposing theroo t su rface p re-supposes that the ccmcn to­ena mel junction, the na tural attachment of thetooth, will ha ve been ruptured, and renewedattach ment w ill probab ly only be es tablishedmore apically. Addi tionally, pe riodonta lfib res are severed. cementu m exposed . andsubjected to drying (sucti on and air syringe)and con tact with fore ign substances (etcha ntand bonding materials). Th is can lead to thelater initia tion of a reso rptio n p rocess on theroot surface, and to anky losis and failure oferuption in ex treme ins tances. More com mo nsequelae include serious ly reduced bonesu pport, long clinical cro.....ns, poor gingivalatt achment and con tou r, chronic gingiva l mar­gin inflammation and pocketing . In sho rt, thequality of the periodon tal res ult will be com­promised.

COOPERATION BETWEEN SURGEONAND ORTHODONTIST

From th is d iscussion, the rea der shou ld havecome to realize the na rrow lim itations of thesurgeon's ability to ma terially ass ist thesecases and h ave come to appreciate that theinclusion of orthod ontic procedures offersmost cases a bett er cha nce of success. Today,orthodontists have come to play a moredominant role in the initi al stages of the treat­ment of impacted teeth, by providing the trac­tion that is necessary to encourage thiseru pt ion and, in ma ny cases, to do so success­fully in teeth tha t were previously felt to havea poor prognos is for er u ption.

The stat us of an impacted tooth tod ay islargely d ependent on the ab ility an d. the inge­nui ty of the orthodon tist to apply light trac­tion in an appropriate d irection and withefficient means, once the tooth has been madeaccessib le by the ora l su rgeon. If or thod ontictraction is available to the pat ient, there is lit­tle merit in the su rgeon offeri ng an y of theother p roced u res listed ab ove, since there isno av ail able evid en ce to suggest that theseproced u res may enha nce the oppo rtu nity for

35

orthodontic resolution wi thout causing con­current hann.

We may therefore conclude that, withrespect to the treatment of impacted teeth, theaims of the oral surgeon should be limited to:

(a) the pro vision of access to the buriedtooth;

(b) the clearing of an y obs truction in thetooth's eruptive path , such as supernu­merary teeth, odontomas or thickenedover lying mucosa ;

(c) taking an active part with the orthodon­tist in bonding an attachment to theexposed teeth at surgery, by maintaininghacmostasls, which is so critica l in ensur­ing success.

The single most important aim of the surgi ­cal ep isode is to provide the means by whichforce may be applied to the tooth in question,thro ugh several subseque nt visits, over alongish time span and in as simple a manneras possible. For this to happen. an attachmenthas to be securely bonded and a firm ligaturedrawn to the exterior, to which steel or elasticligatures or an aux iliary spring may be tied . Asharing of the responsibility for the resolutionof the impaction should be un dertaken byoral surgeon and orthodontist, with one spe­cialist complementing the othe r in applyingtheir very special skills to the resolution of theimmediate task. Together, they possess all thetools that are needed to complete the job.Thei r combined efforts should be geared toachieving this.

Bonding an attachme nt to the too th at alater visit, a few weeks after surgery has beenperformed, has the adva ntage of not requlr­ing the presence of the orthodo ntist at thesurgeon's cheirsidc . However, as will beexplained in greater deta il in later cha pters,by doing this, the surgeon mus t exp ose thetooth much more widely, place surgical packsand a im for healing 'by secondary intention'onl y. Additionally, the reliability of the bond­ing at this later date is much poorer thanwhen performed at the time of surgery(Becker et al, 1996).

For the pu rpose of bonding orthodonticbrackets to erupted teeth in day-to-day prac­tice, the teeth are first cleaned using a rubber

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

cup and pumice. The aim of this proced ure isto remove extraneous materials, which in­clud e soft plaque, d ried saliva, organi c andchemical staining an d deposits that adh ere oradsorb to the ena mel prisms and tha t mayprevent penetration of the acid. Once theseare removed , the enamel surface becomesvulnerable to the orthophosphoric acid et­chant, which is the key to successfu l adhesionof the attachment

By contrast, newly exposed impacted teethare com pletely free of these extraneous ma te­rials. Their only covering is Nasmyth's mem­brane, which is made up of the enamel cuticleand the reduced enamel epithelium, and isabout 1 JIm thick. This ap pears to presen t nobarrier wha tsoever to the etching effectachieved by the app lication of orthophos­phoric acid (Becker et al, 1996). Accordingly,there is no ad vant age to be gained by pumic­ing these teeth as part of the bonding proce­dure . Rathe r, the reverse is the case. Topermit the introd uction of a handpiece andrubber cup or a sma ll electric toot hbrush orhand bru sh, exposure has to be considerablybroade r for prophylaxis to be effective. It isd ifficult to control these implements du ringthe bru shing exercise, and, as a din..ret conse­quence, the bru sh or cup traumatizes theexposed. bone an d soft tissues. This generatesrenewed bleeding, wh ile giv ing rise to a dis­pe rsal of the pumice over the immed iate sur­gical field .

THE TEAM APPROACH TOATIACHMENT BONDING

This episode primar ily represents an adjun c­tive surgical procedure, whose <l im is toprovide a site for the application of an or tho­do ntic force-delivery system. As such, itshou ld be carried out on the surgeon's ter ri­tory and no t in the orthodontic clinic. Theorthodontic treatmen t will have been initiatedand orthodontic appliances will, most often,be in place before the surgical exposure isattempted. Orthodontic procedures that needto be carried out during the su rgical ep isodeare few and relatively simple, and can all be

SURGICAL EXPOSURE OFIMPACTED TEETH

perform ed in the ora l surgeon' s operatory.However, the o rthodon tist needs to p repare asma ll tray o f ins tru ments an d materia ls tha tare not norm ally availab le in the operatingroom, together with a prepared auxiliarysp ring, which may ha ve been fabricated at ap revi ou s visit for the p ur pose of applying ad irect iona l fo rce to the impacted tooth, suchas a 'ballts ta' (Jacoby, 1979), a flexible pa latalarch (Becke r and Zilbc rman, 1975, 1978) or alabial spring auxilia ry (Korn ha user et al,1995) (see Chapter 6). The ins tru ment tra yshould contain the following items:

Instruments

• a fine plie r (e.g. a Begg wire-bending plier)• a fine 'wire cutter• a reverse-action bracket- holdi ng tweezer

that is closed when not held and releaseswhen its handles are lightly squeezed

• a ligature d irect or• a mosquito or Matthieu force ps• a fine sca ler

Materials

• etchi ng gel• com pos ite bond ing material, pre ferably in

the form of a no-mix paste and catalyst,wh ich is probably the most ma nageablety pe of bond ing method that may be usedin these special circumstances

• ap plicators (wood sticks, fine brushes etc.)

Attachments

• eyel ets we lde d to band material, backedwi th s tain less steel mesh; these should becu t and tr immed into pa tches of var ioussizes, but no t Luger than the base of asmall bracket

• cut lengths of de ad sof t stainless steel liga ­tu re wire of ga uge 0.011".

• elastic thread, elast ic ligatures of varioussizes o r clast ic chain

The surgeon reflects a mucope riosteal flapover the impacted tooth and removes theinterven ing bone, which is usually very thinand easy to peel with a scalpel blad e. Theden tal follicle is removed from the target area

immediately ove rlying the crown, and theresultant exposure is not widened mo re thanis necessary to sa tisfy two basic req u iremen ts(Figs 3.8a,b):

(a) to p rovide enough enamel surface toaccept a small atta chm ent ;

(b ) to d o so in an a rea wide enough for ade­qu ate haemosta sls to allow the bond ingp rocedure to take place without fear ofcontamina tion.

The surgeon then moves to the ot her side ofthe operating couch, in orde r to take over theentire responsibility for maintaining theenamel su rface free of blood and sa livathroughout the cri tical bonding phase ­which is, after all, the point of the en tire exer­cise!

Under the cond itions of exposed and ooz­ing soft tissue and bone surfaces, th e su rgeonwill generally need to use a regul ar suctiontip and a second very fine tip in th e form of acanula No. 14 or 16, in ord er to maintain abloodless field of opera tion for the bondingp rocedure. Occasionally, a pe rsis ten t bleedingpoint from the bone surface may requireei the r pressure from a blunt ins tru ment or theapp lication of bone wax to occlude the tinyvessel. Soft tissue bleed ing ma y be controlledw ith an electrocau tery, a hot bu rn isher or,occasionally, ligation of the vessel. Bleedi ngin the folli cu la r space is bes t a rrested w ith theuse of light p ressure from a strip o f ga uze,which may be left in place u nt il su turing isbegun.

The orthodontist proceeds di rectly to rins­ing the tooth surface with sterile saline from alarge syringe, through a wide-bore needle, tod isperse any blood from the tooth su rface,and the saline is eva cuated thro ugh the broadsuction tip, opera ted by the su rgeon. The finesuction tip is then subs titu ted and is made tohover ove r the entire exposed crown, close tothe tooth surface, with the aim of d rawing airover the clean ename l. Th is achieves effectived rying .

Liqu id etchants should not be used in theexposed surg ical field (Kokich and Mathews,1983), since it is d ifficult to p reven t theirsp read to the exposed so ft tissues and bonesurfaces an d, perhaps mo re im po rtantly, to

38 THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(d '

Figure 3.8

(ill The crown of an imp.Ktt",) canine is ('X~. usi ng ... wide flap, but w ith removal of minimal bone. The un('xp<N.odcrown tip lil~ bdwl,.'n the TOols Ilf the central incisors, having traversed the midli ne sut ure. (bl An attachment isbond•...J . whil., h,WlTlosldSi" is maintained by the surgeon. Ie) The flap has been d ivided 10 accommod.ue lhl' !ig.ll llrepigt .li l in it" desin-d position, before bt.>ing fully replaced and sutured. (d ) The labial spring auxiliary I"up. St.... n in itsp.l"",i\'<.· p..."ition in k ). h.1S been turned inwards towards the palate and secured 10 the stain les s ste....·l li);,l lur ...p ig t.liL

the area of the cemcnto-enamel junction andthe too th attach me nt Mea. Etchn nt is bestapplied as a gel on the end of a fine woodentoo th pic k applicator (non-medicated ), left inp lace for 30 seconds and then d raw n off bythe surgeon, through the fine suction tip,before the su rface is rin sed again with salineto remove the last traces of the acid.

Continua tion o f the usc o f the fine tip willd raw air over the su rface of the crown of thetoo th until dessicat ion is achieved, and thetypical whi te matt appearance of the etc hed

surface will then qu ickly ap pear. Th e surfaceis now ready for bonding.

Many practitioners may be concern edab out the adequacy of the dessica tion , andma y also prefer to be sure th ..at no sa lt crystalsrema in from the d ried sa line . Experienceshows such worries to be g rou nd less.Never the less, to alla y the m, a final rinse withatomized water from the triple syringe maybe followed by a fine compressed air s treamto achieve the ap pro priate degree of drynessof the enamel surface. For thi s to be success-

SURGICAL EXPOSURE OF IMPACTED TEETH

ful, the compressed air stream must be verygentle, to avoid splashing up blood from thesurgical area , wh ich will contaminate theena mel and cause bond failu re.

The prepared eyelet attachment has a pli­able base. An attachment of appropriate sizesho uld be se lected and adapted between theplier and the gloved hand of the or thodontist,to fi t the target bonding site. A cut length of0.011~. (0.275 nun) dead soft stainless steelligatu re wire is threaded thro ugh the eye let,and, wit h the use of the mosquito or Matthieuforceps, is twisted into a medium tight andfirm pigtail, which should swing freely in theeye let.

Strictly, any type of bondi ng agen t may beused, includ ing ligh t activated and chemicallyactivated systems. Our ow n preference is fora chemically activa ted 'no-mix' system, suchas Rely-a-Bond" (Reliance Orthodo nticProd ucts, Inc, Itasca, IL) or Right-On " (TPLaboratories, Inc, Laporte, IN). In this system,the attachment is seized in the reverse-actionbond ing tweezer, and its mesh base is pa in tedwith the catalys t liquid . A sma ll quan tity ofbonding paste is placed on the attachment ,wh ich is delivered to the ope rating area. Theetched ena mel is checked for dryness onceagain, and then painted with the liqu id cata­lys t. The attachment is pressed firmly intoplace on the crown of the tooth, until pasteoozes from underneath the mesh base. Evenwithout wait ing for initial sett ing, the viscos­ity of the paste will ho ld the attachment inplace without the need for any support, an dcareful fine-tip suction in the surroundingare a is probably all tha t is needed to gua ran­tee bond ing success.

Many operato rs prefer to usc the mosqu itoor Matth ieu forceps to carry the att achm ent toits place and to hold it there unt il setting hasoccurred. Unfortuna tely, the freeing of theattachment from the forceps is achiev ed bychanging the hand grip and unlocking theratchet tha t ho lds the handles closed . Thesemanoeuvres prod uce cons iderable jolt ing andjarring of the attachme nt, which may seri ­ously undermine the streng th of the freshlycrystallized bond.

Accordingly, it is better to use the reverse­action bond ing tweezer, wh ich may be much

mo re gently disengaged immediately theatt achm ent is in place and , preferably, beforethe initial se t has occu rred . If continuo uspressure is desired during the setting period,the ligatu re di rector may be substitu ted forthe tweezer an d placed with its notchengaged ast ride the eyelet loop and pressingagainst it. To free the ligatu re d irector, oncese tting is complete, it is merely wit hd rawn inthe direction of its long axis, without generat­ing any und ue lateral jarring. A sho rt timelapse of a few minutes should be allowedbe fore the new ly bonded attachment is testedfor strengt h, and this should be done befo rethe flap is resutured.

The replacement of the flap will h ide theimpacted tooth from sight once aga in, an d itwill become evident in later stages that it ispruden t to photog raph the tooth and itsattachment befo re closure is performe d (Fig.3.8). By photographically recording its posi­tion, subsequent decisions related to directionof orthod ontic traction may be more reliablymade.

As part of the or iginal orthodontic treat­ment plan, an accurate radiographic assess­ment of the position of the impacted toothwill have been ma de and an approach to itsorthodontic reso lution formul ated . With theimpacted too th now in full view, the ortho­dontist mu st confirm how it is to be moved toits place. If this is to be per formed in a di rectline to the prepared place in the dental a rchthen the pigtail ligature will be swivelled onthe eyelet until it po ints in that d irection. Thesurgeon will then su ture the flap back ove rthe wire, leaving its end freely protr ud ingthrough the cut and sutured edges.

As we shall d iscuss with regard to apalatally impacted max illary canin e (Chapter6), some times the direction of the tractioncannot be pointed straight to the labial arch­wire, becau se of the proximity of the roots ofadjacent teeth. In this case, the wire may ini­tially need to be drawn vertically do wn ­wards, tow ards the tongue. To achieve this,the pigtail cannot be drawn through thesutu red edges of the flap, but rather must betaken through the middle of the pa lata l area.T~is means tha t the reflected flap must bedivided into two halves, one on eithe r side of

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH40 - - - - - - --- - ----- -=---=---=------'---the pigt ail, to accomodate th is (Fig. 3.8e). Abette r alte rnat ive is to pass the pigtail througha small pinhole in the palatal mucosa, prior torcapprox imation and sutu ring of the flap .When sutu ring is completed an d the palatalarea co mpletely closed off, the orth odontistshould shorten the pigtail and tu m it up intoa hook o r circle, to be attached to an act ivepalatal arch, ballista or labial spring auxiliary(F;g.3.8d ).

The application o f traction sho uld be imme­d iate , regardl ess of which method is used. Itwill be appreciated that later manipulation ofthe ligature pigtail as it passes through thesoft tissues is very unp leasan t and evenpainful for the patient. While subseq uentmanipulation may only be necessary for twoor three add itional adjustment visi ts beforethe tooth is erupted and the p igtail free of thesoft tissue, the re is m uch to be said for thefirst of these being fully exploited w ith theapplication of appropriate traction while alocal anaesthetic is ope rational.

The reliability of the bond ing proced ureunder the circu mstances described here hasbeen shown to be extremely high (Becker etal.-19% ). In the past. however, bondi ng in thepresence of an open and bleed ing wound.involving bot h soft and hard tissues, wa s con­sidered stro ngly con traind icated . since it wasthou gh t to be inco ns istent with the attain­ment of a d ry and uncontam ina ted field . Th isatt itude, on the pa rt o f the orthodontist. wasp robab ly nurtu red more ou t of a ret icence tobe present at the surgical episode th an ou t ofany experience of a h igh incidence of failurein attach ment bond ing at that time.

It is important to em phasize the need toproperl y adapt the base of the attachment tothe shape of the recipient su rface of the cro wnof the tooth . Th us the use of standa rd brack­ets with 'anatom ical' bases, as supplied by thema nufac turer, we re shown by Becker et a l(1996) to fare considerably better in the mid­buccal position o f the impacted tooth (80.6%)tha n on any other su rface, pa rticu larly thepa lata l su rface, where the chances of its su r­viva l are 58.3°,1" - a failu re rate of almost 1 in2! Better s till, and at a 96.7% level o f reliab il­ity, a small attachment (such as an eyelet) ona pliab le base, prope rly and ind ivid ua lly

adap ted to the form of the recipient site, willallow the or thod ont ist to wor k w ith the great­est deg ree of confide nce.

It w ill be apprecia ted that the presence ofthe o rthodontist at the su rgical interventi onhas much to co mmend it. In the first p lace,the orthodontist is able to see the exact pos i­tion of the crown, the d irection o f the longaxis and the ded uced loca tion of the rootapex. The height o f the tooth and its relati onto adjace nt roo ts may all be noted, and theorthodontis t may plan the strategy of its reso­lu tion by d irect visio n. The orthodontist willbe in a position to deci de exactly where he orshe would like to see the attachment placedfrom the mechanotherapeutic point of view,and will bond it there.

It is not fair to expect the ora l su rgeon to beaware of how different atta chment positionsmay affect the orthodontic or periodonticp rognosis, and neither should it be expec tedof him or her to be sufficient ly experiencedwi th the bonding technique to do this. Form ost or al su rgeons, bond ing is no t a proce­dure that they norma lly carry out. The pres­ence of the or thod ontist allows for bonding tobe performed efficien tly, with the su rgeonand nu rse maintaining haemostasis and thenecessary d ry field .

REFERENCES

Altuna G, Walker DA, Freeman E (1995)Rapid ortho pedic lengthen ing of themand ible in pr imates by sagittal sp litosteo tomy and dis traction osteogenesis : ap ilot stud y. int ] Adult Grtnod Or tlwgnath Surg10: 59-64 .

And reasen 10, And reasen FM (1994) Textbookand Color Atlas of Traumatic Injuries to theTeeth. Munksgaard , Copenhagen.

Becker A, Shochat S (1982) Submergence of ade ciduous tooth, its ramificat ions on the de n­titian an d trea tmen t of the res ulting malocclu ­sion. Am Jart/lOll 81: 24()-4.

Becker A, Zilberman Y (1975) A combinedfixed -removable approach to the treatment o f

SURGICAL EXPOSURE OF IMPACTED TEETH

impacted maxillary canines. / Clin Orthoaont9, 162- 9.

Becker A. Zilberman Y (1978) The palatallyimpacted can ine: a new approach to its treat­ment. Am / Orthod 74: 422- 9.

Becker A, Kohavi 0 , Zilberman Y (1983)Periodonta l statu s following the align ment o fpalatally im pacted ca nine teeth . Am / OrtJlOd84, 332-6.

Becker A, Shpa ck N, Shteyer A (1996)Atta chm en t bonding to im pacted teeth at thetime o f su rgical exposure. Eur / Orthod 18:457-64.

Blackwo od HJJ (1958) Reso rpti on of enameland d en tine in the uneru p ted tooth. Oral SurgOral Mel! o-« Poth 11: 79-85.

Boyd R (1982) Clinical assessment of inju riesin orthod ontic movemen t of impacted teeth . I.Methods of atta chment. Am / Orttiod 82:478-86.

Boyd R (1984) Clinical assessment of injuriesin orthodon tic movemen t of impacted tee th .II . Surgical recommendations. Am / OrlhOO 86:407-18.

Crescini A, Clauser C Giorgetti R et al (1995)Tunnel traction of intraosseous impactedmaxillary canines: a th ree-year pe riodontalfollow-u p. Am / Orinod Dentofac a rt/lOp 105:464-76.

Oi Biase DO (1971) The effects of vari ations intoo th mo rpho logy and position on eruption.Dent Pract Dellt Rec 22: 95-108.

Heaney TG, Atherton JD (1976) Peri od ontalproblems associated with the surg ical expo­sure of unerupted teeth . Br / OrtllOdol1 t 3:79-85.

Iliza rov G, Devya tov A, Kamcr ln V (1980)Plas tic reconstruction of longitu d inal bonedefects by means of compress ion and subse­quent d is traction . Acta Chir Plast 22: 32-46.

Jacoby H (1979) The ballista spring syste m forimpacted teeth . Am / Orthod 75: 143-51.

Kohavi D, Becker A, Zilberma n Y (1984a)Surgical ex posure, orthod on tic movementand final toot h position as factors in peri­odontal breakd own of treated palatallyimpacted can ines. Am / Orthod 85: 72-7.

Kohavi D, Zilberman Y, Becker A (1984b)Periodontal status following the alignment ofbuccall y ectopic maxillary can ine teeth . Am /Orthod 85: 78-82.

Kokich VG, Mat hews DP (1983) Surgical andorthodont ic management of impacted tee th.Dent cu« N Am 37: 181-204.

Korn hauser S, Abed Y, Haran D, Becker A(1996) The resolutio n of palatally-impactedcan ines using palatal-occlusal for ce from abuccal auxilliary . Am / Crthod Dt'lltof ac Orthop110: 528-34.

McBride LJ (1979) Tract ion - a su rg ical/orthodontic p roced ure. A m / Ortltod 76:287-99.

McDonald F, Yap WL (1986) The surgicalexposure and application of direc t traction ofunerupted teeth . Am / Ort1lod 89: 331-40.

Odenrick L, Modeer T (1978) Periodontal sta­tus following su rgical-orthodontic alignmentof impacted tee th . Acta Udontol Scand 36:233-6.

Vanarsdall RL, Com H (1977) Soft-tissuemanagemen t of labially positioned uneru p tedtee th . Am / Orthod 72: 53-64.

Vermette ME, Koki ch VG, Ken nedy DB (1995)Uncovering labia lly impacted tee th : apicallypositi oned flap and closed -eruption tech­niqu e. Angle Ormod 65: 23-32.

Wisth PJ, Nord ervall K. Boe O E (1 976)Periodontal status of orthodonttcally treatedimpacted max illary canines . A I1Kle Grtliod 46:53-7.

Wong-Lee TK, Wong FCK (1985) Maintain ingan idea l too th-gingiva relationship whenexposing and align ing an impacted tooth . Br /Or/hod 12: 189-92.

41

4 TREATMENT STRATEGY

CONTENTS • Orth odon tic trea tment duration • The anchor unit • AUachments• Elas tic t ies and mod ules versus auxiliary springs • Magnets

ORTHODONTIC TREATMENTDURATION

The opening of adequate space in the archmay ini tiate movemen t in an unimped edimpacted tooth, which may slart moving inthe appro pri ate d irection, so metimes quitequickly. By the time the space is of sui tablesize and the a rran gem ents for surgery havebeen made, a new periapical radiograph mayshow much positive change in its positionand lead the clinician to believe that sponta­neous eruption will rende r the surgeryunnecessary. If the eruption is likely to occurimminently, or at IC<Js t with in a reasonableper iod of tim e, then there is meri t in waitingfor this to occur .

If, on the other hand. er up tion will takemany months then the orthodontist mustweigh the benefits of avoid ing surgeryagainst the d rawbacks involved in leavingorthodontic ap plian ces in place for all thistime or in removing them before all the teethare in their appropria te places. Orthodon ticappliances raise the level of vulnerab ility ofthe tee th to cari es and of the periodontium toinflam mation - the longer they are in p lace,the greater the risk. Remov ing the appliances

before time runs the differen t risk of havingto later repl ace them to correct a ma lpositionof the new ly erupted and ers twhile im pactedtoo th . In order to so lve this d ilemm a, theclinician may elect to .ad vise surgical expo­sure and orthodon tic traction. thereby expe­diting the eru ption of the tooth an d com ­pleting the treatment in a very much shortertime frame.

When orthodontic treatment ha s providedspace, and surgery is undertaken to remove aphysical obstacle, a similar d ilemma mayoccur. In the absence of the obstacle, theimpaction is po ten tially resolvable, unaidedby further treatmen t. However, the surgicalinterven tion involved in removing the obsta­cle offers the opportunity of access to theun eru p ted tooth . Subsequ ent healing of thewound will deny tha t access, and, in theevent that eruption doc s not take place, a sec­ond surgica l intervention in the same areawill be necessa ry and mu ch time will ha vebeen wasted confirming that spon taneouseruption will not occur. Clearly, then, thetime factor must not be ignored . Orthodonticappliances are in p lace, and perha ps the spacein the arch is unsigh tly . Without question,orthod ontically aided erupt ion will speed up

44

the resolution enormously, and. this being so,the patient' s best interests arc to be served byincluding this op tion among the factors to beconsidered at the p lannin g stage.

When the existence of an impaction is onlya sma ll pa rt of an overall complex malocclu­sion , the tim e factor becomes more critical. Itis quite conceivable and reasonable to esti­ma te that a given overall p roblem, alone, mayrequire a z-year treatment period. The com­plete alignme nt of an awkwardly placedim pacted too th may add a further year ormorc to this period. To permit the luxury of a'wait-and -sec' perio d is to add this time to analready extended a-yea r period d uring whichappliances arc worn . Wh ile the o rthodon tistmay we ll be rewarded by a much improvedpos ition of the impacted tooth, the state ofhealth of the teeth and pe riodontium m aydepr ive the achievement o f all meaningfu lcontent.

THE ANCHOR UNIT

At this jun ctu re, it is not the intention to gointo the details o f appliance therapy. This willcome later, as the different groups ofImpacted teeth tha t are seen in practice aredea lt with. However, so me general principlesare appropriately given here.

For most malocclusions, quality treatmentis best pro vided by the usc o f one or other ofthe recognized fixed appliance treatmenttechn iques. If the den ial arc hes are cor rectlyrelat ed and adequa te space is present then theteeth ar e initi al lv ' levelled' to a labia l arch­wire of standard ized ar chform and a givencoeff icien t of ela sti city . Later, heavier rou ndor rectangular archwires are substituted toperfor m roo t movemen ts that will pave theway to achieving an optima l result. Incor­rectly rela ted dental ar ches will benefit fromthe use of othe r appliances, such as head­gears, functional appliances and intermaxil­lary elastics, p rior to or in ad dition to thefixed applia nces, while space may be pro­vided by the extraction o f teet h or by expand­ing the arches mesic-distally or laterally.

When deal ing with a ma locclusion tha t

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

incorpora tes an impacted tooth, mod ificationsmust be made to thi s procedure. Unlike otherteeth in the mouth, the im pac ted tooth maybe severely d isp laced from its norm al posi­tion in all three planes of space, an d muchanchorage will be expended in bringing itinto alignmen t. Accordingly, it is necessaryto develop a rig id ancho r base against whichto pit the forces required to reduce theim paction.

At the age at which an impacted maxillarycanine is treated, the fu ll permanent dentition(wit h the exception of thir d molars ) is almostinva riab ly p resent. Acco rd ingl y, a fully multi­bra cketed appliance should normally beplaced and the ent ire de nt ition treated,through the stages of levelling and the op en­ing of adequate space in the arch for theimpacted tooth . A heavy and more rigid arch­wire is then placed in to the bra ckets on all theteeth o f the fully aligned and comple te dentalarch. The aim of th is is to provide a solidan chorage base (Kokich and Mathews, 1993)thai will not allow d is tortion of the archw ireto occur as a result of the forces tha t willeventually be applied to the im pacted toothafte r its exposu re. The effect on the an chorunit of forces designed to resolve a grosslydi sp laced canine should not be underesti­ma ted , parti cu larly if they are applied for anex tended peri od .

By contrast, at the time when an impactedcentral inciso r requires treatment, only firstperm anent molars and th ree perm anentinciso r tee th are p resent. Accord ingly, alter­native means of making the appliance systemrigid must be employed before ligh t forcesmay be applied to the impacted tooth, inorder no t to compromise the remaind er of thedentition.

ATIACHMENTS

To be in the position of being able to influencethe furore development of an im pacted tooth,it is necessary to place some form of attach­men t on the tooth. These attachments ha vechanged over the years , reflecting the ad­vances made in the field of den tal materials.

TREATMENT STRATEGY 45

Figure a.I

L.1S!'><) wire en circling th e ru-ck of an im pacted can ine.

Lasso wires

In the years prior to the mid-1960s, a lassowire (Fig. ·tt) tw isted lightly aro und the neckof the canine had been employed widely, andwas used in our earli er cases in the initialstages. It will be readily appreciated that theshape of the crown of a tooth is such that itsnarrowest d iame ter is at the CEl, which iswhere the lasso wire will inevitably sett le.

Figu re ~.2

Threaded pins set into prepared holes. drilled and tappedinto the enamel and dentine of the surgically exposedcanines.

This will result in irritation of the gingiva andprevent reatt achment of the healing tissues inthis vital area. It has also been reported thatexternal resorption an d ankylosis have beenproduced in the area of the CEl followin gemployment of this method (Shapira andKuftinec, 1981). Given the excellent alterna­tives that are available todav, the lasso wire isobsole te. '

Threaded pins

Severa l systems of threaded pins (Fig. 4.2)have been avai lable for many yea rs. Theirspecific purpose is to prov ide retent ion for anama lgam or composite core, to allow the pro­vision of a cast crown in a severely brokendown tooth. These threaded pins may also beused to provide the attachment for animpacted too th. This is a method that wasused in the past (Kettle, 1958; Becker andZilberman, 1978), but has been totally super­seded. Its d isadvan tages include the fact thatit is dentally invasive, necessitating a sub­sequent restora tion. Given the dif ficultiesof access to many im pacted teeth and thedesirability of limiting su rgical exposure asmuch as possible. the orientation of the long

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH46 ------------"-'-----'--'-'--------=-----------axis of the tooth may be d ifficult to deter­mine, and the drilled hole may inad vertentlyen ter the pulp - un erup ted teeth often havelarge pulp chambers! Neverth eless, themethod is st ill in use in some quarte rs(Kokich an d Mathews, 1993).

Orthodontic bands

Preformed or thodontic bands largely replacedthe lasso wi re, and clinical experience wi ththem showed them to be considerably morecompatible with ensuring the health of theperiodontal tissues . As with the lasso wire,however, the use o f a ba nd dictated the verywide surgical clearance of tissue on all sidesof the tooth (see Fig. 6.32c), in order to ade­quately control haemorrhage aroun d thecrown and to avoid contamination from ooz­ing blood inside the cement-filled band at thetime of placement.

Since the introd uction of enamel bonding,all of the above- mentioned ea rlier methodshave become obsolete . The em ployment ofthe ad d-e tch com posite bonding techniq ue tothe crown of a too th has m uch merit (Gensio rand Strauss, 1974; Nielsen et al. 1975), notablyin terms of the simplicity and reliability of thebond. Its most important advantage is that itrequires rela tively little exposed surface ofenamel for it to be successful - a fact that ma ycontribute greatly to the subsequent peri­odontal health of the treated resu lt . It isp resent ly witho ut doubt the meth od of cho icefrom almost every poin t of view, and itshould replace oth er methods in virtually alldrcu rnstances.

Standard orthodontic brackets

As far as the actual choice of ty pe of attach­ment to be placed on impacted teeth is con­cerned, there ar e several sa lien t po ints toconside r regarding the Impac ted too th whencompared with an erupted tooth tha t requ iresto be brought into its position in the dental

FiguO' 4.3

As the impacted tooth is about to eru pt, the high profileSiamese edg ewise bracket has fenestrated the swollengingival tissue.

arch. Edgewise, Begg and other orthodonticbrackets represent sophisticated designs ofattachment tha t enable the orthodon tist toperform any type of movemen t on a tooth inthe three planes of space. It is not possible,however, to ach ieve mo re than tipping, ex tru­sion and some rotation until the bracketreaches and fully engages the main archwire.In other words, its efficacy up to tha t point isno gre ater than that of a simple eye let (Beckeret al, 1996).

The base of a convention al b racket is wide,rigid and difficult to convert to the sha pe ofanother pa rt of the tooth 's sur face other thanthe mid-bu ccal, for which it has . beendesigned . Thus composite bond ing elsewhereon a tooth is very like ly to lead to failure (seeFig. 7.6) (Becker et al, 1996).

The standa rd ort hodon tic bra cket in anytechnique is relatively large, possesses a wide,high and sha rp profile, an d, even whenplaced in alternative pos itions on the too th,by force of circumstance at the time ofsurgery, it is inevit ably dee ply sited in thesurgical wound . The bracket ' s shear bu lkcreates irritation as the tooth is later d rawnthro ug h the soft tissues, particularly the

TREATMENT STRATEGY

mucosa (Fig. 4.3). A ligatu re wire or elasticth read tied to it must also originate deep inthe wound, and w ill be stretched across therep laced flap tissue towards the labial arch­wire. Th is increases the possibilit y of interfer­ence with the inves ting tissues, and leads toinflammation and to probable permanentperiod on tal dam age.

As the d isp laced tooth moves towards itsplace in the arch, exuberant gingival tissuebunches up in fron t of it , which will also leadto impingemen t by a conventional o rthodon­tic bra cket. The existe nce of the exuberan tgingiva l tiss ue in advance of the too th canoften cause 'p inching' between it an d theteeth in the arch immediately adjacent to it.This is less likely to occu r if a deli beratelygenerous space is p rovided in the arch for thetooth, and this precaution may avoid unnec­essary peri od ontal damage. Because of theclose proxim ity of an impacted tooth to theroots of adjacent tee th, it is often impossibleto bond a conventional bracket in its p rope rp lace on the tooth. Accordi ngly, the bracketma y have to be sited on the palatal su rface ofthe too th, where its prefor med base is con­toured very d ifferen tly from the shape of therecipient (pa latal) a rea o f the tooth, compro­mising its retentive properties .

Figu re 4.4

Eyelets welded to a pliable band material base, backed bysteel mesh.

A simp le eyelet

An eyelet, we lded to band ma terial w ith amesh- backing (Fig. 4.4), is soft an d easy tocontou r, making its ad aptation to the bondi ngsu rface mo re accurate, which ma kes for supe­rior reten tive properties. Its relatively smallsize and lo w profile makes the midbuccalpos ition of severa l of the more awkwa rdlyplaced teeth cons iderably more access iblewhen compared with the p lacing of a conven­tional bra cket. Its modest. low -profile, d imen­sions are also less irritating to the su rround ingtissues.

For these reaso ns, a small eyelet is recom ­mended as the initial attachment, pl aced atthe time of su rgery and removed only whenthe tooth has progressed to the point where itis in close proximity to the archwirc. At tha ttime, it should be substi tut ed by the sametype of sophistica ted bracket tha t is beingused on the other teeth thereby perm ittingthe in itiation of the more intricate rootmanipulations of the tooth (ro tat ing. uprigh t­ing and torqueing).

We ha ve seen in Chapter 3 that there areimportan t pe riodontal ad vantages to begained by full closure of the su rgica l flap atthe end of the visit d uri ng which the surgicalexposure is pe rformed. Thus the impactedtooth is re-covered by the su rgical flap, an d islost from sight, unl ess the impacted too th isfairly superficially p laced . The on ly mannerin which contact may be maintained with it isthrough the agency of so me form of ligatu rewire, gold chain or clastic thread, which isattached to the eyelet before it is bonded tothe tooth .

Since elastic thread can only be tied once, itis not recommended for ,10 attachment that isnot clearly visible and accessible in themouth . Gold chai n would appear to beunnecessaril y sophisticated, although it isundoubtedl y su itable and sufficiently strongfor the purpose. The usc of a stainless s teelligature is fa r easie r from every point o f view,and is read ily at hand in the orthodontic andsurgical opera tory. Such a ligat ure is passedth rough the eyelet and twisted into a longbra id with artery fo rceps be fore bond ing isundertaken. The braided wire or p igtail

47

48

hangs loosely in the eye let until after bondingand resu turing have been completed, and itshou ld be of su fficient su bstance for it to berolled u p into a loo p tha t w ill not easily beunravelled by the application of the extrusiveforce. On the other hand, it must no t be soth ick that the effort that is needed to form theloop will seriously test the bond strength ofthe newly p laced attachment. In p ractice, theuse of a dead soft sta inless steel ligature wireof 0.011" or 0.012" ga uge is ge ne rally the mostsuitable.

It has been recommended that the p igtail bebraid ed in such a way that each two or thr eetu rns of the b raid arc followed by a smallloop, then two or thr ee more turns, anotherloop, and so on. In this wa y, the braidcomp rises a convenien t chain of loo ps, whichmay be shortened as necessary by cu tting offthe excess, while exploiti ng the loo p closest tothe ging iva l tissue (Ziegler, 1977). However,' roll ing up' the term ina l loop of a simplytwis ted stainless steel ligature as the toothp rog resses is simpler and 'user-friendly' .

ELASTIC TIES AND MODULES VERSUSAUXILIARY SPRINGS

At first glance, elastic ties of one sort oranother present the o rthodont ist wit h the mostconvenie nt mea ns of applying ligh t forces to atoo th, with a good range of action . Howe ver,their usc is usually far more d isap poin tingthan one may ini tially realize.

The manufacturer' s spool of elastic threadusually comes in the form o f fine hollow tub ­lug, wh ich is easier to tie than a solid thread.Most orthodontists tie the thread wi th a simpleknot that , when tying string, will not u nr avel.When tying elastomcnc thread, however, theknot tends to loosen , and much of the ori ginalforce of the tie will be lost in th is loose ning.When under tension , all the materials used tomake this elastic thread suffer a high deg ree offorce decay, which is very rapid and very sig­nificant. The force levels of chai ns of variouslengths are kno wn to decay to below th e forcerequired for tooth movement, in a period of

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

Figure 4.5

A direct ric us ing a vl'ry short length of elastic thread.

between 1 and 3 wee ks, dependi ng upon theamo unt of tension initially applied (Lu et al,1993; Storie et al, 1994).

Na turally, a shorter pi ece of stretched elas­tic (Fig. 4.5) will have a very sho rt range, andru ns the risk of applying an initia l excessiveamount of p ress ure if the tie is good - or noeffective pressure if the tie loosens. Theimmatu re pe riodontal membrane of therece ntly exposed tooth and the s trength of itsbonded attach me nt cou ld be severely tes ted .In the case of an unerupted too th close to theline of the arch, traction applied d irect ly fro mits attachme nt to the arch wire will ge nerallybe very inefficient, req ui ring freq uentchanges and prod ucing on ly a ve ry slowres ponse. For all pract ical pur poses, it isimpossible to measure or control such a force.

It is prude nt to use mo re distan t sites fromwhi ch to apply tra ction to the un eruptedtoo th, in order to includ e a greater leng th ofelastic thread to increase the range of the trac­tion force and thereby its effectiv eness inmov ing the tooth over a longer pe riod oftime. To do this, the elastic th read needs to bestretched to the target area on the archwtrc,th rou gh the agency of a loop bent in to thearchw ire a t that poi nt. The thread ma y thenbe tied back to the hook on the molar tu be ofthe same side, with care being taken to inserta stop in the erchwlre, mesial to the tube, in

TREATMENT STRATEGY

order to prevent mesial movement of themolar.

As a general ru le, elast ic thread sho uld beused as the go-between connect ing the non­elas tic s tL'C1 pig tail to a similarly non-elasticand heavy archwire . If a lighter archwire isused then the tie sho uld be made with a steelligatu re - the archw ire provid ing the clasticd isplacemen t. In this event, however, the d is­tortion of the a rchwire will bring about analteration in its shape in bot h the horizontaland vertical planes, to prod uce unwantedchange in the form of the dental arch and anuneven occlusal plane.

The use of bot h a flexible archwire and anelastic ligature (Shapira and Kuftinec, 1981) iscoun terproductive, since the elasticity of theone that exerts the stronger force will be effec­tively neutralized and will offer no physicaladvantage over a steel ligature, while the dis­placem ent of the weaker element will be theonly factor that is active in moving the teeth.

In general, orthodontis ts use elastic ligatureto move teeth by first elonga ting the materialand tying it between two dental elemen ts.Once tied, a na tural recoil is exerted alongits long axis, pulling the den tal elements

towa rds one another . The amoun t of elas ticityin this d irection is limited and , as pointed outabove, decays rapid ly. However, the laterald isplacement of an elo ngated elas tic threadprodu ces a po ten tia lly greater range of move­ment, with in suitable ort hodontic force levels,than does a longitudinal d isplaceme nt. Thisprinciple may be applied to moving teeth thatlie at a d istance from the main a rch mo re effi­ciently an d wit h controlled an d measurableforces (Fig. 4.6).

Given a litt le thought in the planning oftheir use, elastic ties, cha ins and modules areextremely helpfu l in many situ ations aris ingbecause of the presen ce of impacted teeth.However, properly designed springs, auxili­ary to a heavy base arch, are usually moreefficien t, since their abili ty to deliver a mea­sured and controlled force is good, the forcedecay is lower, the variety of metallic alloysavailable for spring fabrication is broad, an dtheir range of act ion may be very wide andtheir di rection accurate. These will be illus­trated in the discussion of cases as they per­tain to the individual gro ups of tee th in thesucceed ing chapters.

(h)

49

Figu re ~ . 6

(a) The 's lingshot' elastic. A pala tatly impacted canine has been erupted into the pala te [see Cha pte r 6). The clastic mod­ule, placed bet wee n the br<lckeb of the lateral incisor and the firs t premola r, is s tretched towards thl' canine and ned tothe buccal eyelet. The stee l tube on the archwirc maintains the space. (b ) The 's ltngshct' used on a bucc al canine.

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH50---- - - - ----- - - - - - - - - --

Figure 4.7

Tht.' 'backpac k' magnet. (Cour tesy of A Va rdfmon.]

MAGNETS

Ra re earth magnets we re developed 40 yearsago, bu t only more recently have they beendeveloped to the point where their red uctionin size, with the introd uction of lanthanidealloys, has provided the possibility of apply­ing suitable forces that ma y be exploited inthe present context. Vardimon et al (1987) andSandler et a1 (1989) ha ve recently presentedsucces sful clinical results of the treatment ofim pacted teeth in h umans.

The magnetic attracting force that existsbetwee n the two magnets is inversely propor­tional to the square of the distance betweenthem . This mea ns that a magnet s ited on theapplia nce must be placed dose to the magnetthat has been bon d ed to the d isp laced too th(Fig. 4.7) and that a grossly di splaced toothmay requ ire tha t the location o f the ap pliancema gnet be resited from time to time, in linewith the p rog ress of the too th. The forcesgenerated arc centripetall y orienta ted, and itis possible to design their application to movethe u nerup ted too th in all th ree planes ofspace from the very beginni ng and be fore thetoo th erupts (Vard imon et al , 1991).

The no tion that traction may be appliedwithout the need to tra il a wire through thesoft tissues of the palate, appeals to Vardimonand Sandler an d their co-workers. They spec-

u late that this may im prove the final pe n ­odon ta l con diton of the teeth, since 'erup tionsimulates a nonnal eruption process' . How­ever, given tha t

(a) the tooth must nevertheless initially beexposed. surgically,

(b) the magnet mus t be bonded to it,(c) the flap must be replaced and healing

must occu r, and(d) the tooth must then pass thr ough the tis­

sues wit h this rela tively la rge ' backpack',

th is claim may be d ifficu lt to jus tify in prac­tice .

The idea is in deed 'a ttractive' (San dler,1991), bu t it is no t a method that, at p resent,can u nequivocally rep lace the ma rc trad i­tional an d conven tion al methods de scribedabove (Ingervall, 1993; Gi anell y, 1993; Rygh,1993). The use of mag nets for impacted teethis in its early deve lopmental stages, and themethod s that have been d esc ribed appearra ther clu msy and inconven ient (Darendelilerand Friedli . 1994). Their grea test d isad van­tage is the corrosion (Vard im on, 1993) thatoccurs with their use in tissue and the, so far,u nsuccessful attempts at their hermetic isola­tion . The use of magnets in this context an dwith the present sta te of the art offers noadvantages over traditional methods, an dp rovides little more than curiosity va lue .

As these methods become mo re refined,particu larly w ith the ex pected futu re devel­opment of even smaller magnets of sufficientp ower, they may offer some rela tively minorad vantages over the es tablished method s.wh ich could make them more widelyaccepted for ro utine use in clinical p ractice.

REFERENCES

Becker A, Zilbcrman Y (1978) The pal atallyimpacted can ine: a new approach to its treat­ment. Am / OrtflOd 74: 422- 9.

Becker A. Shpack N, Shteyer A (1996)Attachment bonding to im pacted teeth at thetime of surgical exposure. ElIr / Or/hod 18:457-64.

TREATMENT STRATEGY

Darcndelic r MA, Fried li 1M (1994) Treatmentof an im pacted canine with ma gnets. I ClinGrthod 28: 639-43.

Cen sio r AM, Strauss RE (1974) The d irectbondi ng techniq ue applied to the ma nage­men t o f the maxillary impacted can ine. I AmDt'Ilt Assoc 89: 1332- 7.

Gianelly A (1993) The usc of magnets inorthodontic therapy: pan el d iscussion. Eur /OrthOl.i 15: 421-4.

Ingervall B (1993) The use of magnets ino rth od on tic the rapy : panel d iscu ssion . Eur TOrthod 15: 421-4.

Kettle MA (1958) Trea tme nt o f the uneruptedmax illary canine. fkn t Pract Dent Rec 8:245-55.

Kokich ve, Ma the ws DP (1993) Surgical andorth od ontic managemen t of impacted teeth .Dellt cu« N Am 37: 181- 214.

Lu TC, Wang WN, Tamg Ti t Chen JW (1993)Force d ecay o f elastome ric chains - a serials tudy. Part 2. Am I Ortbod Dentofac Ort/lOp1M: 373-7.

Nielsen LI, Prydso V, Winkler T (1975) Directbond ing on impacted teeth . Am I Orthod 68:666-70.

Rygh P (1993) The usc of magn ets in ortho­d on tic therapy: panel d iscussion . Eur I Orthod15: 421-4.

Sand ler JP (1991) An att racti ve so lut ion tou nerupted tee th . Am I Ortlwd Dentcfac Orthop100: 489- 93.

Sandler PJ, Meg hji S, Mu rray AM et al (1989)Magnets and orthodon tics. Br I Orthad 16:243-9.

Shapi ra Y, Kuftincc MM (1981) Trea tme nt ofimpacted cuspid s: the haza rd lasso. AngleOrthod 51: 203-7.

Sto rie OJ, Rege ruu ttcr . F, von Fra unhoferJA (1994) Characteristics of a fluoride­releasing elastomertc cha in. AI/gle Orthod 64:199-210.

Vardimon AD (1993) The use of magnets ino rth od ont ic therapy: panel discussion. Eur IOrthod 15: 421-4 .

Vardimon AD, Graber TM, Voss LR (1987)Hygien ic magnetic tech nique to align impactedteeth . Presen ted at the 87th Annua l Session ofthe American Association of O rthodontis ts,Montreal, 1987 (u npu blished).

Vard imon AD, Graber TM, Drescher 0 ,Bourau el C (199 1) Rare ea rth magnets andimpaction. Am I Orthod Dell fofae Ort/lop 100:494-512.

Ziegler TF (1977) A mod ified techniqu e forliga ting im pacted can ines. Alii I GrtnodDentofac Orthop 72: 665-70.

5 MAXILLARY CENTRAL INCISORS

CONTENTS • Aet io logy • Diagnosis • Treatment t iming • Attitudes to treatment• Treatment o f impac ted central inciso rs • Prognosis • Acute traumat ic intrus ion

AETIOLOGY

AI the age of abou t 6 yea rs, in most ch ild ren,a sudden and d ram atic cha ngeover occurs inthe anterior part of the dent ition, with theshedding of the deciduous inciso r teeth an dthe appearance of the pe rmanent incisorteeth. The first permanent teeth to erupt inthe yo ung ch ild arc usually the mandibularcentral incisor s, although the firs t permanentmo lars ma y sometimes prec ed e them. Themandibular lateral and the maxillary centralincisors then erupt at about the same time, at6.5-7 yea rs .

Und er normal circums tances, the max illa rylateral incisors ar c the last of the incisor s toeru pt, completing the ante rior den tition withtheir appearance abou t a yea r after the eru p­tion of the ad jacent cen tral incisors. The spec­tre of erupted lateral incisors, associated withthe non-appear ance of one or both of the cen­tral incisors, shou ld always be deemed abnor­mal, whether or not a deciduous centra lincisor is still present, and further investiga­tion should be und ertaken to ascer tain thereason for the aberration.

Congenital absen ce of a maxillar y perma­nent cen tral incisor, given the presence of per-

manent latera l inc isors, is excep tionally rare,alth ough it ha s been repo rted . In this situ­ation, the shape of the single cen tra l incisormakes it im possible to d istinguish whether itbelongs to the rig ht or left side. The pa tient'sappearance is abnormal (Figs 5.1a-c) andrather rem iniscent o f a 'dental cyclops' !

Obstructive causes

Supe rnumerary teeth

When an existing perm anent cen tra l incisordoe s not erupt and the diagnosis of impactionis made, the most com mon ncnologlc factor isthe presence of one or more mid line supernu­merary teeth (Howard, 1967; Brin et al. 1982;Zilberman et al, 1992) (sec Fig. 1.10 . In astudy of a sample of schoolc hildren (Brook,1974), the prevalence of su pernumera ry teethwas found to be between 1.5% and 3.5%. Ithas also been shown in a d ifferent samplegroup (Tay et al, 1984) that be tween 28% and60% of cases with supernumera ry teeth willhave result an t eruption d isturbances of theadjacen t tee th. By arbitra rily integrating thesetwo studies, it would seem tha t between

54 THE ORTHODONTICTREATMENT OF IMPACTED TEETH

(b'

Ia

Figu re 5.1

(a) Abnormal lip mo rphology, absence of ph iltrumand midline pos ition of sing!.' central incisor , (b)Intra -oral view of same patient to show 'squareanatomy of incisor and ind etermina te righ t/left des­ignation. The latera! incisors .1 Te late rally flared aspart of an otherwise normal 'ugly duckling' s tage ofdevelopment. (c) A vj ew of the palate to show bilat­era! submu cous clefting. (Courtesy of Dr 5 Ceron.)

(e)

0.42% and 2.1% of child ren su ffer fromim pacted cen tral incisor teeth from thi s cause.

Odontome

Among the other and rar er causes of obstruc­tion thai may eq uall y p reven t the eruption ofa normal cen tral incisor is an odontome.These arc vcry variable in size and type. bu t,w hether they are of the co mplex or co mpositetype, they usually have a broader a nd widercross-section, and their presence will be morelikely to prevent eruption of an incisor thanwi ll a su pern u mera ry tooth ,

Ectopic position of the tooth bud

The develop ment of a toot h bud in an abnor­mal positi on or in an abnormal angula tionmay have no apparen t cause, and may thusbe attribu ted to trau matic or genetic factors(Fig . 5.2). As the result of the d isp lacement,normally placed adj acent tee th may provide ap hysical obstacle to the normal eruption ofsuc h a too th. Alternatively, other p hysicalobs tacles, such as the above-mentionedsupern umerary teeth or odontomcs, may bethe reason . While the early removal of anobvious eetiologlc factor ma y be s trongly

MAXILLARY CENTRAL INCISORS

Fjgu re 5.2

All ab normally sited cen tra l illci.<;or, whose roo l apex isdose to the canm.. area. Th.. shape of the rool alsoappears 10 be abnorm al.

ind icated , th is will not necessarily affect theposition of the too th bud, which will probablycon tinue to develop in its existing loca tion .

Variation in the position of a developingtooth w ill produce a concomita nt va riation inits eru p tion path . When the eruption pa th isvery slightly defl ected , the too th will usuallyeru pt, bu t with an abnormal angulation of itslong axis, m irro ring the path that it will havetravelled . As its vertica l development p ro­ceeds, its relationship to the decid uous prede­cessor is more lateral, medial, ling ual orlabial. This will bri ng about a partial andob lique resorption along one side of the rootof the deciduous incisor. In d ue time , the fur­ther progress of the permanent incisor bringsit into contact with the CTOwn on that side ofthe decid uous too th.

The permanent toot h sometimes remainsimpacted , if insufficient space exists. Alterna­tively, the tooth may finally eru pt ad jacent tothe over-retain ed decid uou s too th, possiblyin to a crossbt te relationship, or it may be pro­dined labially, or a dia stema may be pro­duced in the midli ne. This situation may notbe self-correc ting, afte r the belated shedd ingor extraction of the stubborn decid uous too th.

Should the position of the developing toothbe more marked ly d isplaced , w hich isun usual, its potential eru ption pa th will be ina more ob tuse d irection, a nd litt le or no

resorp tion of the deciduou s tooth will occur.In these circumstanc es, eruptive movementsare minimal, and the pe rma nent too thremains in a more or less unchanged positionover a long peri od . Fina lly, when positivein tervention is undertaken, removal o f thecause will need to be supplemen ted withactive appliance therapy fo r its resol ution.

Traumatic causes

Obstruction due to soft tissue repa ir

The traumatic, sudden and very early loss ofthe deciduous incisor teeth is most often theresult of an accide nt that delivered a blow tod islod ge the tooth, usua lly whil e the childwas at p lay. The possibilit y also exists for thi sto have been caused by a dental ext raction,p rompted by the presence of deep caries orfollow ing the sequelae of an ea rlier trauma.This typically happens at 3 or 4 years of age,at a time when the permanent inciso rs are notread y to erup t and ,1 healing-over of themacerated gingival tissue occurred, withou tthe early eruption of the tee th. In time,changes take place in the connective tissueoverlying the tooth germ, wh ich preventsthem from penetrat ing the m ucosa (Dibiase,1971; And reasen and And reasen, 1994). Bythe age of 7 or 8 yea rs, one ma y see and beable to palpa te the bu lging profile of the cen­tral incisors (See Fig. 3.2.1).

Dilaceration

In the early stages of their development, hig hin the max illa, the perman ent central incisor sar e situa ted lingua l and su perior to the apicesof the deciduous incisors. As developmentp roceeds. their position changes. wi th labia land inferior migration. As this occurs, anoblique resorpt ion of the roo ts of theirdeciduous prt>dL'CL'SSI)fS is ini tiated.

During th is critical period , it frequent lyhappens that the child becomes involved in atraumatic ep isod e, in which ,1 blow is inflictedon the decid uous max illary incisors, from thefront, in a superior and pos terior d irection. If

55

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH56 ::..::...-----'=-----'-----'::..::...::..::...::..::...-----'== = -"

Figure 5.3

Thl' tangential view shows S<.'WIV labia l dbpla(t'ment ofthe ro...t of the deciduous incisor. (C"urll'Sy of Professo rJlU~Im.,n n.)

these teeth are displaced superiorly (intruded),it follows tha t a fracture of the alveol ar processhas occurred and that ei ther the teeth alone,or together wi th a part of the labi al plate ofbo ne, have altered their pos ition.

By and large, thi s displacement 'will cause alabial fracture of the bu ccal plate, and the rewill be an anterior displa cem en t of the rootsof the already superiorly and slightly palat­ally d isplaced teeth (Fig. 5.3). Th is usually haslittle effect on the unc rup«..'d permanentincisors.

Occasionally, however, the thrust of theblow is delivered in the direction of th e longaxis of the dec iduous teeth, and ma y be trans­mitted supe riorly to th e developing per­mancn t tooth . The resorbing roo t apexmomenta rily establishes a po int of impactwith the incisal ed ge of the crow n of the pe r­ma ncn t incisor. This w ill cause the crown ofthis unerupted pe rma nent inciso r tooth torotate u pwards, in its crypt. Since its root isonly partia lly developed at this time, th eformed part of the roo t will rota te w ith thecrown. However, any fu rthe r root d evelop-

ment tha t occu rs in the post-trauma periodwill often con tin ue in the same d irection asbefore, p rod ucing a bizarre angle be tween thepre-trau ma and post-trauma po rtions of thetoo th . This will produce the typical dilaoer­ated central incisor, with labial d isplacement.The site of this junctio n will depend upon th estage of develop men t of the root at the timeo f trauma, as will the prognosis of any p ro­POSI..>d orthod ontic treatment for the too th.

Pa latal, rather tha n lab ial, displaceme nt ofthe crow n vis-a -vis the post -traumatic roo tpor tion ma y occur in rare ins tances, as a va ri­ation of the above theme, a nd is due to amore palatal position of the tip of the devel­opi ng permanen t incisor relative to the apexof the de ciduous incisor roo t at impact. Thisis a more likely variation in the wry young,durin g the early calcification of the toothcrown when its palatal location is more p ro­nounced .

This scenario for the causa tion of d ilacera­tion is ex tremely well known, and p robablyrep resents a majority opi nion w ithin the p ro­fession. Ho wever, while this is not ruled outby other aut horities, othe r aetiologic possibili­ties do exist.

A developmen tal origin has been suggestedas an alte rnati ve (Howe, 1971), with the co n­ten tion that the acti ve process o f the develop­men t of cysts, odontomes or su pernumeraryteeth may p rod uce this p henom enon by d is­p lacem ent o f the crown of the too th or byin terference and redirect ion of its roo t. Nohistory of traum a could be elici ted in 70% ofanothe r sa mple (Stewart, 1978) nor couldmacroscopic or mic ros op ic evidence oftrauma, nor the existen ce of a cyst, odontomcor ext ra too th. No CtlSC wa s found with bothcentral incisors involved, nor was th ere dam­age to neighbouring teeth, which cou ld beexpected to occu r in at lea st a few instances iftrauma were th e cause. These cases a lso failedto show two d istinct and an gulatcd portionsto the roo t, but rather a conti nuous and tigh tCUrve (Fig. 5.4), qu ite d ifferent from those inwhom trauma, as an aetiologlc fac tor, wasev ident.

The conclusi on of the lat ter report was tha ta fai rly high proportion of d ilaccrations occu ras a resu lt of an ectopi c siting of the too th

MAXILLARY CENTRAL INCISQRS

Figure 5A

An ..xtracted dilaceratcd incisor.

germ, whos e root development is deformedby its proximity to and the ana tom y of thepala tal vau lt in the immediate vicinity.

These explanations are unsa tisfactory onseveral counts. Differen t cases sho w analmost id en tical and very typ ical anatomy ofthe tooth, which affec ts maxilla ry centralinciso rs exclusively, and virtua lly neveroccurs bila terally. The crown is norma llyshaped . and the coronal portion of the roo tshows initial normal developmen t. The a picalpor tion , however, develops along a circula rpath, in the labio-lingual pla ne, rather thantwo straigh t po rtions of root at an angle toone anot her.

No t only is the anatomy typi cal. but theposition and orientation of the too th is alsounique. The crown of the too th is di splacedhigh on the labial side of the su lcus, withou tlateral rotation, and its palatal aspect is palpa­ble close to the roo t of the nose. Often, theroot apex is palpa ble on the palata l side of thealveolus, and may be the sign tha t in fl uen cesan unwary surgeon to mistakenl y approachexposure of the tooth on the wrong side!

And reasen an d Andreasen (1994) have sug­gested that the loss of a decid uous incisormay lead to scarring along the eruption pathof the permanent incisor , which defl ects thedeveloping tooth labially. This runs coun terto Stewa rt's observa tion thai no history ofearly tra umatic loss of the dec id uou s toothhad occu rred in 709', of the cases.

There is an a lternative hypothes is. It is pos­sible to read a completely d ifferent netiologtcinterpretation into these constantly occu rring

feat u res, and it is pert inen t to beg in by qu es­tion ing the reliability of a child's or paren t'smemory regard ing traumatic in ju ry of thefron t tee th. Severe trauma is ra re and alwaysremembered, but no n-d isfiguring trauma (i.c.trauma that causes neither fracture nor di s­placement to the anterior teeth) occu rs quitefrequen tly in young child ren, is rarely notedand almos t never remembered in the yearsthat follo w.

Abrup t and vertically d irected forcethrough the long axis of the dec id uous too thwill br ing abou t the transference of theim pact to the inti ma tely related , unerupted ,permanen t central incisor. Because the longaxis of the perma nent inciso r ha s a mor e labi­ally tipped orientation , the force will be tran s­mitted in an oblique line that runs throughthe incisal ed ge and a point on the labial sideof the newly forming roo t, close to or at theroot- mineraliza tion interface (Fig. 5.5). Sincethe blow will be delivered d irectly to the sen­sitive cells of Hertwig's root sheath, via thekn ife edge of the incompleted roo t at thisin terface, conside rable damage may beinflicted w ith relatively low force values. Itwill be apprec iated that precision in d irec tionma y be more critical than force magn itude.

It is entirely possible that the roo t sheathmay only partial ly recover from the blow,which may resu lt in an attenu ated rate of p ro­duction of denti ne on the lab ial side of thetooth . With the remainder of the root-formingsys tem con tin uing to produce dentine un­sca thed, undeterred an d unabat ed . it followsthat the final shape of the root of this toothwill conform to a con tinuous Iabiallv d irec tedcurve (Fig. 5.6) , unt il apcx ificat ion isachieved . Furthermore, since the dentalpap illa base of Hcn wlg's root sheat h main­tains its po sition within the elvcolor p rocessfairly cons tant ly - against the eruptive forceof the developing tooth - and provides thep latform from which the roo t is d irected , thecrown of the incisor moves labially and supe­rio rly for as long as this asymmetrical roo tmineralizat ion continues . In other wo rds,d ilaceration of thi s classical type, is <In anom­aly that is trau ma tic in origin bu t develop­men tal in its final expression.

This hypothesis provid es an explana tion

57

THE ORTHODONTIC TREATMENTOF IMPACTED TEETH58 ___ _ _____ ---'--.::.==~.::.=.::.=_=__.:::_c.c.:.::.:.::::...:.::::C'_'

Hertwig's root

' -e,ath

Fig ure 5.5

A diagram to shew ho w a \'crtica lly direct..od forcethrough the decid uous indsor is tr..m~mitl....t to the labi,l laspect of the mineralizing roo t of the unerupted pcrma­lien! incisor.

for the typical appearance of the dilaceratedtooth, as well as its final unerupted positionunder th e nose. Furthermore, since it mayoccu r with a relatively minor degree oftrauma, thi s could account for the high pro­portion of cases with no appa rent traumaexperience . Its rela tive rarity may be due to ahig hly cri tical and specific positional relation­ship betw een the deciduous and permanen tincisors, at the time of in ju ry . This mayaccoun t for an absence of bilaterally affectedcases , for its non-occu rrence among lateralincisors and for an absence of any associationwith supemumer.1 ry teeth, cysts and odon­tomes .

Arrested root developme nt

When a preschoo l chil d suffers a very severeblow to the maxillary anterior dentition, thisis likely to res u lt in the loss of the decid uou sincisors, and may cause fractu re of one orboth jaws. The damage to the roo t-prod ucingring of cells that for ms Hertwtg's shea th mayhave been so ser ious as to ha ve effective lycaused the cessation of any fur ther root devel ­opment. These teeth may lose th eir erup tionpo tential, w hile the adjacen t teet h will con­tinue to eru pt. bringing with them verticalproliferation of alveolar bone .

Only at a much later stage will thi s pheno­menon be discovered, when th e affected toothor teeth do not erupt an d an area of verticallydeficient and bucco-palatally na rrow, edentu­lous , alveo lar rid ge is ev ident.

Rad iog raphs w ill us ually reveal the crownof the tooth to have a normal axial inclination ,but the tooth will be sit ua ted very high up inthe premaxilla, with minimal or no root for­mation, depending on how much roo t hadalready developed at the time of the acciden t.

Figure 5.6

A d iagrammatic ilIu..trano n of the• prog fl;>';..ive aIterationin th.., position uf .1 dilacera ted incisor, d Uring uncquillroot f\,rm,l li"". ;'\;01,' that the pos ition of Hertwlgs rool..h..-ath remains unaltered .

Acute traumatic intrusion (intrusive luxation)

Tra umatic injury occurs in young children asthe result of play-related acti vities in schoo land at ho me. in accidents involving a fall or,occasionally, as the res u lt of deliberate physi­cal vio lence (Andreasen and And reasen,1994). Effects on the teeth range fro m a transi­tory pu lp in flamma tion, through the various

MAXILLARY CENTRAL INCISORS

types of fractu re of the crown of th e tooth ando f its roo t, and, in the seve rest cases. avulsiono f the entire too th , Intrusion of one or more ofthe incisor teeth is often associated wi th afracture or comm inu tion of the lab ial plate ofbone and a tearing of the pe riodontal fibres.

A child may present at the emergen cy clinicwi th wh a t gives the appearance of a totalavulsio n, s ince the too th is not vis ible in itsformer p lace, the gingiva is lacerated an dthere is a co nsiderable amount of blood dot.A pe riapical radi ograph of the a rea willreveal a superior displacement of the too th,into the alveola r bo ne, without necessa rilyproducing a fracture of either the crown orth e roo t . The labial plate is d isplaced labially,although it is most often held close by theinjured but uninterrupted band of labial gin­giva an d soft tissue. The integrity of the bloodsupply 10 the soft tissues is usually intact, andthis allows good and rapid soft tissue healing .

In a sense, thi s tooth has been totallvavulsed, bu t inan atypical manner. It is corn­pletely d isplaced fro m its socke t, with a totalsevera nce of its attach me nt a pparatus and ad isrup tion of its vi ta l supp ly lines. Whe ncompared w ith the typ ical av u lsed case, how­ever, it has enormou s ad va ntages : the too thhas not been allowed to d ry, it has not been incontact with any form o f contam ina ted mater­ial, an d it is not nec es sary to store it in salivaor mil k or other recommend ed isotonicmedium before restoring it to its former place.It is situated in an area initially su rround ed bya coagu lating haematoma an d later by anorganizing blood clot, and it must beas sumed that the damaged periodontal fibresin this situa tion fare considerably bette r thando th ose of the replanted tooth, w hich hasspent some time ou t of the m ou th .

DIAGNOSIS

History

The patient' s med ica l his tory should be re­cord ed carefu lly. It must be borne in m indthat surgical interven tion is very likely to bean essen tial part of the treat ment that is to be

pro vid ed . Accord ingly, such aspects as previ­ous illnesses, pa r ticularly rheumatic heart d is­ease, drugs be ing presently taken andbleed ing tend encies, toget her w ith an y o the rimportan t and relevant item s o f information,must be elicited at the outset.

Question s should be asked with particu laremphasis p laced on the possibili ty of anepisode of trau ma . The paren t should beques tioned carefu lly to d iscover whether thechild is accident-prone, in ge ne ral. Directmention o f bicycle accidents, falling from achair, a ladder or a tree , or being hi t in themouth during play should be made, and a llrelevant answers should be carefu lly re­corded, together w ith the approximate datesof their occurrence.

Clinical examination

Much of the d en tal history is possible toascerta in from a glance at the d entition itself .The existence of sealants an d res torations, theabsence of teeth, gingiva l int1am mation andthe leve l of oral hygiene will of ten tell a greatd eal about past attitudes o f both the pati en tan d the attendi ng d ent is t to prevention and toth erape utic proced u res . The presence orabsence of the d ecid uous inciso r is generall yirrelevant. The cent ra l incisor of the op positeside an d the lateral incisor of th e same sid ewil l us ually be seen to be tipped toward s a ilean other, an d there will usua lly be insu fficientspace at the occlu sal level for the placementof the u nerup ted tooth . Widely d ivergentroots of the two ad jacent teeth will su ggestthe presence of an unseen and u ndiagnosedphysi cal obstruction .

Palpa tion

In obs tru cted cases, the u nerup ted too th itselfis often hig h on the labial side of the alveola rridge, an d there may be ad d itional an dsmaller irreg ularities bu lgi ng the a lveol usmore in ferio rly, w hich Me bes t id ent ified bypa lpation. There will almost always be a

60

labio-lingua l wid eni ng of the ridge. If therid ge Mea is relat ively thin in feriorly, this willind icate tha t teeth are no t p resent a t this level.

TIle importance o f pa lpa tion of the area isnot to be underes tim ated , since, if it is no tperformed with sufficient thoroughness, animportan t diagnosis may be missed . The pres­ence of a d ilacerated centra l inciso r will onlybe revealed by clinical examination if palpa­tion is made "cry high in the labial sulcus .Normally. the superio r mid line area is delin­cated by the pro minence o f the anterior nasalspine, on each side of which a shallowdep ression will be felt. The palatal surface of,1 dileccra tcd incisor crown faces forwardsand produces a hard swe lling in the placewhere the shallow depression is expected . Bysuperiorly ret racting the upper lip, the oralmucosa may be seen to mo ve freely over thestretc hed area, which w ill emphasize the out­line of the cingu lum of th e too th.

Palpa tion of a dilaccrn tcd central incisorma v often be made in two places. With theabnormal position o f the coronal por tion ofthe tooth, the further development of the rootportion may be along an axis that is tippedmore lingually, and , in the later stages of rootclosure, the apex may become palpable as asmall and hard lump in the pa late. This is afea tu re that few clinicians seem to look for,and is more consistent tha n may be realized(Seward. 1968).

Radiographic examination

In Chapter 2, the di fferent methods of radio­graphically viewing unerup ted teeth weredis cussed in genera l. and it was point ed ou ttha t a periapical view pro vided essentialqualitat ive info rma tion and . as such, shouldbe the first step in this part of the examina­tion.

In the case of an uneru p ted central incisor,this view will genera lly sho w associatedpa thology with grea t clari ty, includ ing har dtissue obs tru ctions (supem urnera ry teeth ofvarious types and cdcnrornes) , soft tissuelesions <Cysts and tumours), and abnormalroot and Crown morphology of th e unerup ted

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

tooth. From th is alone, it will usually be pos­sible to establish the reason for the failu re ofthe too th to eru pt.

If supernumerary teeth or odontomes aresee n on the film, the information tha t willthen be required relates to thei r size, theirnu mber and th eir mesio-d istal relationship tothe mid line a nd the inciso r tee th, all of w hichwill be obvious from this view. However,their labio-lingual orientation in rela tion tothe ad jacent erupted tee th will not be obviousfrom this one film. Since the periapical view isobliquely angled to the horizontal p lan e, alabial supern umerary tooth will appear lowerin the vertical plane than a palatal supern u­merary tha t is situated at the sam e height.Accordingly, the assessment of heigh t isdirectly related to the lebio-lt ngual po sit ion ofthe tooth.

At the age at which most pat ients willatt end for treat ment , a true lateral, tangenti alview is not helpful, due to the superimposi­tion of cen tral and latera l inciso rs, deciduouscanines and unerupted pe rmanent caninesand the supernumerary teeth . A second pert­apical view, d irected from a more d istal van­tage point, w ill usually help to localiz e therelative position of th e unerupted teet h, usingthe p rinciples of parallax. Similarly, a rou tine(oblique) occlusal film, w hich we earlierdescribed as a more stee ply angled pe riapicalview, will help to separate out the images ofthe unerupted teeth, using the same pa ralla xprinciples, this time in the vertica l plane. Thiswill then provide the information needed tocompu te the relati ve heights of the indi vid uals truct u res .

A good vertex occlusal film, di rectedthrough the long axes of th e anter ior teet h,will provide une quivocal ev idence of labio­lingu al too th position, particul arl y if th ere ism arked d isp lacemen t.

Dilnccrntcd central incisor teeth \v ith labiald isp lacemen t have a very special and charac­terist ic appearance on a periapical radi ograph.We have already descri bed that the crown andth e developed part of the roo t were rotatedlab ially and superiorly at the time of thetrauma or pursuant to it. The long axis of thispout of the too th lies in the di rect line of theX-ray beam, which is d irected at ,1 periapical

MAX!LLARY CENTRAL INCISORS

film of the area, and accordingly will show upas a cross-sectiona l view of the crown, super­imposed upon a cross-sectiona l view of thewidest part of the root. The apical (post­trauma ) port ion of the root, on the other ha nd ,continues to grow roughly along its originalcourse. It will the refore be read ily u nd ers toodthat the labial su rface will be seen to facesuperiorly and the cingulu m dearly outli ned.in feriorly. The roo t apex will be see n as a ve ryshort 'tail' extending superiorly above thetooth's labial sur face. The p icture is reminis­cent of a scorp ion, viewed from the fron t.

Although this is clearly recogniza ble, thefilm g ives only an indica tion of its height inthe alveolus, wh ile its gen eral apico-lncisalori entation cannot be defined . Confirmationof the d iagnosis may then be positively made,using a tangential or lateral sku ll radiograph.This will give information that will hel p tobuild up a more comprehensive p icture of thetoo th, particu larly regarding details o f itsmorph ology, its heigh t an d its overall long­axis o rienta tion.

TREATMENT TIMING

In Chapter 1, we discussed the occu rrence o fa cha nce pa thological finding during routineX-ray examina tion. Obstructions should beremoved wherever possible before they ha vethe cha nce to create a situation o f dela yederuption, in order to obviat e the need foror thodontic treatment. There is, however, nopreventive treatment to be reco mmend edonce trau ma has generated the dila cerat ion,and the pa tient will need to wait for the timewhen corrective treatmen t is ap pro pria te.

Wh en a patient presents with a sin gle cen­tral incisor an d both lateral incisors eru pt ed,the normal eruption date of the second cen­tral inciso r will have passed . The impactedtoo th will be see n on the periapical radi o­graph to have at least two-third s o f its roo t,the d evelopm ental land mark that determinesthat a too th shou ld be eru pted. Orthodonticand su rgical treatmen t are therefore indicatedat that time, both for obstructive impactionsand for the d tlacerated tooth.

Often, at this early sta ge, on e may be ableto foresee an obvious need for orthodont ictreatment for other reasons - treatment thatmay not normally be advised until 3 or ofyears later. It is not reasonable to delay theresolution of an impacted central incisor forthis period of time merely in the interests oftrying to achieve a single-phase orthodontictreatment plan in the full pe rmane nt dcnti­tion .- The alig nment of the impacted toothshould be undertaken and execu ted effi­cien tly, av oidi ng u nnecessary a ttention toothe r d etails. Root uprighting and torqueingshould be pe rformed as indicated , but anideal final an d artis tic alignment is not theaim at this s tage.

Once ap pliances are removed , followingthe restoration of normality, there will be nat­ural spontaneo us changes in th e alignment ofthe se teeth during the man y mo nths that fol­low an d before the permanent canin es comeinto their place. It must be po inted nut to theparent that th is is expected to happen, andthat it is normal an d not a subject for co ncern .The parent a nd pa tient should be ad vised thatfurther treatmen t will be necessary at a laterd ate, for the remainder of the overall maloc­elusion. and that retention of the alignedincisors agains t these physiological move­ments is no t advised .

ATTITUDES TO TREATMENT

There has been a more or less standa rd p ro to­col of trea tmen t available for severa l decadesin the orthod ontic p ro fess ion in Europeregarding normally developing bu t impactedcentral incisor teeth. The recommendationsad vise

(a) that ad equa te space be prepared for thetoo th in the arch, and

(b) that the cause of the non-eruption (us u ­ally a supern umerary too th ) be elimi­na ted .

The im pacted central incisor teeth shouldthen usually erup t spontaneously (Battagcl.1985; Hou ston and Tulley, 1986; Mills , 1987;Mitchell and Bennett, 1992). In the absence of

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH62 ~:..:::======.:..=...:::::_==_=:::

adequa te sp.lee, it has bee n reported thateruption rarely occurs (Dibiase, 1971).

Studies that have been made of patie ntswho ha ve u ndergone this type of trea tmenthave shown d isa ppoint ing results withreg ard to th ree important para me ters.

Non-eruption, Spontaneous eru ption hasbeen variously reported as occu rr ing in54-78% of cases (DiBiase, 1971; witsen­berg and Boe rtng, ]981; Mitchell andBennett. 1992), which represents a lowdegree of re liability of the method.

2 Dday in eruption. Even when eruptionoccurs, the average tim e for the affectedtooth to ma ke its appearance in themouth is be tween 16 and 20 months(Bodenharn, 1%7; DiBiase, 1971; Mitchellan d Benne tt, 1992). Th is is an unaccept­ably long period of lime when on e con­siders that th e patient will be wi thou t afront tooth or tee th fur so many months.Ad d itiona lly , 25% of the patients neededto ha ve two su rgical ep isodes, followedby a wa iting period of 2.5--3 yea rs beforethe tooth erupted (Mitchell and Bennett,1992)! In .1 retrospective s tudy of cases inwh ich (.1) space had bee n p rovided, (b)the su pe rn u mera ry tooth had beenrem oved and (c) a stainless s teel crownha d been cemented to the impacted too th,eru ption was found to have occurred in96% of the pa tients. However, thisrequired an evorcgc time span of 3 years(Mun ns, 1981)!

3 Aligl1l11t'1I1. The third parameter th atshowed di sappointing resu lts relat es tothe ade quacy of spontaneous alig nment.Of the inciso r teeth that did erup t (64%)in the s tudy of Mitchell and Bennett(1992), 59% were found to align them­selves reasonably we ll wi thout the use ofap plian ces an d 41% req u ired the use oforthodontic appliances to achieve the res­o lut ion o f rota tions and root d isplace­ment. According to Gard iner (1960,however, spontaneous alig nment occurson ly in a minority o f pa tients. Clearl y thecr iter ia fur d ecid ing what cons titu tes anacceptable 'alignmen t' varies from oneclinician to ano ther an d, on e may be per-

mined to specu late, upon whether thetreatment is being carried ou t in acommu nity health clinic or in a privateorth odontic practice .

Some worke rs (Day, 1964; Kettle, 1958;Hotz, 1961) recogn ized the need for a ffirm a­tive action to control (i.e. actively encourag e)incisor eru ption, and devised methods to per­form this, us ing w ire loops and p inning, andeven ad vocated the passing of a wire th ro ugha drilled hole in the incisal edge in those earlydays.

Mills (1987) warned aga ins t the ex posure ofthe crown of the permanent tooth during theprocedu re to remove the supern umerarytoo th, warning that pe riodontal progn osis ofthe final result would be compromised .Beyond the use of a sim ple removable ap pli­ance to make space in th e arc h fOT theunerupted incisor, he displayed a ret icen ce touse mechanotherapy, an d seemed to haveinfl uenced opinion in Britai n, w here thereappea rs to be a wide consensus that the uSC' ofapp liances in bri nging d own impacted centralincisors is something to be avoid ed. His rea­sons for this attitude are as follows:

(a) th ese teeth of ten eru pt spo ntaneo us ly,w itho u t help;

(b) loss of labial bony pla te;(c) poor g ingival ma rgin, with less att ached

ging iva;(d) gingiva l level d iscrepa ncy .

Little object ive research is offered in su ppo rtof these contentions, and it is equally opento speculation that most or all of thesefactors could be adver sely affected by over­enthusiastic or ot herwise pOOT su rgical tech ­niqu e (Becker ct ill, 1983; Koh avi et al, 1984).This issue is d iscu ssed fu lly in Chap ters 3 and6.

A minority of child ren with most otherma locclusions arc rarely brought to the ortho­dontist mu ch be fore 10 or 11 years of age, yetthe ma rred appea ran ce of the child with a sin­gle erupted centra l incisor generally encour­ages the parent to seek trea tmen t muchearlier. An orthod on tist' s lac k of concern for arapid solu tion, in respunse to the parent's d is­quiet for the ch ild's comp romised ap pear-

MAXILLARY CENTRAL INCISORS

ance, is insensitiv e, if not callous. This is par ­ticu larly d isturbing in the present context,since simple and effective means of achievingth is end are freely ava ilable.

TREATMENT

Following a determ ination of the overallorthod ontic d iagnosis, a problem list sho uldbe drawn up. Occasio nally, there ma y be justone item on the list, namely the impactedtoa th. More often, the presence of mandibularinciso r crowding, pos terior crossbite or a class2 relationship may also be noted, and the clin­ician mu st then decide which of these is to betreated in this early treat ment phase andwhich is left un til later.

As a general ru le, treatment priority shouldbe given to the unerupted incisor, and allother or thodontic procedures delayed untilthe incisor has been brought in to alignment.However, an an terior or posterior crossb iteand malalignment of the eru pted incisors willusually be treated at the same time as spa ce isbeing provided for the im pacted incisor tooth.

An orthodontic appliance for use in theearly mixed dentition

As has been po inted out, opening the spacefor the unerupted tooth prior to removal ofthe supernume rary req uires some form oforthodont ic appliance. The simple removableplate is manifestly unsuitable, since the onlypos itive influence it is capable of producing isa lateral tipping of the ad jacent teeth. Whilethis creates spa ce in the arch, it does so on lyat the corona l level. The effect is quite theop posite more apically. where the roo ts of thetipped teeth will be moved towards oneanother and di rectly into the path of the (it isto be hoped) erupting impacted tooth.Vertical force control on the impacted tooth isd ifficult to achieve with a removable appli­ance. Corrective rotatory movement of thefinally erupted too th is rarely adequa te, whileuprighting and torqueing root movemen ts

are qu ite im possible. A practitioner using thismethod would essentiall y be placed in theseat of an observer, being able to exercise vir­tually no control over eruption, which is themost important aim of the exercise.

It is true that in the eve nt that the too theru pts (a) spo ntaneo usly and (b) into goodalignment there has been much to gain by thisrelative inactivity, apa rt from the unreason­able dema nd on patience that is made of thechild , who may be without a front toath for avery long time.

An impacted tooth init ially shares the lim­ited labio-Iingual wid th of the alveolar ridgewith the supernumerary tooth, wh ich pre­ven ts its eruption . Sharing this space usuallycauses the roo t of the cent ral inciso r tobecome displaced in either or both the labio­lingual and mesio-d istal planes of space. It istherefore likely that, in the final analysis, theeru pting tooth will require root movement ina labio-lingual (torqueing) and /or in a mesio­distal (uprighting) direction , and this may beaccompanied by the need for significant rota­tional movement.

It becomes evident that a completely d iffer­en t type of appliance is ind icated - one thathas the potential to deal efficiently with allthese eventualities. Given the significantlyhigh num ber of cases ".'here eruption has prO"­duced an unsa tisfactory alignment o r whereeruption has failed completely, it is essentialto seek an alternative method of mechano­therapy that provides simple and rapid solu­tions to all the mo vements req uired .

A technique mu st be employed that pro­vides sa tisfactory an swers to the followingfou r aspects:

1 The ap pliance should have the capacity tolevel and rotate the adjacen t teeth rapid lyand, with cont rolled crown and roo tmovements, to open adequate space toaccomodate the impacted tooth. Thisspace is demand ed bot h <I t the occlusallevel and for the entire len gth of the rootsof the ad jacent tee th.

2 The surgical exposu r(' o f the crow n of theimpacted toot h, together with the bond­ing of a n attachment, requires to be per­formed in a manner that will achieve a

THEORTHODONTICTREATMENT OF IMPACTED TEETH64 ---.::.::.::======-=-====

good periodontal prog nos is, as descr ibedin Chapter 3. The appliance must hold thespace during an d after the surgical proce­d ure.

3 Light an d co ntrolled ex trusive forcesmust be generated fro m the appliance towork over ,1 long range of movement, tobring the too th dow n to the occlusallevel.

-I Final detailing of the position of theimpacted too th and its erup ted neigh­bours must be comp leted withou t cha ng­ing to a nother a ppliance. indudingmovement of the crowns and roo ts ofeac h o f these tee th in all three p lanes ofspace.

While it is important that the ap pliance hasthis facilitv, we have referred to cases w here,a t an ea rl}' stage of dental development, it isnot wist.' to achieve the ' final' a lignment of theideal adult dentition. Thi s is particula rly sowhen the permanent canines are very highand in close rela tion with the ap ical third ofthe lateral incisor roo ts.

Typically , ou r young affected pa tient hastwo molars an d no more than three incisortee th of the eru p ted maxillary permane ntdentition. The decid uous canines and molarsha ve insu fficient crow n heig ht and un favour­able anatomy to all ow the placement of afixed m ultibrnckctcd appliance. Fur thermore,there is rarely an y need or intention to movethem. Accord ingly, mo s t practit ioners side­step them an d band only the molars, w ithbonded brackets on the incisors, leaving along span of unsu pported wire in the buccalregion - the 'two-by-four' appliance.

In the early inciso r-ali gning stages, thearch wirc mu s t be of fine gauge. Distor tion isdi fficult to avo id , and cons equen tly the align­ing activity of till' wire is nu llified . Because ofthe long Sp<1I1, there call be litt le effec tive ver ­tically ex tru sive force d irected from th e mo lartubes, ev en when the archwi re ga uge is sub­s ten tially increa sed . An chorage for the extru­sive movement of the im pacted too th isthe refore poorly exploited, and is lim ited tothe ad jacen t incisors, which progressivelyintrud e as the treatment p roceeds.

Johnson's (modified) twin-wire arch

An upd ated vers ion of the obs ole te and large­ly forgotten Johnson twi n-wire appliance(Johnso n, 1934; Shepard, 1961) p resen ts cer­tain unique feat ures that make it especia llysuitable and efficient in the many treatmentaspects of this speci fic p roblem, particularlyregard ing anchorage in the vertical plane.

The a ppliance is based on fixed molarband s, intercon nected by a soldered palatalarch (Fig. 5.7). Lo ng narrow-ga uge (0.020"

,.)

'b}

Figure 5.7

(<I) An ' ....dU~1 1 vi,'w of [ohnson's (mod itit'd ) tw in-wirea rch , to sho w the sn kh'rt'd p'11<11,11 arcb. (b) 0 ,020" roundtube s\"C tinns ,HC slotted in to the {).[}3(," round molartubes. The an terior sectiona l archwire in this case is a sin­gle 0.016·' wire. since on ly on",erupted permanent incisoris presen t and the usual multistranded wire is notneed ed . The alignment of the buccal tubt's shows ,1

downward tip as they proceed ml'Si<lUy, to encourageopen bite closure and to aid the mechanically i1ssisll-deruption of the impacted toot h.

MAXILLARY CENTRAL INCISORS

in ternal d iameter) tubes slid e freely in theround molar bucca l tubes (0.036"), and aremade to extend anteriorl v to the deciduouscanine area. An initi al a~lterior m ultis trandsectional wi re (0.0175") is held into the longnarrow tubes by a friction fit, created by plac­ing three or four bends in the multistran dcdwire an d then d rawing it through the tubebetween two grooved pliers. Whe n the appli­ance wa s in genera l use, several d ecades ago ,an d in compliance with its name, two fine0.010" stainless steel wires we re used in thean terior portion, to provide im proved flexibil­ity an d springiness, whic h todey's multi­st rand wi res achieve to a considerably hig herdegree.

The first step in the construction of theappliance requires that an impression of thed ental arch of the pa tient is tak en, wi th p rop­erly ada pted plain molar bands in place. Thebands are removed carefully fro m the teethand reset into the impression be fore pou ring .On the mod el, a palata l arch is fab rica ted andsoldered to the lingu al side of the molarban d s, to provide resistance 10 the ext rusiveforces that will be need ed la ter. Buccal tubesare best soldered to ensure precise alignm en twith the an terior bra cket position. Slightupward or d ownward tip pin g of the molartubes, to su it the needs o f an ind ividual case(Fig. 5.7b), will create a s ignificant intru siveor extru sive ver tical force co mpo nent on theanteri or teeth . The labial archwi re is con­structed on the mod el, initiall y using a m ulti­strand wi re in the bu ccal tubes.

The appliance is tran sferred to the mouthand cemented in pla ce, brackets are bo ndedto the anterior tee th, an d the prepared initi alnrchwtrc is pla ced . The brackets may be ofvir tua lly any type, al th oug h th ere are severalinherent ad vantages to Bcgg bra ckets in thissitua tion. Their ve rtical slot makes the m par­tlcularly suited to the light vertical tractionthat may need to be applied to encou rage theeruption of the impacted tooth .

By the secon d or th ird visi t, some weekslater , alignm ent of the three eru pted incisortee th will u su ally have been achieved, andthe mulfi strand ed wire is d iscarded . It isreplaced by a plain round s tainless steel0.016" (for Begg) or O.Ol S" (for Edgewise)

wire, which is similarly inserted in the longnarrow -gauge bucca l tubes. An expanded coilsp ring is thread ed on it and tied into the ante­rior po rtion, compressed be twee n the tee th oneithe r sid e of the impacted too th .

Space is gained very rapid ly. If edgewisebracket s are USl'CI, the mo ve men t will be atleast partly by tipping, an d subsequentuprighti ng will need to be perform ed with aheavier ga uge wire o r using auxill iaryspri ngs. Once there is adequate room for theunerup ted tooth an d uprig hting has beenachieved, a piece o f s ta inles s s teel tu bingshould be th read ed onto the e rchwirc. thelength of the lu be being cut so that it fitsexactly be tw een the bracke ts of the teeth adja­cent to the impacted too th . The presence ofthe tubing between the adjacent teeth ensuresmaintenance of the req u ired spa ce an d con­tributes to the rigid ity o f the archwire. Th is intu m provid es a finn pla tfonn from whichlight force may be applied to the uneruptedtoo th.

At this point, the pa tient is read y for thesurgical episod e, in w hich the retaineddeciduou s incisor an d bu ried su pe rn umerarytoo th are remo ved. The perma ne nt incisor isexposed an d an at tachment placed . All this isach ieved without removing any part of theorthodontic appliance.

If th e patient is seen eve ry 14-21 da ys forad justment, a p reviously obstruct ed toothw ill usu ally eru pt very rapidly, an d wi thinweeks it will be visible, to provid e the youngpatient with a mort' acceptable appearance,w hich will enhance his or her self-confidenceand self-image. The favourable time factor isan advantage that shou ld not be u ndcrcsti­m ated. and one tha i need s to be taken in toaccou nt , even w he n treating the youngerpa tien t. A dllaccrntcd incisor will tak e longerto resolve, but the treatment p rinciples are thesame (Figs 5.8 and. 5.9).

At the point wh en th e tooth reaches theocclu sal level , a reassessment is ma d e CiS towh ether uprigbttng. torq ueing or ro ta tion ofthe too th is need ed . If so, the eyele t isremoved and a brac ket simila r to that on theother teeth is placed in its id eal positio n.Fin ishing is then achieved in the a ppropria tema nner (Fig. 5.10).

65

66 THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

Figure 5.8

A diff<;>/Vnl patient is shown here 10 illustrate SUrgical exposure and attachmentbonding afte r adequate space has bee n reopened.

,.,

(d

(b'

ou

Figure 5.9

(a) Fu ll ffig.lgemen t of the wire in the bracket increa ses th.. verticaltraction compo"",,,!. (b) 45 months f'O"'l~urgf'T)', fol­lowing three visit.. lor adjustmt'nt.the Impacted central incisor is p alpa ble mo re' inferiorly. A bracket has been placed onthe newly t>fUptt"d lateral inOs."r . Ccl9 months po,;h urgery. th" tou th is Wt ,n O!TUptro an d labially di ..p laced and rota ted .(d) 11.5 m,mIQ'i post-surgery• adequate ali~nml'nt hots OC'L'I\achie...-ed.

MAXILLARY CENTRAL INCISORS 67

C,I

,,

o»

Cd en

rtac-es.to(a,b) Tangential views of the anterior m,lxill,l uf cnsc iIIu~lrMl'<i in Fi)lj~ 5.7 an d S,Y to show the ( iI, l' before and aftertrt'ntml'n t. (c) Thl' p l'riapic,11 view uf the case Immediately prior to appliance removal. Careful examination of the rout ufth e pr eviou sly impa cted left cen tral incisor will reveal that the apical thi rd of th e TO..,t is p,H,l11d to the central X-raybeam. The roo t may be of normal length . (d) The peria pica l view 14 mon ths attor completion of trc.um..-nt .

The orthodontic treatment procedure isvery simple, and docs not requ ire a high levelof expe rtise. The laboratory stage of applia ncecons truction requires accurate soldering ofthe pal atal arch and careful alignmen t of the

buccal tubes, which a good orthod ontic tech­n ician should ma ster very q uickly, althoughthe orthodontis t may prefer to do this himselfor herself. In the mouth, cementation of thebands and bonding of the brackets is routine,

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH68---- - - - - - - --- - - - - - - - - -end the applicati on of the prepared archwirep resents a neat an d rob ust appliance in thelong span be tw een the molar tubes an d theincisor brackets, while anteriorly providi nglight and gentle vertically directed forces ofgood range, to give rapid results. The p res­en ce of the palatal arch w ill ensure that unde­sired movement of the adjacent incisors andthe distant anchor mo lars cannot occu r.

In commo n with other pa tien ts w ithunerupted incisors, the patien t with arrestedroot development will usu ally seek ad viceand treatmen t before the age of 9 years. By

,.,

contrast, however, in these cases mo re th anone and oc casio nal ly all the max illary inciso rsmay have been similarly affec ted . While thep rinciples of treatment arc the same .1S for thepatients we have already d iscussed , it is clea rthat, in the most severe of cases . even a p,lT­tiall y bra cketed fixed appliance m.1Y be inap­propriate.

In o rder to overcome the problem, a hea vybuccal arch wire of 0.036" (0.9 mm) ga uge maybe fitted into simila r-gauge round lubes onmo la r bands ca rrying a soldered palatal arch(Fig. 5.11).

(1))

'"

(J)Figure 5.11

(a) This v-year-old ch ild hil~ 1".,1 alveola r bo.lllL' height <lfte r avulsing hi"anterior deci duou s teeth .11 ,l~l' 2 years inan accident. Ib, cl The panor amican d latera l cephalometric film....ho,," '"l'rY lilli e roo t development of allrna-:iIl,lTy inci.50.,r;. Tlw cent ral incisors are ill the level of the anterior nasalspine. (d) Vicw uf sohh· wd pitl'''il l arch. (e) The toosors are surgicallyexposed . 1'01(' the la rge ,\11' .1., of hypopla..tic enamel . (f) Eyelet attachmentsarc bonded. (g) Alit'!" su tu ring..., sclf-..;upport ing 's topped' labia l arc hwire is

MAXILLARY CENTRAL INCISORS

(h)

(j)

plan -d in to the mola r tubes. Displ.l«'d superiorly by gcnt l.: (inllcr pressure, the anterior part of the archwire i.. en..nan-dby all fou r steel pigtai ls, to deliver eXlrusiw fora". Ih, i) Tangential and anterio r occ lusal radiographic views Immedi­at ely post-surgery. (j) A clinica l view at comp lo.,t inn o f trea tment. tFigu n' 5.11 colltiPlIltJ)

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH70- - - - - - - - - - - - - - --- - ----(Figure 5.11 ((Illli/wedl

(k)

m

Ik, Il I'ertapical and tangential radiographs at completion uf treatment. :'>:ote poor dl'n·lopmenl...an..tomical form andlife expectancy of the teeth at the cnd of tn.'atmcnt. Lprighting of ttl\' mnt.. was considered ina pp ropriate.

MAXILLARY CENTRAL INCISORS

At the completion of thi s phase of treat­men t, and for all of the types of problemdescribed here, it is good practice to perform,1 reassessm en t of the overall orthodontic con­dition . Further trea tment may be advised atthis stage, as mentioned earlier. More fre­quentl y, however, the appliance is removedand the pa tien t is placed on recall over ape riod of several years until the eruption ofthe full permanent dent ition, when a newclin ical assessemen t is made and an overalltreatment plan is developed for the entiredentition .

PROGNOSIS

The obstruc ted impaction

The prognosis of the resu lt is depend ent onseveral factors.

Root length

The root lengt h is almos t always norma l inimpacted teeth, al though in some cases theroo t may be somewhat shorter, owing to thecramped circu ms tances in whic h the rootdeveloped , p rior to treatment. Nevertheless, amild degree of shortening w ill not normallyad versely affect p rognosis.

Type and height of periodontal attachment

If the su rgeo n o pened a window in the oralmu cosa d irectly over the impacted tooth,above the attached gingiva , then the progno­sis of the result w ill be relatively poor . Stepsshou ld taken to manage the muco-ging lva lso ft tissue properly, by lifting a full flap fromthe crest of the ridge at the time of the surgi­cal exposure and fully resut u ring the wound,at the end . In this wa y, the tooth will comedown with a normal band of attached gin­giva, and the periodontal result will be good.

Relative bone height of the crestal alveolus

In Chap ter 6, we shall show that when teethMe su per-eru p ted, their vertical mov ement is

accompanied by a vertical increase in thealveo lar bone associated wi th them. Thus,w hen the impacti on of a tooth is resolved byaugmenting the nat ural eru ptive force, fol­lowing the removal of the causative agent, itw ill be seen that the bone support of thattooth will be greater tha n tha t around nor­ma lly eru p ting ad jacent tee th (Ingber, 1974,1976; Stern and Becker, 1980; Kohavt et al,1984; Melson. 1986). However, this positiveres po nse on the part of the alveola r bone tothe extrusive forces is dependen t on theamount of pressure applied being within rela­tively narrow limits. A periapical rad iographtaken at that time w ill show radiolucen t areaswhere new bone is being laid dow n - newbon e does not show up on X-ray. However, asimilar view taken 4-6 months after cessationof this movemen t, when the bone will ha vematu red and calcified , will show the excel­lence of its regeneration .

In the event that excessive extrusive force isbrought to bear on these tee th, eruption willalso occu r rapidly, but it will occur withou tregeneration of alveola r bone. The result willbe characterized by the tooth having a longclinical crown and conside rable mobility. Aperiapical radiograph performed even 6months later will show a much red uced bon elevel around the newly and apparen tly su c­cessfully resolved impaction. The prognosisof such a tooth will be impa ired .

Preservation of vitality

During the surgica l p rocedure, removal ofaw kward ly placed supernumerary teeth maycau se dcvitalization of the impacted tooth.Th is is qu ite unusual, ho wever, and it is morelikely that excessive extru sive forces, whichmay be negligent ly applied to eru pt the tooth .This compromises its bony suppo rt, and w illalso bri ng about the demise of its pulpal tis­sue.

Oral hyg iene

During the initial phase of eruption of animpacted tooth, the surroundi ng gingiva is

71

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH72 -..::.::..:::-..::.:=-..::.:===---=--..::.:---=-=-=_

sens itive, tender and bleeds very easily. Th iswill usually make the yo unger patient veryapprehensive of brushing the area on a regu ­lar basis and to an ad equate standard ofcleanliness. Secon da ry inflammation of thegingiva and it concurren t adverse effect onthe regeneration o f bone will be the inevitableres ult.

For these reasons. care shou ld be taken inthe proper p lanning and execution of the sur­gical techniqu e a nd in the application ofextrusive forces w hose magnitude are d iffi­cult to control. Elastic ligation thread is usedwidely for applying traction to im pactedtee th, by tying it directly a nd tightly betweenattachment and a rela tivel y rig id archwi rc. Itis exceptiona lly difficult to properly judge theamount of force being ap plied by thisme thod, and so, when it is the only practicalone available, great carl' should be taken notto til' too tightly. Wherever possible, alterna­tive method s should be used, as described inChapter ..I.

Vertical 'bo x' elasti cs arc often used inorthodonti cs to enha nce lntercuspation at theclose of treat ment , in routine cases. Theseclastics arc small a nd ca n produce forces verymuch in excess of thnt desirable for a singleimpacted too th, and these will be increasedstill furt her by mouth openi ng. It is difficultto measure or con trol the forces applied inthis way. Nevertheless, thi s is a valuable tool,and sho uld be used w ith only the very light­est and larges t of elastics. It shou ld also beremembered that . as orthodontists. we are aptto apply more th an adequate extrusive forcesby th e downward deflection of an archwire,and we then place a 'box' clastic, in addition,just to be sur e! The aggregated force becomesvery mu ch in excess of the physiological lim it.

Impaction due to trauma

Soft tissue obstructio n

The on ly treatm en t nccdc.....i to overcome thercsisten ce of the thickened mucosa to erup­tio n is su rgical, and was desc ribed in Chap ter3.

The dilacerated central inc isor tooth and theincisor with arrested root development

It is clear tha t the long-term prognosis ofmany dila ccra tcd teeth and teeth witharres ted roo t developm en t is poo r and theirextraction and replaceme nt is proba bly a pa rtof the long-term treat ment strategy. Thisbeing so , the mos t pertinent of questions thatneed s to be asked rega rdi ng the d ilaccratcdtoo th is whether it is worth it.

The answer to the question is not necessar­i1y the sa me for every case, and each must beconside red on its own merits. -No decisionshould be made until the p ractitioner firs tconsiders the following po ints in relation tothe particular patient concerned.

(a) A pe rmanent artificial solution cannot beconsidered much before early ad ulthood,whether by conventional prosthod ontictrea tment or implan t-bo rne restoration.

(b) Any tissue-bo rne for m of temporaryreplacement (partial 'flipper' denture)will be far less sat isfactory from everypoin t of view.

(c) Any too th-borne, resin-bonded br idgereplacement may requ ire so me prepara­tion o f the adjacent tee th, and may beunreliabl e in the long term (Boyer andWilliam s, 1993).

(d) Follo wing the extraction of the d tlacer­ated toot h, the alveo lar ridge area is defi­cient both vertically and in its labio­ling ual width, making the case unsuitablefor an im plan t and unaesth et ic for a con­ventional bridge.

(e) Orthodontic alignment of the d tlaceratedtooth will bring with it much alveo larbone, to enhance bot h ridge wid th andvertical heigh t, to normal dimensions.

(f) The retention o f even <1 very short-rootedand endodon tically trea ted tooth will p re­se rve the norma l shape and ar chitectureo f the alveolar rid ge.

Under these condi tions, or thod ontic align­men t of the impacted and dilarera tcd toothwill usually be prefe rable, even if sp lin ting o fth is compromised too th is needed to give itsupport. For the most par t, however, th is pro­ced ure must be loo ked upon as provid ing

BI8 LJOTHE'QUE: DE L'UN1''ERSlT~OS: F'ARIS V

U.ER. D'cO)ou rOLOGI '=1 . T1J ) ::-, I ~ rv' ''x

92 12 0 :~ lI,JNTHOUG E

MAXILLARYCENTRAL INCISORS

only a tem po rary solution, and, a t a latertime, w hen growth has ceased and cond itionsare more favourable, so me form of pe rmanentres tora tion will need to be considered.

Ap ica l root d ilaceration

In the very young pa tient, trea tment of thedila cerated inciso r follows much the samelines as described for the obstructed incisor.Before this is don e, however, a carefu l s tudyof the tangen tial rad iograph may reveal the.shape and orientation of the root. The moreapica l the d ilaceration vis-a-vis the coronalthird of the roo t, the better the prognosis. Onthe other hand, if the d ilaceration is in thecrown of the tooth. the prognosis improvesthe closer it is to the incisal edge.

If the d ilaceration is situa ted apical to thecoronal third of the root. orthodontic alig n­ment will p rovide an excellen t prognosis. Thetooth should be surgicall y exposed and aneyelet bonded to it. In most cases, the onlysurface of the crown that is availab le for theeyelet is the palatal surface. This faces theopera tor when the tooth is first exposed,while the ana tomically labial surface of thetooth is inaccessible, facing superiorly andposteriorly and buried in the hard tissue ofthe an terior nasa l spine (Fig. 5.8).

A stainless steel ligature is threaded throughthe eyelet. twisted into a pigtail and d rawndownw ards, to be ligated to the main ar ch­wire with a horizontal elas torneric mod ule, asdescribed in Cha p ter 4. Care should be takennot to apply mu ch pressu re ini tially, sin ce thetension introd uced by su tu ring the surgicalflap may itself apply a considerable dow n­ward force to the tooth in the first few weeks.

As the crown of the toot h responds to theforce, it rotates do wnwards marc and more.At the same time, the root ape x rotates for­wards towards the labial plate of bone. Ingeneral, the case may be com pleted withou tthe root apex ever becom ing palpable in thelabial sulcus. Only in exceptional circum­stances, w hen the roo t curvatu re is veryacute, will this poss ibili ty become a reali ty .

If the apex is prominent and further lab ialroot movement is still desi rable, this willnecessitate a surgical interven tion, performed

with the aim of amputating the root apex ofthi s tooth. The labially d irected po rtion of theroot. corres pond ing to the post-tra umaticdevelopme ntal portion. is section ed in a linethat is con tinuous with the labial side of themain coronal po rtion of the root of the too th.The pulp is extirpated and the root canal isobliterated using a combined conventional(coronal) and retrograde endodontic approach.wherever possible (Fig. 5.12). Further extru­sion and appro priate root to rqueing of theinciso r may necessitate a second roo t-sho rten­ing proced ure. but, if the first proced ure wasdelayed. as late as possible and the roo t ape xamputation was properly designed, this mayusua lly be avoided.

The degree by which the fina l prognosis ofthe sho rt-rooted central incisor will be com­promised depend s largely on how much rootremains after the amputation has been per­formed . The site of the amputation is entirelydepend ent on the location of the dil acerat ion,and it eliminates a majority of that portion ofthe root, apical to it, tha t had developed afterthe traumatic episode. Thus the closer thedilaceration is to the coronal portion of theroot, the shor ter will be the fina l roo t length atthe completion of trea tme nt and the poorer itsprog nosis.

Crown dilacerat ion

Dilaceration may also occur in the crown por­tion of the tooth, as has been ind icated earli er.In this eventuality. the tooth itself Illay not beso seriously d isplaced labially. When thecrown is surgically exposed. an attachment isbest placed on the labial surface, which isalmost certainly accessible. In this way, thecontinued downwards-di rected or thodontictraction will bring the root portion of thetooth from its mo re pal atally d isplaced loca­tion, close to its norma l position and its longaxis within normal limits. This will be due tothe lingual tip pi ng effect of the attac hment onthe lab ial surface. The too th will erup t withthe more incisal sec tion of its crown lab iallytipped and the post-traumatic section in a nacceptable angulation.

Res torative treatment is indica ted aftergrind ing off that po rtion of the crown that

73

74

represents the p re-tra uma dental de velop­menta l portion . The fut u re o f the too th willthen be founded on the majority portion ofthe tooth. which developed su bsequent to thetraumatic episode. Roo t canal treatment ma ybe required. and the ideal contour of the toothrestored us ing a crown and co re res toration.Rarelv, the d ilaceration site may be found tobe wry incisally pla ced, in which case a mo remodest compos ite material res torat ion maybe used , with vita lity main ta ined . In eitherC,lSC , the initial crown reconstru ction that isplaced sho uld be ma d e in ,1 line con tinuouswit h the long ax is of the root portion and anor thod ontic bracket bond ed to its appropria temid-lab ial position, read y for finishi ng . Fina lroot alignment, in both the labio-lingual andmesio-distal plan es, is then achieved in theusual manner for the particular ap pliance sys­tem bein g used .

Dilaceration of the coronal third of the root

The critical portion of the too th for the d ilac­or..ation to occu r is the coronal part of the root,

THE ORTHODONTIC TREATMENTOF IMPACTEDTEETH

close to the ccmcn to-cnamcl junc tion. In thissitua tion. the prognosis of the aligned too th isextremely poor, since the major ity o f its roo t,that rela ting to the post-trauma period ofdevelopment, \\;11 need to be amputated d ur­ing the procedure. leaving the too th wi th anon-viable coronal remnant of the root. Sucha tooth will need to be extracted . Nevertheless,it will be necessary to reopen the space in thedenta l a rch for some form of artificial replace­ment. Accord ing ly and reg ..ardlcs s of theprognosis, the sa me preparatory or thodonticp rocedu re is still advisable.

A modified John son' s twin-wire a rch ma ybe p laced and space opened up as accuratelyas possible, to provide exactly the rightamou nt, by compari ng it with its eruptedantimere. At this po in t, the dilnccrated too this exposed, an d. if its condition is confir medas ho peless, it may be extracted, bu t not dis­card ed! Instead , its contorted TOot is carefullysevered from the perfectly shaped CTOwn witha high-speed d iamond bur, and the pulpchamber cleaned and filled with a compositefilling material. The newly p repared natu ral

(., (hI

Hg ure 5.12

Tangontia l \'io>w~ of tho> com pleted alignment oi a dil aceratcd tWlh with mo' ca n al filling (,1) prior to and (b) afte rapkectotny an d rerrograd e dllldl~m iill in~. (Courtesy of Dr I Hl'linK& Dr \ 1 \1" r.lgJ

MAXILLARY CENTRALINCI$QR$

1.1

figure 5.13

Ib)

,•" ~ , ..

,:'=.. ,~': ........ 11II! . ', ' .

\' . ."

\ I ' ( ·l l ; · '1'1: r~ l i ~.l · · ' \

:, ~'

75

t,,) I'm :i,,'ly measured re"'0l-.,.,nin~ of tIll' ~Pi\","' is performed . using a removable appliance. (hI The prepa red crown uf thedilaccratc n 'ntrJI incisor, shown in Fig. 5A, is bonded between thc e tch...d inte rproximal surfaces of thl." adjacentteeth.

crown may then be bonded to the two adja­cent teeth. to act as its own space main taine r(Becker ct al. 1976), until a mo re s atisfactorvpe rmanen t replacemen t may be made, which,in view of the patient' s age, may not be forsevera l yea rs (Fig. 5.13).

Alterna tively, and provided that th e apicalpo rtion of the roo t is substa ntial, it may bead va ntageous to treat it in the manner of acro wn dilaceration, To achieve thi s, it will bencccss arv to remove the CTOwn of the too th atthe time' of surgical exposure and to pe rforman im mediate root cana l filling . A fixed ,threaded pos t is p repared and a sma ll hole isbo red th roug h its co ronal end. The post isthen firmly p laced. The roo t surface an dmuch of the co ron al pa r t of the post are cov­ered wit h a composite filling materia l, leavingthe tip of the post exposed , A stain less steelligatu re wire is passed through the preparedhole and lightly twisted in to ,1 pigtail with thehelp of ar tery forceps. In the absence of theacu tely angled crown portion, the remainderof the too th presen ts a less complica tedimpaction, whose resolu tion is s traightfor­wa rd .

The prepared too th is erupted into themouth unti l th e post an d the res tora tion cov­ering the roo t su rface become apparen t at thegingiva l level. The o rienta tion of the roo t ofthe tooth is then reassessed by palpation andby taking new ra d iographs - ,1 pe riapical for

the mesio-d ista l inclination and a tangl'llti alfor the bucca- lingual rela tionship . The latterview will bt> con siderably easie r to d iscernthan before, since the roo t 'canal filling will actas an excellent rad io-opaqu e marker .

The patient is no w referred for a ny neres­sary and appropriate muco-g tngiva l surge ryby a competent pe riodontist followed by theconstruc tion of a good q uality temporaryacryli c crown, wh ich is pla ced over the exist­ing po st. A general dentist or a specialistpro sthodontist is familia r with the need for'correcting' an abnormal root orien ta tion byplacing the artificial crown in line with thecrowns of the ad jacent teeth, regard less of theroot axis. This may be a sens ible comp romisein the mo re mino r non-impacted displa ce­ment cases, since orthod on tic ro ot movementmav then be avoided , However, in dil acera­tion cases, considerable root movement isneeded, and this is most su itably per formedwith the existing or thodontic applian ce. Forthis to be mad e pos sible, the temp orarycrown m ust he p laced at an angulation appro­pria te to the rece ntly confirmed long-axis or i­en tation of the roo t. Th e desired orientationof th is intended reco nstruction of the cro wnof the too th will not be in line with its neigh­bours, and this is not always an ea sy mes s ageto convey to the pros thod ont ist! Once thetem po rary art ificial restoration is in pla ce, abracket is placed in the usual manner. Crown

76

alignment and roo t torq ue an d uprighting arethen u ndertaken.

It may be seen that the po in t beyond whicha root amputa tion should be avoided is whenless th an one-th ird of the roo t will remainafter treatment. Cro wn amputa tion may beused as a viable altern at ive up to that point,but it must be remembered that the remain­ing root portion, which may be as little asone-ha lf to two-th irds its orig inal leng th, willbe narrower in bo th mes io-dista l and bucco­lingual d imen sion s, which will make theplacement of a satisfactory crown more d itfi­cu lt to achieve.

It is emphasized that , once the space in thearch has been gained and the tim e has comefor surgical exposure, accurate diagnosis ofthe exact location of the dilaceratio n is criticalif a valid decision is to be made. As pointedou t earlier, this is not always possible fromthe radi ographs, owing to the su perimposi­tion of other unerupted teet h an d neighbour ­ing roots on the tangential view. Theperiapical view can contribu te nothin g in thisrespect.

If it is still impossible to locate the dilacera­tion then an attachment should be placed onthe lingual sid e of the tooth, as before, an dthe initial traction applied to bring the crowno f the tooth occlusally. A decision to ampu­tate the roo t portion of the tooth must , in an ycase, be d elayed until the root is palpable,bu lging into the labial su lcus. At each su bse ­quent visit, the sulcus should be carefullychecked, an d any palpable change in thepositi on of th e roo t apex in this d irectionshould be compared with the downwardprogress and eruption s ta tus of the cro wnand its angula tion. Prow ess rad iographsshould be taken at appropria te stag es, u ntilthe exac t location of the dila ceration maybe p inpointed or ot herwise clinically diag­nosed , par ticularly in relat ion to the longaxes of the two parts o f the too th. Oncethe accurate d iagnosis has been es tablished,a reassessmen t of the treatment approachshou ld be mad e to decide whether th e lineof treatment is indeed appropria te or whetherthe crown port ion should be amputatedand the direction of traction alte red accord ­ingly.

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

ACUTE TRAUMATIC INTRUSIVELUXATION

Following trau matic in trusive luxa tion, theaffected too th may re-erupt and may eventu ­ally retu rn to its original position (Shapira etal , 1986). In other cases, however, th e toothrema ins intruded and ma y require o rthodon­tic assistance to encou rag e re-cruption. Forthese cases, the emergency treatment andsome initial res torative procedures willalready have been carried out by the pae­d od ontist or the oral su rgeo n, and the patientwill not be in pa in at the time that orthod on ticassis tance is required .

For this tooth to ' take ' and be success ful,the d esired union of tooth to the su rround ingbone is by healing alone or by healing withsurface resorption. Accor ding to Andreasenand Andreasen (1994), healing w itho ut sur ­face res orp tion is probab ly not a po ssibil ity inthe clinica l situa tion, since it must be com­pleted totally without inju ry to the Inne rmos tlayer of the periodonta l ligament. However ,healing with surface resorption will leave thelu xated too th atta ched to th e socket with anormal periodontal liga ment and new cemen­tum. Such a tooth wi ll respond to orthodonticforces .

If, on the othe r hand, healing is by replace­ment resorp tion, there is a d irect unionbe tween the roo t and the su rround ing bone.Repair will be counted as successful, but thetoo th will then never be amenable to ortho­dontic forces . The too th may so metimesregain a normal attachmen t (a tran sientrep lacemen t resorp tion), altho ugh this is byno means certain, and it is probably morelike ly that areas of ankylosis will occur overthe root surface an d th e too th will thenremain in trud ed permanently . The too th, as itstands, is then of no va lue to the dentition,nor is it us eful as a fou nda tion for lastingp rosthodontic res toration . Under these cond i­tions, its extraction will be indica ted .

O rthod ontic in tervention a t the appropriatetime ma y offer the only viab le treatm entoption tha t, together with certa in rela tivelyminor res torative p rocedures, may p roducean excellent result with a fai r p rognosis. If thetoo th is still complete ly su bgingival th en the

MAXILLARY CENTRAL INCISORS

", 'd

(dl

(,I

77

Figure 5.14

(,1) Acute intrusion of ,1 m,nill,l ry ldl and crown fracture of the ma xillary rig ht central incisors. (bl The tangentia l radi­ograph shows intrusive and buccal dis placement. (c) At ]4 days post-trauma, a but ton at tachment is bond ed to theintruded incisor. The labia l arch is activa ted to ex trude the too th and the patien t is instructed in accu ra te plac~'ffien t"lOd

can'. (d,c) The tooth hil" re-erupted . Bo th central incisors have had root cana l trea tment an d crown restoration.(Courtesy " f Dr B I'en 'tz.)

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH78 _ _ _ ______------'=...:.....c--=..::..:.------'=---=---=-----------=--==__=:.._

labia l soft tissue will need to be superiorlyrepositioned, un til 2 mm of the incisa l edge ofthe too th is revealed. Light extrusive forcemust be applied after the lime that the perio­dontal fibres have begun to re-unite and inthe earlier stages of the organ ization of theblood dot, but before the laying d own ofbone, i.e. 10-28 days pos t-trau ma .

Special ca re must be exercised when us ingfixed applia nces in this situa tion (Andreasenand Andrea sen, 1994). Firs t, with or without

the use of orthodontic brackets, some kind ofresis tent fram ework need s to be bo nded tothe adjacent teeth, which act as a multip leanchor unit fro m which force would beapplied to the intruded too th . Th is cou ld takethe form of a few brackets and an archwire,althoug h the composite bonding of wiredirectly to the labial enamel of these teethwould be more satisfactory from manypoints of view. Unfortunately, these teeththemselves will almost certainly have been

[a]

foJ Cd)

Fij;llre 5.15

(a.b) Front an d left "jews, showing pal atall y di splaced cen tra l incisor, I we-ek pos t-trauma. The crown red uctkm isclt'arly seen. k .dl Mod ified Johnso n's twin-arch applia nce in place . Buccal coil sp rings apply labia l tip pin)o\ fur.....• on the"'inglt' 0.018" ar chwire, wh ic-h ensas'''' the br ae-let of the d isplaced too th. (e,O A torqueng auxiliary is laced down to themain archwire and 1iC\l back to the molar tu bes. (g-il 12 mo nths after co mpletion of treatment: fron t an d left views ofthl.' occlusjon and a close- up view of the ma xilla ry cen tra l incisor teeth . (j,kl Tan genlial "nd po..'l'i.1pical p retrea tmen t\; ew ". (I,m) Tange ntia l and pe riapical views 4 weeks late r. (nl Periapical view at 12 months shows obli tera ting vita lpulp.

MAXILLARY CENTRAL INC ISORS

(e)

(8)

(j)

(h )

(figure 5.15 ...>U li"'....n

79

THE ORTHODONT IC TREATMENT OF IMPACTED TEETH80 ___ _ _ _ _ _ _ _ _ ____=-c- _=_~

(Figure 5.15 continued )

(j)

,k)

(m)

111 (n)

MAXILLA RY CENTRAL INCISORS

trau matized at the time of the accident, an dusing them in th is manner ma y lead to furth erd am age, even at th e light force levelsinvolved. Second ly, if the intended extrusionis performed more tha n 2 mont hs ,post­trauma, ankylosis may have affected the tar­get tooth (And reasen and Andreasen, 1994).Active extrusive forces generated by the appli­ance will then be of no avail. Instead , the reac­tive forces will be absorbed by the ad jacen tanchor teeth, and these will become intruded .

Simple remo vable appliances (Fig . 5.14) aremos t su itable, since they need apply no forceto the ad jacen t tee th, which may also havebeen damaged in the traumatic expe rience(Peretz et al, 1982; Member. 1994). A smallbutton atta ch ment is bond ed on the labialside of the too th and the lab ial bow of theremovable ap pliance is d ivided at the mid lineand activated vertically downward s againstthe button. Treatmen t generally proceedsrapid ly, with the too th appearing in themo u th and at the level of its neighbou rswith in a few weeks, dependi ng on theamo unt of extrusion requ ired . Once the too therupts, root canal therapy is usually ru..ceded.and a pennanent restora tion may be placed ,followed by a short pe riod of retent ion .

Intrud ed teeth whose root development iscompleted are generally scheduled for roo ttrea tme nt in the first week after the traumaticincid en t. Under id eal circu ms tances, ortho­don tic trea tme n t o f endod ontically trea tedteeth is not normally advised unt il they havebeen followe d up for several months anduntil the re is some rad iogr aph ic evid ence ofrepair. However, following in trusive trauma,the possibili ty of th e occu rrence o f ankylosis(repla cem ent resorption ) is significan t, andwill be evid ent wi thin two mont hs. Th us theexceptional circumstances d icta te th at theor thodontic extrusion of these tee th mus tbegin , at the latest, six weeks or so after thetrauma tic episode, although the IG-28·d aytime frame is to be preferred . The risk of fail­ure of extrusion d ue to repl acement resorp­tion is high and absolute, which is whytreatment sho uld begin within this time. Therisk of an orthodontically ind uced need forroot trea tmen t is much lower and of lessthe rapeutic significance.

Once the too th has been brough t into align­me nt, it may be-retained and splinted to itsimmed iate neighbours, using a short lengthof multistranded wire, which is bonded to thelab ial surface of the three teeth , for a fewmonths on ly. It is important not to cover thewire completely w ith composite materia l, bu tto p lace a small blob of composite materialacross the wire over eac h too th and to leavebroad areas of exposed and flexible wi re.Rigid bond ing for long period s is contrain di­cated , since it seems to lead to a grea ter inci­dence of pulp necros is and p ulp obliteration(Andreasen and Vcstcrgaard Ped ersen , 1985;Rock and Grund y, 1981). However, the mu lti­stranded wire spli nt allows a d egr ee of mo ve­men t, which is similar in extent to that !ieen inphysiological mobility (Becker, 1987; Beckerand Goultschln. 1984; Zachr isson. 1977; Dahland Zachn sson. 1.991), and thus may prob­ably be safely used for conside rably longer.Ap propria te res tora tion may be undertakenbe fore or after this splinting has been com­p leted .

A child may sustain a severe blow to thepremaxillary area , d isplacing a maxillary cen­tral incisor in such a ' vay th at the crown istipped inwards and the root protrud esth rough the alveolar bone. The pa tient isunable to close the teeth together, owing toprematurity on the d isplaced too th. In theheat of the momen t and lack ing su itabled irection , the paren ts of a child do not alwaysattend the appropri ate clinic or the mostknowled geable d ental practitione r.

The emergency treatment ind icated for thiscase is to ma nip ula te the too th to its originalsite, under 10C,ll an aest hetic and to sp lint it inp lace. The pa tien t shown in Fig. 5.15 wa strea ted by grind ing the incisor to red uce theocclusal in terferen ce, and wa s given ,1 bitep late to disa rticu late the teeth! When the par­en t was finally referred else vv-here, seve ralda ys had elapsed and manipu lative red uctionof the d isplacement wa s no longer approp ri­ate. Orthod ontic trea tm ent wa s p resc ribed toresi te the too th by applying labial tip ping andthen palatal root torque. Since th is involvedits being moved thro ugh freshly organizingblood clot, the trcarnent proceed ed with greatspeed . The too th maintained its vitality, as

81

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH82 _______ _ _ _ "-'---.....::..::..::--"-.:...:..=.:..:=:c='--.:.:.:~

evidenced by positive pulp tes ting and bypulp oblite ration . Finally, the grou nd-downcrown was improved with a compositerestoration, and follow-up periapical radio­gra phy will determine whether root resorp­tion occurs and if appropriate root canaltherapy will be needed .

REFERENCES

Andreasen 10 , Andreasen FM (1994) Textbookand Color Atlas of Traumatic Injuries to theTeeth. Munksgaard, Copen hagen .

And reasen RM, v crstergaard Pedersen B(1985) Prognos is of luxa ted pe rmanent teeth ­the developmen t of pu lp nec rosis. Ended DentTraunmtotv: 207-20.

Battagc l 1 (1985) The case for early assess­ment : 2: trea tmen t with specialis t support.Denial Update 12: 293-8.

Becker A (1987) Periodontal sp lin ting withmultistrand wire follow ing orthod onticrealignment of migrated teeth: report of 38cases. l1/tl J Adl/lt Ort}wtl OrtllOX" 511rg 2:99-109.

Becker A, Go ul tschin J (1984) The mult istrandretai ner and splint. Am I OrtJw(/ 85; 47()-4.

Becker A, Stern N, Zelcer Z (1976) Utilizationof a dil acerat ed incisor too th as its own spacemai nt ainer. I Dellt 4 : 263-4.

Becker A, Koh avi D, Zilbcrman Y (1983)Per iodon tal status following till' alignment ofpal atally impacted cani ne teeth. Am I Orthod84, 332-6 .

Bodcuham RS (1967) The treatme nt and prog­nosis of un erupted maxillary incisors, associ­ated with the p rcsc nce of supern umeraryteet h. Br oo«1 123: 173-7.

Boyer DB, Williams VD, Tha yer KE (]993)Analysis of debond ra tes of resin-bond edprost heses. I Dellt Res 72:12~.

Brin I, Zilbcrman Y, AZ,lZ B (1982) Theunerupted maxilla ry central incisor; review of

its etiology and treatment. I Dent CI/i1d 43:352-6.

Brook AH ( 974) Den tal anomalies ofnumber, form and size: their prevalence inBritish schoolc hild ren. I lilt AS${ J(' Dent Child 5:37-53.

Dahl EH, Zachrisson B (199t) Long-termexperi ence with direct-bonded ling ua l retain­ers.1 Cun Orthad 25: 619-30.

Day Re B (1964) Supernumerary tee th in theprema xillary region . Br Dent 1 11 ~ : 304-8.

Di Blase DD (971) The effects of variations intoo th mo rp ho logy and position on eruption.DCIl I Pmct o-« Rec 22: 95- 1OR.

Gard iner jII (961) Supernumerary teet h.Dellt Pract Denl Rec 12: 63- 73.

Hotz R (1961) Orthodontia in EI'avdml Practice.Huber, Berne. . .

Ho usto n WJB, Tu lley WJ ( 986) A Textbotlk ofOrthodontics, pp 126-31. Wright, Bristol.

Howa rd RD (]967) The unerupted incisor.Om t Prod Dm t Rec 17: 332-42.

Howe GL (971) Millor Oral Surgery, 2nd edn,pp 135-7. Wrigh t, Bristol.

Ingber sj ( 974) Forced. eru p tion. Part I. Amethod of trea ting iso lated one and two wallinf rabony osseous defects - rationa le a nd caserepo rt. I Period 45: 199-206.

Ing ber SJ ( 976) Forced eruption. Part II. Amethod of treating non-rest orable teeth ­periodon tal and restor ative considera tions. Iflaiod 47: 203-16.

Johnso n JE (1 934) A new or th odonti c rnecha­nisrn : the twi n wire alignmen t appliance.In/em il ! I Ortncd 20: 946-63.

Kettle MA (1958) Unerupted uppl'r incisors.Tmlls Eur Unhad Soc 34: 388-95.

Kohavi 0 , Becker A, Zilbcrma n Y (1984)Surgical exposure, orthodontic' mov ementand final too th position as factors in peri­odontal breakdown of trea ted pala tallyimpac ts..'CI. canines. Am i Drthod 85: 72- 7.

Mambcr EK ( 994) Treatment of intruded

MAXILLARY CENTRAL INCISORS

perman ent incisors: a multidi sciplinaryapproach. Eudod DCllt Tral/lllalo/ 10: 98-104.

Melsen B (1 986) Tissue reaction followinga pplication of ext rusive and intru sive forcesto tee th in ad ult monkeys. Am I Orthod 89:469- 75.

Mills JRE (1 987) Prillciples and Practice ofOrtJlll(ftlllticS. 2nd ron. Churchill Livingstone,Edinb urgh.

Mitchell L, Bennett TG (1992) Supern umera ryteeth causing delayed eruption - a retrospec­tive study. Br I Orthod 19: 41--6.

Munns 0 (1981) Unerupted incisors. Br IOrO/(/(1 8: 39-4 2.

Pere tz B, Becker A, Chosa k A (1982) Thereposition ing of a traum atically-in trudedmature rooted permanent incisor with arem ovable appliance. J Pedodont 6: 343-54.

Rock WP, Grundy MC (1981> The effect ofluxation and subluxation upon the prognosisof traumatized inciso r teeth . I Dellt 9: 224-30.

Sewa rd GR (1 968) Radio logy in general den­tal practice. IX - Unerupted maxillarycanines . cen tral incisors and supe rnumer­aries. Br Dmt 1 115: 85- 91.

Shapira J. Regev L, Liebfeld H (1 986) Re­eruption of completely int ruded immaturepermanent incisors. Eudoll Dent Traumatot 2:11 ~16.

Shepa rd ES (1 960 Technique and Treatmentwith the Twill- Wire Appliallce Mosby, St Louis.

Stem N , Bec ker A (1980) Forced eruption: bio­logical and clinica l conside r..arions . I OralRelmbil 7: 395-402.

Stewart OJ (1978) Dilacera te uneru pted maxil­la ry cen tral inciso rs. Br Denl I 145; 229-33 .

Tay F, Pang A, Yuen 5 (1984) Une ru ptedmaxillary an terior supern umerary teeth:repo rt of 204 cescs. J Dent Chifd 51: 289-94.

Witsenberg B, Boerin g G (J98J) Eruption ofimpacted permanent upper incisor teeth afterremoval of supern ume rary teeth . J Oral SI/rg10: 423-3] .

Zachrisson BU (]977) Clinical experi ence wit hdirect-bonded orthodontic retainers. Am IOrthod 71: 44o-B .

Zilberman Y, Malm n M. Shteyc r A (J992)Assessment of 100 children in Jerusalem withsupernumerary teeth in the premaxillaryreg ion. J DCllt Child 59: 44- 7.

83

6 PALATALLY IMPACTED CANINES

CONTENTS • Prevalence • Aetiology • Complication s of the untreated Impactedcani ne • Diagn osis • Treatm ent t iming • General pr incip les of mechanotherapy• The nee d for classif ica tion of the palatal cani ne • A cl assif ication o f palatall y impactedcani nes

PREVALENCE

In any population, the preva lence of palatallyimpacted maxillary canines is low, but itsee ms to have a variable d istribution withregard to ethnic orig in. The lowest frequencyreported in the lite rature relat es to theJapanese (fakahama an d Aiyama, 1982),where the anomaly occurred in onl y 0.27% ofthe sam ple population. Some very ear ly stud­ies by Cramer (1929) am ong wh ite Ame ricansand Mead (1930) in an und efined sa mplefound 1.4% and 1.57% respectively. A studyof a lar ge series of full mout h denta l rad io­graphs among pa tient s in the USA revealed afigure of 0.92')1" (Dachi and Howell, 1961),while Brin ct al (1986), in a study of an Israelipopu lation, found a level of 1.5'X,. The highestfigu re for the anomaly found in the morerecent su rveys, 1.8%, has been rep orted in thestud y by Thi lander and Jacobson (1968), of anIcelandic popu lation.

Montelius (1932) was the first to ind icate ad ifference between Caucasian and Orientalpopulations, altho ugh he found a frequency of1.7% for Chinese and 5.9% for Caucas ians.However, since he did not d istingu ishbetween buccal and palatal impaction in his

study, little usefu l information may begleaned from these figures in the immedi atecontext. More recently, the work of Oliver ct al(1989) has indirectly indicated that Asiansmay suffer from buccally impacted caninesmore frequently than from palatal canines .While th is appears to be suppo rted by variouscase reports that haw appeared in the litera­ture from the Far East, no definitive study ha sbeen undertaken to investigate this possibility.

A strong prevalence of impacted canines isfound among females, with a ratio of 2.3 : 1(Dachi and Ho well, 1961) in the above­mentioned group of Am erican pa tients, 2.5 : 1(Becker et al. 1981) in an Israeli orthodonticgroup, and 3: I in both a Welsh or thodonticgroup (Oliver ct al, 1989) an d in a US or tho­dontic sam ple (joh nston, 1969).

However, some con fus ion exists withregard tothese figures, since a random Israelipopulation study (Brln et al, 1986) ha s shownan approximately eq ual male-fem ale occur­rence of the an omaly. Furthermore, O liver ctal (1989) have ind icated tha t, although ahigher female incidence was present in theirstudy of Welsh patients, this reflected thetrend for more females to seek orthodontictreatment in the UK.

THE QRTHOOONTIC TREATMENT OF IMPACTED TEETH86------------------ - ---

(, )

Figure 6.1

(a) An terio r occlusal view sho ws an im pacted canine. anodomo me and a missing la l~'ral incisor. (b) Periapical\'iew of impacted canine and first premolar associa tedwith en odoruome and over-retained decldcous firstmolar.

(b )

If we are to ass ume that the motivation forth is is that girls are more concerned w ithimproving their appearance then the diagno­sis of an impacted maxillary canine, given thepresence of an over-retained . deciduouscanine, is not usually the cause for the patientpresenting for orthodontic treatment. Ap­pearance is rarely marred by this, since thereis a complete and uninterrupted di splay ofteeth, and any abnormalities are usua lly notd isfiguring. Motiva tion for treatmen t m aytherefo re rather depend on the ability andpersuasiveness of a pa rticular practitioner inpointing ou t the po tential haza rds of non­treatmen t. There may be no basis to expectthat this wo uld convince more femalepa tien ts than males to accept trea tment.

tal origin (Fig. 6.1) will undoubted ly prod uceabnormal position ing of an uneru pted pe rma­nent maxillary canine, but they a re compara­tively rare in the canine area . The fact that themajority of impacted canines occur in theirabse nce compels us to look elsew here for themain causes of impaction.

To explain the mecha nism of palatal dis­placement of the maxilla ry canine, some ofthe hypo theses that have been put forwardhave been int imately invo lved with aberra­tion in the normal process by which the max­illary an terior tee th erupt. For this rea"011, anund erstanding of norm al development in thisarea is important

Normal development

AETIOLOGY

There is no single cause of the palatal dis­placement of the maxillary canine tooth.Space-occu pying, extraneous ent ities of den-

In the midd le pe riod of the de ciduous den ti­tion, a per iapica l rad iogra ph of the premaxil­lary region will show thc fully compl etedde ciduous incisor roots. It will show the ove r­lap ping shadows of the permanent centra l

PALATAllY IMPACTED CANINES

an d lateral incisors, more or less in the samehorizon tal p lane (Fig. 6.2.1 ) as the ap ical halfof the root s of the deciduous inciso rs, withthe canines being sited higher up_The over­lap of the pe rmanent teeth crowns is due tothe fact that these relatively wide pe rmanenttee th arc all contained in a narrow area and.

,.)

at this time, a re in itia lly located palatally inthe alveolus. The developmental position ofthe lateral incisors is palata l with relation toboth the central incisors and to the pe rmanen tcanines. For these reasons, the peri apical viewdescri bed above gives the appearance ofsevere crowding.

(b )

87

, -

Figure 6.2

(a) A periapica l view of maxillary pe rmam'nt incisor, ,Itage 3 years . Notl' thc J egl"l-'l' of overla p of unerupted !-"-'r­mancnt cen tra! and lateral incisors. (b) Thc sa me p,llil'n lat 5 years . The permanent cent ral incisors ha ve migratedinferiorly and labia lly relative to thl· la lerJI inci".,r.;. Nol l'the reduced Jl'~n.'l' of inci sor o,-erl.lp_ (e) Th,' u 'nl.alincisors all.' ,'rupling .It .lg" 6.5 years. N ote how the lat­e ral incisors MW m igr.lll-d labially into the arch to clirm­nate the O\·".I.lp evrn pl" lely. (Co urtesy of Dr B l'e rMz.)

,<)

88

During the early erup tive movements ofthe central incisors, a progressive resorptionof the roo ts of the d ecid uous incisors occurs.The pe rmanent inciso rs migrate slowly acrossfrom the palatal side of the arch to the labial.as they proceed in their downward path, un tilthe teeth erupt into a more labial perimeterthan wa s defined by the decid uous incisorteeth before their shedd ing. Du ring th isp rocess, the wide crown po rt ion of the cent ralincisors will have moved down ward s andlabially (Fig. 6.2b). As thi s occu rs, the pro­gress ively narrower eEJ area and then rootportion of the central incisor come to liemesial 10 the unerupted lateral incisorcrowns. This leads to the fairly rapid prov i­sion of space at this level in the alveo lus(Friel, 19-19). The lateral incisor m igrates labi­ally in to this a rea as it begins its downwarderup tion pa th. Additiona lly, the downwarderup tion moveme n t d istan ces it from the pe r·manent canine crown, p rovid ing mo re spacefor it to move lab ially, following closelybeh ind the central inci sor.

With the er u ption of the cen tral incisors,the later al incisor crowns move from a lingua lrelation sh ip into a d irect d istal relationshipwit h the central incisor roots, initi ally at ah igher level (Fig. 6.2c). As this occurs, thep resence of the lateral incisor crowns dis­p laces the developing ap ical area of the cen­tral incisors towards one another, since theseare at the same level, within the alveolarbone. With the cent ral incisor apices he ldtogethe r in this way, the crowns of these tee thare flared d is tally . A d evelop men tally norma lmed ian diastema is thus p roduced, wh ich hasbeen termed the ' ugly duckling' (Broad bent,194 1).

A year or so later, the lateral incisors willha ve de scen ded along the distal side of thecentral inciso r roots, to release their 'hold' onthe na rrowed in ter-apical w idth o f the centralincisor roo ts, allowing the roo ts to d rift apa rt.The lateral incisors continue to move in feri­orly along their eruptive path, progressivelyreducing their constricting influence on thecent ral incisor roots u nti l they reach the distalside of the nec ks of the central incisor crowns.At th is po int , their p resence and continueddownward migration serves to provid e a

THEORTHODONTIC TREATMENT OF IMPACTED TEETH

mesially d irec ted force to the crowns of theseteeth, moving them towards one another andpartially closing off the median diastema. Thelong axes of the cent ral incisor teeth will alsohave changed, wit h the roo ts becoming mo repara llel. The lateral incisor long axes, how­ever, are relatively flared in the coro nal d irec­tion, wi th their root apices close to those o fthe cen tral incis ors.

A periapical view of the area at this timewill show the uneru pted permanent can inecrowns, of eac h side, poi nt ing mesiall ytoward s the lateral incisor apical area. Theyappea r to be the containing influence thatcauses the ap ical convergence of the incisorroots and the reason that the med iandiastema has not completely closed. Sub­sequent follow-up radiographs of the areaw ill show the permanent can ine alte ring itsrelationsh ip as it moves d ownward s alongthe distal s ide of the roo t o f the late ral incisor,uprighting the long axis of that tooth . Thecanine's own long ax is becomes mo re verticalas it p rog resses an d as the root of the d ecidu­ous can ine becom es resorbed. With the shed­di ng of the deciduous canine, it finally eru p tswit h a sligh t mesial inclination, taking u p itsp lace in the arch by moving the crow ns of theincisors towards the mid line, to close off thed iastema completely (Becker, 1978). As allth is occurs, the long axes of the incisor teethchange from being apically convergent tobecome more parallel and even slightly diver­gent.

Th roughou t the period of its downwa rdp rog ress, the pe rma nent canine is conspicu ­ous ly palpab le on the buccal side of the alveo­lar rid ge, from as early as 2 or 3 yea rs prior toits norm al eruption, which no rmally occurs atthe age of 11- 13 years.

Theories regarding the causes of palataldisp lacement

Long path of eruption

From the early da ys of Broad ben t, in the19405, the most com mon reason g iven forpalatal d isplacemen t of the pe rmanent ma xil-

PALATALLY IMPACTED CANINES

lary canine was the fact tha t it ha d a long andtortuous erup tion path, beg inn ing close to thefloor of the orbit . It was cons idered that thistooth had much further to travel before iterupted into the mouth an d that it thereforehad a greater chance of ' losing its way' . Thishas been standard teac hing for many years.

Crowd ing

Hitchin (1956) considered that crowding ofthe dentition was the reason for this condi­tion , althou gh he offered no evidence to sup­po rt his contention.

In general, crowding of the dentitionresults in the exaggerated displacement of atooth from its developmental position in thearch. The developmental position of the max ­illary lateral incisor is lingual to the line of thearch, as we have already described above.Thu s, when crowding affects the earl y mixeddentition, there will be insufficient space forthe lateral incisor to migrate labially betweenthe root of the cen tral incisor and the dec idu­ous canine teeth, which is the manner inwhich it normally comes into the dental arch.It therefore cont inues to develop downwards,bu t in a lingual position, and erupts lingual tothe adjacent tee th.

A pa rallel env ironment is created when asecond decidu ous maxillary molar is ex­tracted before its du e time, and the first per ­manent molar drifts mesially into theavailable space. Similarly to the lateralincisor, the developing second premolardevelops palata lly to the line of the arch, an dits con tinued development and eruptive pathwill be in an exaggerated pa latal d irect ion, inmuch the same way .

We have po inted out above that the normaleruption path of the permanen t canine is buc­cal to the line of the arch, and we also kno wthat the latera l inciso r and first premolar, theteeth immediately ad jacent to the canine,erupt before the can ine. Thus, in the presen ceof crowding. there will be reduced space inthe arch in the can ine area, and the closeproximity of these ad jacen t teeth will preventthe canine from moving into the arch . Thevertical development of the maxillary perma­nen t canine will therefore be accompanied byits buccal d isplacement, to give the typ icalpicture seen in the class 1 crowded case (Fig.6.3). Whether the tooth eventually erupts orrema ins im pacted is irrelevant, altho ugh buc­cal impaction is most unusual.

It is therefore qu ite clear that the cause ofth is type of d isplacement of the can ine is

89

Figu re 6.3

Bu( (ally displaced maxilla ry canines due 10 acrowded arch.

THE ORTHODONTICTREATMENT OF IMPACTED TEETH9O ~_=____=____= =_=::c

completely different from that involved withpalatal displacement. The two conditions aredifferent entities . They shou ld never be con­fused, no r shou ld they be lumped toge ther to[ann an experimenta l group for clin icalresearch, as if to offer a homogeneous sampleo f impacted teeth . For the purposes of study,it is far more logical to combine all palata llydisplaced canines. whethe r they are un erup4ted or erupted, since they share a com monaetiology, although their clini cal p resentationIllay be d ifferent.

In a series of more recent clin ical researchstudies, Jacoby (1983), Becker (19&1 ) and Brioet .11 (1986 ) have pointed ou t that the likeli­hood of palatal displacement is muchreduced where crowding is p resent. On thecontrary, they have shown it to be a far moreprevalent occurrence when there is excessi vespace in the denta l arch.

Non-resorption of the root of the deciduouscanine

Lappin (1951) cons idered that it was the fail­ure of the root of the deciduous canine toresorb that caus ed a pa latal deflection of theeru ption pa th of the pe rman ent canine, lead ­ing to its im paction.

Here, too, one may d raw a parallel withother teeth. In cases where .1 second decidu­ous molar is over-retained, owing to the pres­ence of a malposed tooth germ, one may oftensec on the pe riapical or panoramic radio­grap h th at on e of the roots has totallyreso rbed , while the second roo l is on ly par­tially so. The lon g: spi cu le of unresorbcd rootthat may be prese nt re ta ins the too th againstnatur al shed d ing, while the fu lly deve lopedand unerupted second premol ar is situa tedimmediately be nea th the crovvn of the decid­uous tooth; in the area previously occupiedby the resorbed portion o f the roo ts.

Fro m this ty pe of clinical evi de nce, which isseen so widely and freq uently in practice, it isgenerally con sidered that the presence andad vancing eruption of the permanent toothprovides the s timu lus for the reso rption, anda po rtion of root distant from the uneruptedpermane n t too th may be unaffected by thisp roce ss. On the basis o f this, Lap pi n' s view

would appear to be ' pu tting the cart be forethe horse'.

Nevertheless , and in su pport of his argu 4

ment, subsequent st udies (Howa rd , 1967;Ericson and Kurol 1988c; Lindauer et al, 1992;Power and Short, 1993) have shown the spon­taneous eruption o f p reviously impa ctedcanines in many cases, followi ng the ext rac­tion of deciduous can ine s. This will be d is­cussed at length later in this chap te r, underthe head ing 'Preventive treatme nt and itstimi ng' .

Trauma

In a recent clin ical repor t Brin et al (1993b)have illu strated how trauma, which leads to acessation in the develo pment of a la teralincisor roo t, may be associated with palatalcanine impaction . They expl ain th is byassu ming that

(a ) the traum atic episod e may ha ve caus edmovement of the lateral incisor, or

(b) by cond uc tion, movement of the unerup­ted canine itse lf, or

(c) in terms of the guidan ce theo ry, this isdue to the shortness of the la teral incisorroot, whose develop me nt ceased as theres ul t of the trau ma.

A fu rthe r alt ernative cou ld place the blame onthe possible p resence of chronic irr ita tion orresid ual infection a round the ape x of a non­vita l decid iou s can ine too th (Fig. 6.4), wh ichmay equa lly have p rod uced the dc fle..-ctedpath o f eru ption, as po in ted ou t by Fca rneand Lee (1988).

The gu idance theory

Miller (1963) an d Bass (1967) reported thatthere appeared to be an u nusua lly highpreva lence of congen ita lly m issing late ralincisors associa ted wit h palatally impactedcan ine teeth. They theorized th at, u nder thesecir cumstances, the permane n t ca nine lacksthe gu idance normally afforded by the di st alaspect of the lateral inciso r roo t. As po intedout earlier, in relat ion to norma l d evelop­ment, the canine initially has a strong mesialdevelopmental pa th, which alters ea rly on ,

PALATALLY IMPACTED CANINES

(.1)

Figure 6,4

(b)

91

(.1, b) PL'ri,lpicil1 views of twu impacted canines, each associ ated with a non -vita l decid uous canine.

w ith the canine be ing guided d ownwards,apparently along the d istal aspect of the la t­eral incisor root. Thev concluded tha t, in theabsence of this guid ing influence, the canineconti nu es in its initial mesial an d palatal path.The too th then becomes impacted in thepalata l area, posterior to the cen tra l incisors,and fails to eru pt in its d ue time, if a t all.

Miller's concept was founded on informa­tion gleaned from the st udy of six such cases.He assumed that , since a peg-shaped or oth­erwise abnorm ally sma ll la tera l incisor dev el­ops it roo t of mo re or less normallength, sucha tooth wo ul d provide the requ ired guid ancefor the normal eruption of its ad jacen t canine.He therefore ration alized that these anom­alous teeth could not be an ae tiologic factor incanine im pac tion.

Follow ing the trea tmen t o f se ve ral h undredcases o f this type by the p resent author, a d if­ferent pa ttern of association seemed apparent.Palatal im paction of the maxilla ry canineap pea red to be intimately bound up with theoccurrence of anomalous lateral incisors an dless \v ith the congenitally missing teeth .

Fu rthermore, a stereotype of the maxillaryim pacted canine patient could be offered(Fig . 6.5), in which the patient is frequently a15-year-old female, with well-aligned andnormally rela ted dental arches, sligh t spacingand no real malocclu sion. Characteri stica lly,the tee th are small, the lateral incisors pa rticu ­larly so, the re may be miss ing teeth, d entaldeve lopment is la te and the patient's motiva­tion for trea tment is lovv,

A series of clinica l research stud ies fol­lowed, in which a sample of pa tients whowere su ccessfu lly treated for a pal atally J is­placed canine was s tudied. In the first study(Becker ct al. 1981), a wid e and hig hly s ign ifi­can t di screpancy in the num bers of no rmal,sma ll an d peg-sh aped lateral incisors ad jacentto an a ffected can ine was found , comparedwith the p ublished data for no rma l pop ula­tions. In the interes ts of accuracy, a randomstudy wa s later pe rformed by the sameresearch group (Brin et al, 1986) to qu an tifythe va riou s types of lateral incisors foundwithin the general population of the sa megeographic area, while using the same defini-

THE ORTHODONTICTREATMENT OF IMPACTEDTEETH92 _________ ----'---~__=_::..c____'___=___=___"__=__=~

Figure 6.5

Late developing d ...n tition showing sp acing, small pt'g ­shaped lateral incisors, teeth of poo r ana tom ica l contourand minor Clas s I malocclusion.

tiona o f anomaly. In the general popu lat ion,93'1" of all lateral incisor teeth were of normalshape and size, compared with only 52% inthe palatal canine sample. In the random pop·u lation sa mple, missing lateral incisors werefound in approximately 1% of the cases,which contras ted ma rked ly w ith the 5.5% ofth is anomaly among the' impacted ca ninecases, Of 5 times as frequentl y.

These results d early support the concept ofMiller and of Bass regardi ng the pa rt playedby th e lateral inc iso r as a guide in the normalerupti on of the perm anent can ine . Withoutthis gui dance, normal erup tion is com pro­mised fivefo ld.

Ho wever, Mille r's rationaliza tion regardingthe positive role of anomalous lateral incisorsappears very much misplaced. Sm all lateralincisors we re seen in only -1% o f the ra ndomsam ple. wh ile the palatal canine casesshowed this anomaly to be 8 times as fre­quen t (25%). Furthermo re, only 2°;', of thegenera l populati on had peg-sh aped incisors,while 17'1., (9 times the frequen cy) were seenamong the palatal cani ne cases. Similarresu lts have since bee n shown in confirms­to rv studies th ai have exam ined Welsh(Oliver et al, 1989) and west of Scotland(Mossey et al, 1994) samples.

Were small or peg-shaped lateral incisors tohave p laye d a positive role of any sort, as out­lined in the guidance theo ry, the n one wouldexpect figu res lower than 5.5%. Their pres­ence is shown here to offer mo re than merelya loss o f guid ance to the de veloping penna-

nen t can ine. The fact that the y increase thechance for im paction to almost twice tha t ofthe missing lateral suggests tha t an add i­tional, obstructive ro le is played by theseteeth.

In the first st udy (Becker et at 1981), ahypothes is was presen ted based on the factthat the anomalou s small and peg-shaped la t­eral inci so rs develop very much laler thanno rma l latera l incisors. While no figu res a reava ilable for the extent o f this delay, it see msclear from clinica l observation that it may beas much as 3 years - and this for teeth wh osecalcification normally begins at age 10-12mon ths!

If we arc now to relate this to the 'gu id ancetheory of im paction', we may postula te tha t atthe critical time that the permanen t can inerequires the gu id ance, the roo t of the an om ­alous lateral incisor is too rudimentari lydeveloped to p rovide it . Thus initi ally thesituation is pa rallel to that see n in congenitallateral inc isor absence. The result is tha tthe canine d eve lops mesially an d palat allyand usu ally in a downwards d irection, intothe vertica l alveo lar pr ocess, where i t p ro­cec ds towards the palatal pe riosteu m. Th isdescribes the first stage of palatal d isplace­ment.

The palatal periosteu m may then halt fu r­ther progress o f the tooth, o r it ma y alte r theeru ption path to a more ho rizont al di rection,across the pa late. In eithe r instance, this maythen be defined as a first -stage palatalimpaction.

PALATALLY IMPACTED CANINES

Alternatively, the palatal periosteum mayguide the develop ing canine downwa rds. Thealveolar process in the canine reg ion isv-shaped in cross-section, such that, withcontinued vertical movemen t, the progres·sively narrowing alveolus will tend to gu idethe abe rrant canine in a buccal/labial di rec­tion. These corrective movemen ts of thepala tally d ispl aced canine arc the characteris­tic featu re of what may be termed the firststage of palata l disp lacement with secondarycorrection (Figs 6.6a-d ).

In cases of conge nital absence of the lateralincisor, a canine that was not palpable buc­cally at any po int in its earlier developmentmay often be seen to finally erupt moremesially than normal and in the line of thearch. In the presence of an over-retaineddeciduous latera l incisor or canine only, thecorrect ive movemen ts of the canine lead tothe initiation of root reso rption . Following theshedd ing of the deciduous tooth or tee th, thepe rmanent can ine may then erupt into theline of the arch.

If a late-developing lateral incisor is pre­sent, it will now lie directly in the pa th of thed isp laced canine. The physical presence of thelateral incisor will bring an abrupt stop tothese cor rective movements, an d any furthervertical developmen t of the canine may onlythen be on the palatal side of the dental arch,completing the second stage of palatal dis­placement.

In sum ma ry, therefore, the 'guidance the­ory ' comprises five clemen ts.

1 Normal I'rll pticm. It ado pts Broadbent'soriginal view that, given the time ly andnorma l development of a lateral incisor,guidance fo r the canine is provided and abuccal path of eruption is to be expected,with the tooth palpable early on .

2 First-stage impaction. It offer s an exp lana­tion fo r the loss of guidance at a criticaltime in the nor mal deve lop ment of thepermanent canine, wh ich leads to adeflection of the developmental pa th ofthe too th, causing it to mo ve pa lata lly.This aenologtc facto r may be created by acongenitally missing lateral incisor or bya la te-d eveloping. an oma lous lateral

incisor. In the event that no verticalmovement of the canine into the alveo larprocess occu rs, the resu lt may be a ho ri­zontal palatal impaction.

3 First-stage impaction with St'collJary correc­tion. It goes on to explain the cor rectiveinfluence of the ver tical alveolar process,wh ich redi rects the canine on a morefavourable path. This scenario may bedifficult to d iagnose accurately, and theclinician must d raw his or he r own con­clusions from the further progress of theimpacted tooth, which may be palpable,low down on the palatal side, before itfinally erupts close to the line of the arch.The tooth may then spontaneous ly movemo re buccally, in the absence of a latera lincisor, to reach the occlusa l plane in aclose-to-normal bucca-lingual positi on.

4 Second-stage ill/paction. Self-correction ispreven ted by the p resence of an anom­alous and late-developing lateral inciso r,rcdcflectmg the tooth further palatally.This may be termed second-stage dis­placement, and is an actiologic factor tha tis not seen where the lateral incisor isabsen t.

S Second-stage impactioll wi tll secondary cor­rection. As we sha ll see later, in the dis­cussion of trea tment timing. extraction ofa deciduous canine, or even the lateralincisor itself, may often lead to spon ta­neous eruption of the impacted too th.

Small, peg-shaped and missing teeth arcmo re frequent findings among females thanamong males, in the rat io of 2 : 1.Furthermore, the maxillary permanen t canineerupts ear lier in females, which could meanthat earlier lateral inciso r gu idan ce will benecessary for its norm al eruption. These factsprovide the hypothes is with some support inexplaining why palata l canines a re more fre­quent in females and why anoma lous lateralincisors are a mo re pow erful causal agenttha n congen itally absent lateral incisors .

It is quite clear that hered ity plays animportant role in this hypo thesis. Theassumption is tha t the genetically dete rminedfactors (small, peg-shaped , missing lateralincisors, etc. ) provid e an env ironmen t that

93

94

[a}

« j

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(b)

(d )

Fig ure 6.6

(.:1-0:1) 5o.-ri.11 radiographs ~h<lwin~ thl' rdationship of an uneru pted canine to a late-developing and p.·~-sha pt.>d late ralinci"o r. (d) Thl' two tee th have eruph'd imd arc supe rimposed on mit.' another. At clinical examination, bo th eruptedcallinl'S 1'\"E'n' found to be on tilt' p.l l,]lal "idl.'.

PALATALLY IMPACTED CANI NES

leads to a loss of guid ance of the canine, itsabnormal pa latal path and impaction .

Hered ity

Given the strong hereditary influence inpalatal canine d isplacement, there are thosewh o believe th at th is is the p rindpal factorinvolved and d ismiss othe r relat ionships assecondary or as similarly linked hereditaryfacto rs. In other words, the palatal can ine isanother link in the chai n of genetically linkedphenom ena .

In a stu d y of th e families of ch ild renaffected by pa latally d ispl aced maxilla rycanines (Zilbe rm an et al, 1990), a search wasmade dillOn!; the paren ts and the siblings forthe related anomalies to which we ha vereferred above. The p revalence of sma ll, peg­shaped and missing lateral inciso rs, late­develop ing dentitions and othe r missing tee thamong these d ose relatives wa s very high, inad d ition to palatally im pacted canines.

Th is evid ence points to he red ity as thecausa l agen t for these associa ted pheno mena.We have contended that the ir presen ce ere-

ates an environ ment favourable to the devel­o pmen t of palatally d isplaced canines, and , aswa s to be expected, this phenomenon wa sfou nd to occu r in an unusu ally high p ropor­tion of these cases. The view that these phe­nomena are each genetically determined .includ ing the canine d ispla cement, and fre­quen tly occu r togeth er {Bjerklin et al . 1992;Peck et al, 199·1. 1995), is eq ua lly tenable, bu lwo u ld ap pear to be an oversimplification .The fact thai the ext raction of ad jacen t decid ­uou s cani nes or anomalous latera l inciso rsgreatly improves the chances of canine eru p­lion would lead us to belie ve th at local factorscannot be ignored as exer ting a powerfulinflu ence on the aetiology of (imineimpact ion .

Peck ct al (1994) have s tud ied the rran spos t­tion of maxillary pe rmanent can ine and firstp remola r (Fig. 6.7), and have fou nd a stronghered itary influence in its ae tiology. Since thistype of cond ition of the canines can not becon strued as deriving from guida nce fro m thelateral inciso r, and cannot be influenced inany way by the size, form o r timing of thedevelopment of that too th, this has been used

95

Figu re 6.7

M.n i1l.u y c,Ulil\O.· /fi~t premola r transpos ition. An example of hereditary primilry tooth germ displacement.

96

as .1 mod el to refute the 'guidance theory'.However, there is no basis for comparingtransposition w ith palatal displacement, ren­dering the comparison invalid (Becker. 1995).

Other forms of maxillary canine positionalanomaly do occur from time to time. whichare d ifficu lt to equate wit h the mo re usualpattern of palatal or bucca l disp lacement.Genetic factor s see m likely to be the govern·ing factors, in which the entire too th islocated in an abnormal position. In thesecases, it seems that the original site or or ient a­tion of the anlage, from which the toothdeveloped. was abnormal. Thus we occasion­ally come across pa tients in who m there isadequate space in the ar ch for the ideal erup·Hen and alig nment of the maxillary perma­nent canines, ye t these teet h erupt buccallyectop ic (Fig. 6.8). Additionally , the eruptionoccurs relatively high in the alveolus an d thetoo th has no mesio-d istal contact with itsimmediate ne ighbou rs. This rep resen ts ananomaly analogous to the can ine-first premo­lar transpos ition cases (Peck et at 1993),although its expressi on is much milder.

.. "" " - , ' "r .. '. '. ...

\.'"\ '- --- .~ ­.

Figu re 6.8

Thc canine has developed in an abnormal loca tion,representing another exampl... of primary tooth genndisplacement.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

It is clear that there is a particu lar geneticfactor that has p roduced these unusual andvery specific can ine loca tions (Fig. 6.9). This isquite d ifferent from the more frequent buc­cally placed canine, which is the product ofcro wding, and its position is d ictated by theamount of space available for it in the archand by a d irect interp roximal contact w ith theadjacent tee th .

We may prefer to define th is rare cond itionas primary tooth-germ d isp lacemen t, in or derto d istingui sh it from other and more com­mon fo rms of displacement, which have anen vironmen tally influenced aetiology.

The vas t majority of palatally d isp lacedcan ines show the root ape x to be ideallyplaced , in the line of the arch (Becker, 1995).Experience shows th at extrusion and tippingof the crown into its pl ace in the ar ch is usu ­ally sufficient, with little or no roo t torquebeing requi red in most cases. Th is ind icateswhere the tooth 'is com ing from', and it isreasonable to ass ume that local causes havebeen ins tru mental in its deflected path oferuption .

COMPLICATIONS OF THE UNTREATEDIMPACTED CANINE

Morbidity of the deciduous canine

Early mor bidi ty of the deciduou s ca nine iscommon for tw o reasons. First, its roo t maybecome marked ly resorbed, crea ting consid­era ble mobility and eventual shedd ing, with­ou t the possibility of replacem ent by thepe rman en t tooth. This crea tes a problem interms of restoration, since the space is usua llytoo small for a satisfactory replacement eitherby the mispl aced permanent canine or bysome form of artificial fixed bridge pont ic orimplan t.

The seco nd reason that such a tooth maynot survive relates to its relatively high sus­ccptibility to interproxima l (particu larly d is­tal) caries. In Israel, it is still commo n to sec afairlv extens ive d istal cavitv in this too th ataround the age of 11 or 12 onwards, whichm ay have been deli berately left untreated by

PALATALLY IMPACTED CA NINES

(.) (b)

Hgure 6.9

(a,b) Bilateral primary tooth germ displacement seen on pano ramic and lateral skull films. The condi tion is undergenetic control .

a general practitioner who was unaware ofthe likelihood or existence of impaction of itspe rmanen t successo r.

Cystic change

Loss of vitality may occur very early on in thecarious process, in the deciduous canine teethowing to the narrowness of the hard struc­tures of these teeth and the relatively largepulp. Necrosis of the pulp and per iap icalpathology may be asymptoma tic.

Under these circumstances, there may be adirect in terconnection between the apicalpa thology and the follicular sac sur roundingthe impacted canine. This may stimula te anenlargement of the follicular sac, whi ch isclea rly SL'€n on a periapical radiograph. Itma y also undergo cys tic change, to produce adentigero us cyst (Fig. 6.10). This may alsooccur without any relation to pa thosis of thedeciduous canine. In strictly radiologicalterms, an enlargement of the follicula r sac tobeyond 2 or 3 mm is generally cons idered torepresent cystic change . In ra re cases, these

Figure 6.10

A dentigerous cyst su rrounds the crow n of an impactedcanine .

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH98 -.::.:::..::.:-.::.:==== = .:..=-.::.:.:..== = "-

cysts may expand at the expense of surrou nd­ing maxillary hone and di splace the can inehigher and high er in the max illa, as ha s bee ndescribed in Chapter 1.

Alternatively, and rarely, the chron ic peri ­apical lesion on the deciduous canine mayitse lf become cyst ic -.1 rad icular cyst - and itssubsequen t enlargemen t may displace thead jacen t teeth. includ ing the palatal canine.

Crown resorption

The reduced enamel ep ithe lium surro undingthe completed crown of .1 tooth may degener­ate wit h age, and its integrity may be lost.

This allows bone and con nec tive tissue tocome into d irect con tact with the crown of thetoo th, and os teoclastic act ivity w ill lead toresorp tion of the enamel and {ts replacementby bone - a process kno wn as replacementresorption. Over a long period of time,repea ted radiographs o f the too th will showthe enam el becoming less and less cont rastingin densit y, h ighligh ting this bone -for-enamelsu bstitution (Fig. 6. 11). Subsequent su rgica lexposu re of the crown of this too th will showa pitted su rface, wh ich is d ifficu lt to sepa ratefrom the su rro unding hard and sparse softtissues .

This finding seems mort:' likely to occur inadult pa tients in whom the impaction hasbeen left untreated over two or th ree deca des(Azaz and Shteyer , 1978).

Resorption of the lateral incisor root

Figur l' 6.11

l'c napical view of maxillary incisor .l rl',l in a 63-year-oldfemale. ~how in~ advanced rcscrpnon uf the cr owns uftwo imp.lel''ll caruncs . Th., ("Jlidlos uf bot h tedh Mealm ost completely absent . and lhe kdh Me very radiclu­cent, with pour defin ition .

Little is known about the reasons for theresorpt ion of the roots o f deciduous tee th thatleads to thei r eventual shed di ng and why thisdoc'S not normally occu r with the roots of per­manent teeth . Nevertheless, the p roximity ofthe foll icu lar S.1C of an unerupted perma nenttoo th to the roo ts of its deciduous p red ecessorappears to be the trigger that initiates thep rocess o f roo t resorp tion, p robab ly as theresu lt of pressu re. The continu ity of thisreso rption proct"ss is then maintained by thefu rther ad vance of the erupti on of the perma­nen t tooth, which moves into new areasvacated by the reso rbin g root.

Unde r certain condit ions, however, thep resen ce of ,111 unerup ted perm anent can inetooth may lead to the resorption o f the root ofthe adjacen t lateral (Fig. 6.12) or cent ralincisor. Furt hermo re, an d in a man ner similarto that see n w ith deciduous teeth. theprogress of this undesirable phenomenondepends on fur ther eruptive movemen ts onthe pa rt o f the imp acted tooth . If the impactedtooth is removed or its path redirected, theresorp tion process usually ceases.

In this context, it is perhaps pertine n t tocomment that the maxillary canine, which isthe onl y pe rmanen t tooth whose erupt ion

PALATALLY IMPACTED CANINE S

may cause resorption of the roo ts of neigh­bouri ng tee th to any significan t degree, is alsothe only pe rm anent too th that normallydevelops in close relationship w ith the devel­oping apical areas of the roots of other pcrma­ncnt teeth. The premolar teeth d eve lop in arest ricted area, encompassed by the roo ts ofthe decid uous molars and at a distance fromother pe rmane nt tee th . The central incisorsan d first molars erupt before their ad jace ntneighbo u rs, and the lateral incisor is relatedto the neck area of the crown of the centralincisor. The can ine, howe ver , is closelyrela ted to the roots of the adjacent la teralincisor an d first premolar, whil e it is stillfairly h igh in the max illa during mo st of itseruption period .

Marked resorp tion of the lateral inciso r rootis no t com mon and only a minority ofimpacted can ines seem to be associated w ith

Figure 6.12

The imp.Ktl-.J c.mi ne cro....n is surrounded by ... largedenngcro us cy"t. ... nd there is "'SSlIcl.ltl-.J root rcsorpnonof both the deciduou s canine (10 bl- l·X!"--'CIl-.J) an d thepermane nt la teral incisor (pa thologjcalj.

it (Ericson and Ku rol, 1987a,b, 1988a ). When itoccu rs, however, its onse t ma y be rapid andits conduct aggressive (Brin et al, 1993a ). Anindelib le impression is usually left on theoperator who ha s to deal wi th this eventual­ity . Thus ea rly identification o f the presenceof lateral incisor root resorption is im portan tin order no t to d elay the commen cement oft reatment to a time when the su rv ival of animpo rtant ad jacent too th ma y be th rea tened .For this rea son. wh ile extra-oral radi ograph icvie ws of the impacted tooth ma y offer thebest means of locating its positi on accu rately,a good periapical view shou ld alwa ys betak en and studied, with th is possibility inmind.

It shou ld be rem embered, however, thaton ly resorp tion of the ap ical or interp roximalsurfaces of the roo t of the lateral incisor willbe visible on the pe riap ical radiograph . Giventhat the impacted can ine is most frequentlyrela ted to the palata l sur face of the roo t of theincisor, it is clear that man )' areas o f reso rp­tion of this aspect of the roo t surface willescape recogn ition, o ften until they are in afairly advanced s tage, using conventionalradiograp hy . The use of computed tomogra­phy (CT) is the on ly availab le method for d is­covering root resorp tion of the palatal o rbuccal aspects of the roo t of a too th (Ericsonand Kurol, 198Rb).

Several stud ies h ave been cond uc ted to tryto identify those lateral incisors that arc mostliable to be afflicted by roo t resorp tion. Thesehave largely resea rched pa rameters concern ­ing the impacted too th, su ch as the s ize of thefollicular sac and cys tic chan ge, none ofwhich ha ve sh ow n any correla tion with rootresorptio n.

Earlier in th is chap ter, the actiologtcal linkbe tween palat al canines and anoma lous lat ­era l incisors was di scussed. It was po intedout that, in a sam ple of patients wit him pacted canines. almost half of the adjacen tlateral inciso rs were anomalous. The sameg roup of researchers (Brin et al, 1993a ) tes tedthe occurrence of root resorption aga ins t theva rious categories o f la teral incisor (no rmal,small and peg-shaped ), to see if an y one ofthem was more susceptible than the others. Astrong correlation of the occurrence of rcso rp -

99

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH100--- - --- - - - - - - - - - - --- --tion with those pa tients whose latera l incisorswere norm al in size was found. While resorp­tion of the lateral inciso r root has been shownto occur in 12% of cases in the t D-n-year-oldage group (Ericson and Kurol, 1987a), when itdocs, it is far mo re common in a normallysized. la teral incisor tha n with a small or peg­shaped late ra l incisor. When a norm ally sizedlatera l incisor is associated w ith an adja cen tpalatally impacted canine, the chances ofreso rp tion of its roo t arc 7 times greater tha nif the lateral incisor is small or peg-shaped!

DIAGNOS IS

Unerupted pe rma nent maxillary caninescause the patient relatively few problems,unlike the impacted mandibular third molar.A retained deciduous canine may have a rela­tively poor appea ran ce compared with aproperly aligned perm anen t canine, but mostpatien ts do not seek treatmen t for theretained deciduou s can ine. The d iscovery ofpalatal impaction is therefore usua lly madeby the general dentist, at the time of routinedental exa mination.

Inspection

The maxillary pe rmanen t canine normallyerupts at a denta l age o f abou t 11 years. Itsnon-appearance at this age should invite clin­ical inspection and radiographic investiga­tion, especially if its an timere is present.

The maxillary incisor teeth are normallyflared laterally and spa ced until the age of 10years, as described ear lier . Shou ld this situa­tion st ill be t rue by 11 or 12 yea rs, the clini­cian shou ld be susp icious, since this meansthat there is a detail missin g fro m the mecha ­nism that smoot hly transfers the ugly d uck ­ling stage into th e final ad ult alignmen t. withinterproximal incisor con tacts. Ind eed , ares ultant persistent med ian diastema may bethe factor that brings the patien t to the office,unaware of the impacted canine. to requesttreatment.

It is un like ly that a m issing lateral inciso r ora frankly peg-shaped incisor will be over­looked. Nevertheless, care should be taken toexamine the size and sha pe of exis ting lateralincisors. Central and latera l incisors whosecrowns have mesio-dista l straight or slightlytapering sides and lack the classical proximalcontou r are usually sma ll tee th and oftendevelop late. Some of these ar e peg-shaped, acondition defined by their widest mes io-d istald imension being at the CEJ.

Furthermore, the discovery of a late­developing dentition and a dentitio n in whichthere are missing tee th, other than the lateralincisors, sh ou ld also be trea ted with a deg reeof cau tion. All these factors have been linkedwith palatally d isp laced canines, and this pos­sibility shou ld be thoro ugh ly inves tigated,both at the time wh en the phenomena arefirst not iced and in subsequent follow -upexamina tions that have been sched uled tooversee the smoo th changeover from themixed to the permanen t den titions.

Abnormally positioned and uneruptedcanines freq uently affect the positions ofneighbouring tee th, pa rticularly lateral in­ciso rs. We have alread y pointed out that theroot of the canine is usually in the line of thearch, with the crown mesially displaced. inaddition to its palatal tilt. This brings it intoclose relation with the palatal side of the lat­eral incisor, often d isp lacing its roo t lab ially.Clin ically. this will be identified by a lingu altilt of the crown of the too th, sometimes into acrossb ill' relationsh ip.

Palpation

We have poin ted out in the previous chapterthat, under conditions of normal devel op­ment, the tooth is palp able bu ccally above thedeci d uo us can ine for 2 or 3 years prior to itseru p tion. The buccal as pect of the alveo lusshould be palpated above the attached gin­giva and up to the reflection of the oralmucosa. A wide convex contour of the bone isind icative o f the canine, immediately beneath.Care should be taken not to confuse this withthe narrower profile of the root of the decidu-

PALAT ALLY IMPACTED CAN INES

ou s canine. In the event that this contour isconcave, the palatal sid e of the alveolarprocess should be palpated to see if there is aclue to its location there.

The deciduous canine sho uld always betes ted for mobility. If this test is even mildlypositive, it will suggest that the pe rmanentcanine is fairly close to the desired er up tionpath and that severe disp lacement is unl ikely.ln th is situat ion, the unerupted canine maynot be palp able on either side of the alveolarridge.

Radiography

As we sha ll see later in this chapter, to planthe strategy of mechanotherapy properly fora particular case and to obtain a pre treatmentassess ment of the pe riodontal prognosis ofthe treated result, it is essential to know theexact positions of bo th the crown and the rootape x of the un erupted tooth. A single periapi­cal rad iograph is essential to iden tify patho­logy, such as root resorptio n, obstruction andcystic change, but it should be sup plementedby other films that wil1 help to locate pre­cisely the unseen tooth.

The use of a second periapical radi ographin the parallax method has the advantage ofsimplicity of technique, and provides both theorthodontist and the surgeon with importantinfonnation regard ing positioning, althoughthe precise locations of crown and apex a red ifficult to comp ute from these pictu res. Atrue lateral view (as seen on the lateralcephalogram or on a tangentia l film) pairedwith a vertex occlusal or postero-anteriorcepha lometric view Me technically more diffi­cult to obtain, bu t will provide the requi redaccurate three-d imensional positional infor­mation of the unerupted too th in its simplest­to-understand form.

A panora mic rad iograph, in its cent ral po r­tion, shows the inciso r region in the pos tero­anter ior view, an d will ind icate a palataldisplacement as an overlap of the Impactedcan ine with the roots of the incisors. This isby far the most popular method used today.However, the canine /premolar/ mo la r areas

arc recorded 0 0 the same film in the latera l(sagittal) plane and not in the ante ro-posteriorplane, as the consequence of the rotation ofthe X-ray beam . Thus the film ma y be mis­lead ing in relation to the ca nine that is notmesially d isp laced.

TREATMENT TIMING

From the age of about 9 or 10 years, it is usu­ally possible to pa lpa te a normally develop­ing maxillary permanent canine tooth on thebuccal side of the alveolus, high above itsdeciduous predecessor. The greater thedegree of crowding, particular ly after theeruption of the first prem olar, the more buc­cal is the displacement and the more palpablewill the canine become, as its eruptive processbrings it furthe r and further dow n on thatside of the arch.

In the event that the tooth is no t pa lpable atthis age, radiographs sho uld be taken to assistin locati ng the tooth accu rately and to secureothe r information regard ing the presence,size, sha pe, position an d sta te of developmentof indiv id ual unerupted teeth and any pathol­ogy . In a patient younger than 9 yea rs, theradiographs will not usua lly show abnormal­ity in the pos ition of the unerupted canineteeth, even if the canines arc no t palpable andeven if they are destined subseq uently tobecome palatally d ispl aced .

Many of these no n-palpable can ines willfinally e rupt in to good positions in the den talarch, in their due time, provided that there islittle or no mesial and pa latal displacem ent ofthe crown of the unerupted tooth. It ma y beargued that even canines wi th an initial mildpalatal displacement will achieve sponta­neo us eru ption and alignment despite a firststage disp lacemen t, if they un de rgo sec­ondary correction (see 'Guidance theory ofimpaction' in the section on Aetiology). Othercanines, however, will not erupt, and theirpositions may worsen in time, as may be seenin follow-up rad iographs. If it were possibleto distinguish between the two early enough,a line of preventive treatment migh t beadv ised.

10 1

102

Preventive treatment and its timing

Using panora mic radiog raphs of young pa ­tients in the m ixed den tition , Lind au er et a\(1992) were able, to a low degree of rel iability(78')\,) on ly, to p red ict palatal impaction onthe basi s of can ine ove rlap of the root of thelateral incisor.

Extract ion as a means of prevention:dec iduous canines

As we ind icated ea rlier in th is chap te r, se v­era l aut ho rities (Ericson and Kurcl, 198Bc)prescribe the extrac tion o f the de ciduouscanine teeth in an atte mpt to encou rage th epermanent can ines to erup t. They haverecom mended seeing the patient and d iag­nos ing the pa latal positioning befo re the ageof 11 wars, and have show n that extractionpe rformed at thi s time offers a good p rog ­nosis for the.natu ral eru ption of the canine,with 78% o f the canines in thei r sam ple erupt­ing into a clinically correct po sition. Cautionmus t be ad vised in interpreti ng these resu lts,howeve r, since the au thors di d not study anuntreated con trol group, and thus Me not in aposition to d eter mi ne jus t how many of theseteeth wou ld h ave eru pted wit hout this pre­ven tive treatment (Lindaue r ct a t 1992) (Figs6.13 and 6.14).

Fro m their studv. Ericson and Kurol con ­cluded that prognosis becomes less favour­able as the pal atally displaced canine's medialoverl ap o f the la te ral inciso r roo t increasesand as the angle between the long axis o f thecanine and the mid-sagittal plane widens.They also no ted that, if posi tiona l im prove­ment of the canine was not evid ent wi th in 12months of the extraction, it was un likelv thatimprovement wou ld occu r. -

From this di scussion an d fro m some con ­siderable an ecdot al clinical experience, wemay assume tha t, under certain circum ­stance..'S, the extraction of a maxilla ry decidu­ous canine ma y be a useful mea sure in thep revention of ins id ious canine im paction . Toach ieve max imum reliab ilit y, the followingcon di tions sho uld be met before extraction isad vised.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

1 The d iagnosis o f pala tal di splacementmus t be made as early as possible.

2 The patient must be in the 1D-13-year agerange, p referab ly wi th a delayed d entalage .

3 Accu rate iden tification of the po sition ofthe apex should be made and confi rmedto be in the line of the arch.

4 Medi al overlap of the une ru p ted caninecusp tip shou ld be less th an half-wayacross th e roo t of the lateral incisor. onthe pan ora mic view .

5 The angulat ion of the long axis should beless than 55° to the mid-sagittal plan e.

The latter tw o items on th is lis t represen t con­ditions th at, if no t fu lfilled, may still lead tospon taneous eruption and alignment, so that,while the cha nces are reduced, extraction maystill be worth consideri ng.

Given that there is no tr u ly reliable methodof early detect ion of a potential pala ta l d is­placement (Linda uer et al, 1992), the claimtha t pre-emptive ex traction of the d ecid uou scanine has elicited the normal erup tion of thepe rma ne nt can ine mu st be viewed with somereservat ion , on the bas is of the present sta teof our know led ge. Clin ical experience wouldlead us to be encou rage d by th e proced ur e inmany cases, bu t an accurate assessment of itsefficacy has st ill to be determined .

Extraction as a means of prevention: firstpremolars

Within the minority g rou p o f patients withimpacted canines who are cons idered to beextraction cases, usually because of incisorcro wd ing, a Class II rela tion or bimaxilJaryprotru sion, the ch oice of teeth for extractionusually devolves upon the first or second pre­molar tee th. The reasons for this particularchoice are bound up with the history of ortho­dontics itself. Th is offe rs mu ch potential be n­efit to the d isplaced canine, sin ce thep roximity of these teeth to the canine facili­ta tes the immed iate provision of space closeby. It also affords considerable op portun ityfor a spon taneous imp rovement in the canineposition (Fig. 6.15), during the early levellingand align ing stages of the mecha notherapy.

PALATA LLY IMPACTED CANINES

(.)

(b )

Figu re 6.13

(a) A cnse diagnosed from thi s panoramic view ,15 hav ing bila teral pa lata l canine dis placement and referred for extrec­tion of the deciduous canines. (b) A year later, a repeat film shows gTl'a t improvement in the position of both canines,and normaleruption of the ca nines is imm inent, despite the fact that thl' decid uous canines had nu t been extracted .

Extract ion as a means of prevent ion: lateralinc isors

We have noted. above that many of theimpacted cases that we see are associatedwi th anoma lous lateral incisors. At the end ofthe treatment p rocedu re, it is often necessaryto alter the shape of these teeth by prosthetic

crowni ng. laminates or com posite bu ild -ups.in o rder 10 make them aesthetically accept­ab le, particula rly those that arc peg-shaped ,We have pointed ou t earlier that palata lcan ine cases generally have spaced denti­tions, com prising small teet h, such thatcro wd ing and the need for extractions in theovera ll tre atment is unu sual. Nevertheless, if

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH104--- - - - --- - - - - - - ----'----

(b)

Figure 6.14

( .1 ) A case of ea rly cro wd ing treated by extraction of fourdeciduous canines, to relie ve cmwding at age g yl'':us. Nohint of impending palatal displacement of the canine isdiscernible on this panoramic film. (b) One yeilT1,l\er, theincisors are al igned and spaced . Extraction of th.. fou rde ciduous first m olars (the second st age of seria l cxtrac­lion) was advised . (c) The panoramic view taken a yl' arla ter reveals the max illa ry right canine in a p.:d .ltdlly di s­pla ced location, despi te ea rly extr,lelion of thl' ..k d duouscanine. Treatment of this case may be seen in Fig. 6.35.

(,)

extraction has to be mad e to trea t the overallmalocclusion in these cases, considerationshould be given to the extraction of these mal­formed lateral incisors, as an alterna tive tothe convention al but healthy and an atomi­cally perfect first p remolars.

We have described how the guid ancetheory of eruption of the canine offers acogent argument of how palatal d isplacementof the canine may occur. In those casesdescribed as a first-stage displacement, it waspointed out how the vertical wall of the alve­ola r p roce ss on the pa latal side stee rs the ver­tically and palatally di rected eru ption on amore bu ccal cou rse, to produce a secondary

correction . Th is continues u ntil the develop­ing cani ne comes up agai ns t the root of a la te­developing lateral inciso r, wh ich forms aba rrier to its fur ther p rog ress. A second sta geimpaction is thus created.

Logically, the removal of this barrier shouldlead to a natur al imp rovement in the positionan d eruption status of the impacted canine ­the second-stage im paction with secondarycorrection. In pract ice, clinical experienceshows this to be largely tru e (Fig. 6.16).

Extraction of the la te ral incisor is no t a suit­ab le procedure in most cases, bu t in thosepa tients where it is ind ica ted, treatment timemay o ften be ve ry short. Ho wever, a nor-

PALATALLY IMPACTED CANINES

mally sized canine adjacent to a centralincisor may create a marred and unsatisfac­tory appearance, particularly if the centralincisor has a poor profile (frequently seen inthese cases). Furthermore, by lining up thecanine and first premolar in place of the lat­era l inciso r and canine, a discrepancybetwee n up per and lower tooth sizes maycompromise the occlus ion.

Orthodontic space opening

The preventive measures that we have des ­cribed up to this point have involved theextraction of teeth ad jacen t to the impactedon ly, nam ely the deciduous canine, the lateralinciso r or the first premolar, in the hope thatthe impaction will resolve spontaneous ly. Analternative and sometimes supplementaryline of preventive treatment involves the gen­erous opening of space for the teeth, usingorthodontic appliances. One of the primary

functions of orthodo ntic treatmen t prepa ra·tory to the treatmen t of impacted teeth, is thecrea tion of space in the de ntal arches for theimpacted teeth. When this is done, une ru ptedteeth may often steadily improve their posi­tions, as will be seen on repea t radiographs,and may often erupt without su rgical inte r­vention (Fig. 6.17). This is clearly due to analtera tion in the relation of the canine crownto the roots of the incisors and a concomitan talteration in the gui dance influence of theseteeth. It provides further evidence to sup portthe guidance theory of impaction.

Timing of mechanotherapy

Most cases are not identified early enou gh totake ad van tage of these preventive steps, andwill usually be seen for the first time by theorthodon tist only after the initial and, by

(b)

Figure 6.15

(a) The left side of a Class II di vision 1 case w ith bila tera l maxillary pa lata l c.:mifl<,' im paction. The maxi lla ry deciduou scanines, deci d uous second mol ars and first premolars were extracted and an a ttachment placed on ea ch of thl' impactedcanines. No active orthodontic treatment w as com menced . (b) The same side seen 14 wee ks la ter . Both canines andsecond premola rs have erupted spontaneously and to a s imilar degree. Applianre thera py wa s ini tia t~-d at this poin t.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH'06

-------------~~------=--------------

,.) (b)

'<' 'd'

Figure 6.16

(d,b ) A pala tally impacted rihht can ine is .1Jjaa·nt 10the pe g-shaped right lateral incbvT. while th., oppo­site canine has erupted in place of th... am"l'nila llyabsent la te ra l incisor. (c.d ) The periapical films usedto diagnose the pa lata l position of the canine by paral­lax. At the time of extraction, th., palata l posit ion ofthe can ine was confi rm ed clinically. (e) Thl' cani nl' haseru pted on the bu ccal '>ide.

PALATALLY IMPACTED CANINES 107

(., (b, Ce'

Cd' C" (0

Cg' Ch, (i)

Figure 6.17

(J-c) A Class 11 , division 2 case with cro wding in th e maxillary arch an d SI'\'l'1'l' Sp"Ct.' loss du e to "ilrly ,'x lraction in theman dibul ar arch. (d) A panoramic view shows a pala ta lly displaced right maxillary canint'. (I') A similar ra d iographta ken followin g distal movement of a ll four mola rs and space reo pen ing. No t,· Improved po siti on s and prospects of allthe une ru pt ed teeth, particu la rly the canine. ( f~i) The final den ta l a lign m ent an d occlu sion.

THEORTHODONTIC TREATMENT OF IMPACTED TEETH108________ _ _ ::..:.....---=..::.c:.----'----=--------'--"--------=--='____''=____

then, more obvious diagnosis has been madeby the generalis! or pacdodont ist. A coexist ­ing malocclusion has often been the reasonfor the pa tient req uesting treatment, an d theimpacted tooth will have been d iscoveredonly as the result of the orthodontist's rou tineclinical an d radi ographic examinatio n.

The pa tient is gene rally in the full penna­nent den tition stage, with the exception of thedecid uo us canine o f the affected side .Sometimes, the remainder of the dentit ion isin a close.... to-ideal alignment and inter-a rchrelat ion, as has been poin ted out earlier,although a minor degree o f local toothmalalignment may often be seen. This gener­ally includes a laterally flattened or collapsedar ch form (Fig. 0.18) and spclce loss in theimmediate Mea, wi th space opening m oremes ially (Oliver et al, 1989). In only about15% of the cases ( lacoby, 1983; Becker, 1984) isactual crowd ing presen t.

The periapical rad iographs should be care­fully scru tinized to di scover any evidence ofresorp tion of the latera l incisor root s. Shouldthis be S(.'C'n, orthodon tic treatmen t, des ign ed10 rapid ly deflect the developing canine aw ayfrom the incisor, should be undertaken as

Figurc b.18

A pre formed archwire blan k laid over the occlusal su r­fan'S of the teeth closely ccn torms to the den tal arch,exCt.>pI: in the area of the impacted canine. wh ich showslateral Ilatt erung.

soon as possible. If the resorpt ion is ad­vanced, cons ideration should be g iven toextr action of the lateral incisor, in the rela­tively unlikely event that the case is an extrac­tion case.

For the most part, however, th ere is ra relyany reason to hurry int o treatment simplybecause pa latal displacement has bee n di ag­nosed . The patient must first be prepared forthe treatm ent that is to be unde rtaken, ini­tially by explaining the natu re and ramifica­tions of the problem, using the radiog raphsand plaster models as visual aids. The princi­pal function of th is exercise is to overcome acomplacency tha t most of these pa tien ts have,since their p roblem is one in which the facialappearance and oral function are rarely com ­prom ised. The aim is to insp ire motiva tionand the necessary fu ture cooperat ion.

The dentition must then be protectedaga inst the incipient da nge rs that the place­men t of appliances is likely to genera te. Thenecessary measures include a high level oforal hygiene and the usc of appropriate fluo­ridating procedures, both at home and in theden tal office, as well as the treatment of anycarious or periodontallesions .

After a period. of a few wee ks, duringwhich the pa tien t will, it is to be hoped, haveundertaken these oral hygiene responsib ilitieson a regular basis, an oral exam ination shouldshow pink, firm and stippled gums and anabsen ce of plaque on the tee th . Th is being so,the time w ill be ripe to begin or thod ontictreatmen t. In the non-coopera tive patient,treatmen t shou ld be denied until the abovecond itions arc fu lfilled , Shou ld the dentalawa reness of the patien t be too low for thisever to occur, alternative treatment mod alitiessho uld be considered, particu larly prosth eticreplacement, although, for these to be suc­cessf u l in the long term they may be just asrel iant on oral hygiene as is orthodont ic treat­ment. Nevertheless, an operative decisionmay be delayed for quite a long time, in viewof the relat ively low incidence of morbid ity,provided that period ic rad iograph ic mon itor­ing is performed.

Postponemen t for a few months or even ayea r is rare ly a p roblem in straigh tfor wardorthodontic terms, and if it serves to b ring the

PALATALLY IMPACTED CANINES

patien t roun d to the ways of proper homecare then the time spent will have beenwor thwhile. Unfortunately, as already men­tioned, the denta l development is oftendelayed, which is why these patients reachthe perm anen t denti tion stage with the can ineimpaction diagnosis mad e onl y at the age of14 or 15 years. Thus, from a social po intof view, the patient may be less inclined towea r appliances if further postpo nement isen tailed .

From the strictly developmental point ofview, the best time for therapeutic interven­tion is when the root of any affected too th isof a length that is seen at the time of normaleruption . For the canine. th is is a litt le inexcess of th ree-quarters of the po tential roo tlength, which is virtually always present bythe time the diagnosis of palatal displacementmay be determined .

GENERAL PRINCIPLES OFMECHANOTHERAPY

When a patient arrives at the or thod ontist' soffice and a palatally d isplaced an d un­erupted canine is d iagnosed, treatment mustbe planned in a d isciplined manner. We haveseen in Chap ter 5, in regard to the impactedmaxillary centra l incisor, that orthodonticpreparation of the case is requ ired and thatsurgical interve ntion is not to be undertakenin any haphaza rd or unplanned manner .Appliances that are to be used to dis impact,erupt and align these teeth may also be usedto align the other teeth, with very little mod i­ficatio n. For this reason, the local anomalyand the overa ll malocclusion are usua lly dealtwith together in one full and comprehensiveorthodontic treatmen t plan.

A diagnosis of the overall ma locclusionneed s to be mad e and a problem list set out,which includes the palatal canine. The prob­lem list is then rearranged into a treatmentprio rity list, in wh ich alignment of theimpacted canine should preced e many of theother items to be treated. The same principlestha t were used in the planning of treatment inChapter 5 are equally app licable in the pre-

sen t context, although we shall now be deal­ing with the trea tment of the entire de ntitionand no t merely the area imm ed iately ad jacentto the impacted tooth.

The principles, as they relate to the pal­atally d isplaced canine case, need to be adap­ted to the new circumstances. and maytherefore be presen ted as follows.

1 The app liance sho uld have the capabili tyto kr.>el ami rotate all the tee th in the samejaw rapid ly, and, with controlled crownand roo t movemen ts, to open adequatespace to accomodatc the impacted tooth.As we saw when dealing with impactedincisors, this space is required bo th at theocclusal level and between the roots ofthe adjacent teeth for their en tire length.This stage requires the use of fine level­ling and align ing archwires.

2 With the initial alignment achieved an dno furt her movement of individualerupted teeth need ed, these tee th aretransformed into a composite and rigidanchorage Ill/it, in wh ich each of the teethplays an integral par t. This is done bysubstitu ting the flexible archwires with aheavier wire, whose ga uge is as large asthe bracket w ill take, in orde r to allow aslitt le ' play' of wire within the bracket aspossible, thereby maximizing the anchor­age value of each tooth.

3 The surgical exposure of the crown of theim pacted tooth sho uld be performed in amanner that will achieve a good pe ri­odontal prognosis of the treated resu lt .An attachment is bonded to it and thefl ap fully closed, with only a fine ligaturewire lead ing through the gingival tissueto the re-covered tooth .

4 Using an auxiliary means of traction fromthe now rigid orthodon tic appliance, agentle and continuous light force, with awide range of activity, is applied to thetooth, and is aime d at erupting theimpacted tooth along a path that is free ofobst ruction from neighbouring teeth(Becker and Zilberman, 1975, 1978;Jacoby, 1979; Kornhause r ct al, 1996).

5 There should be filial ddai/illg of the posi­tion of the formerly impacted tooth,

110

together w ith that of <I ll the other teeth inboth jaws. A Class IJ or Class Jll del/tal rela­tion will usually be reduced at this point.However, it may sometimes be treatedea rlier in the firs t of these stages andbefore surgery is con tem plated, for exam­pic when early orthopaedic treatment isto be undert aken with the use of a func­tional or en-b loc headgear appliance, In

the mixed den tition stage.

The re art.' essentially four ways in whichspace may be provided for the palatally dis­placed canine.

Existing incisor spaci"g //lay be closed off bymoving the lateral incisor mes ially.Inciso r spacing is due to the failure ofcompletion of the ugly duc kling stage ofdevelopment (Broadbent. 19~1i Becker,1978). It was pointed out at the beginningof this cha pter that the final stage inanterior space clos ure occu rs when thecanine erupts and influences the lateral

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

inciso r to move mesiall y . It was alsopoin ted ou t that these impacted teet h arein tima tely linked with small and peg­shaped lateral incisors an d w ith smallteeth in general. Th is being so, it is com­mon to find anterio r spacing in thesepatients (Fig. 6.19).

2 tmprooing archform. When the maxillaryperm anen t canine erupts norma lly, itdoes so along a mo re buccal pa th than thedeci d uo us canine and slightly buccal tothe lateral incisor and first premolar,earning the tooth the title of ' corners toneof the arch' . Co mparing the two sidesof the maxillary arc h in a unilaterallyaffec ted patient, we have already pointedout that, in the canine areas, there is amuch na rrower maxillary width on theside of the deciduous canine th an on thenor ma l side. Exploiting the improvementin this archfonn, prod uced by an ortho­don tic appliance, will add two or threemillime tres o f space for the d isplacedtooth (Fig. 6.20).

"j (b} (oj

(Jj [e) (f)

Figu re 6.19

(01-<) In.1<I''<llI.,I,- Sp.KI.' fur un,.rupt,'<.I per manenl cani nes with interinci.....1sp.lci ng. (d -f) The p'-rm.ln,'nt canines in place.,1 th,- cumr l,-lilln of tn-.ltnwnl.

PALATALLY IMPACTED CANINES

Fig\l re 6.20

(a, b) Improving the .uchform bas provid ed adequa te space.

3 Increasing arch length. If crowding is mild ,the use of a headgear is recommended inorder to move the maxillary molars d is­tally. This will provide the extra spacefurther forwa rd, wh ich may then be con­cen trated in the canine area, using amu ltibra ckcted appliance sys tem (Fig.6.21). Trea tment is beg un with finelevelling archw ires, un til the individualtooth heights, bucco-lingual pos itionald iscrepancies and rotat ions have beencorrected, an d uprighting has beenachieved as necessary.

4 Extraction of teeth When crow ding ismo re seve re, part icular ly wh ere there isalso a Class II dent al relation that is to betreated wit h the use of in termaxi11 aryclas tics, the extraction of a premolar too thon each side of the den tal arch in thema xilla and, usu ally, in the mandible willbe required, With the extrac tion of thepremolar, space for the impacted can ineis immed iately and very locally ava ilable,and so app liance thera py is no t needed toprov ide the space. Secondly, followingthe loss of the first premolars, align men t,levelling and rotation of the remainingteeth are very much simplified. Thirdly ,with a local an aesthetic already covering

111

(b)

the area and a surgical wo und inev itable,it is logical to ext ract the deciduouscanine and expose the impacted canine atthe same time, to reduce the numbe r ofsurgical interventions and post-su rgicaldiscomfor t to a min imum. Thus, in ex­traction cases, it may be recommendedthat the surgical exposure be under takenprior to the placemen t of an app liance(see Fig. 6.15).

The achievemen t of good archform is animportan t initia l goal in the maxilla ry arch innon-extraction cases. After the initial levellingwires, a coil spring is placed on a more sub­stantial archwlrc of ide alized form, toincrease the canine space by mov ing the lat­era l inciso r mesially and the first premolard istally, until interproximal contacts areestabl ished elsewhe re in the ma xillary arch.This will usu ally provide more than enoughspace for the uneru pted can ine.

A heavier-gau ge archwlrc is now firmly lig­ated in to the maxillary appliance, and thespace for the canine must he retained. In theva rious edgewise and prescrip tion pre­torqued bracket techniques, as heavy a rec­tangular base arch as poss ible should be used.In the Bcgg and Tip-Edge techn iques, a round

THEORTHODONTIC TREATMENT OF IMPACTED TEETH112 ~:..=~==:.::...:.=====.:::.:.:::..:=:c

(.) (b)

Figu re &.21

(a) An extra-oral hea dgear is being used to move the molars di stally. The tied-in li~l pala tal arch will be removed andus•.,..dlater for verti cal traction Whl'fl the cani nes are exposed. (b) Aft..r the premolars have been moved distally, mon­than-adequate space has been prepared for the unerupted canines, sc...'Il hen' atthe time of their cxpc...urc.

0.020" or 0.022" wire respectively shou ld beused as the base arch, with the addition o fupn gh ttng spri ngs o r torquemg auxilliaries toact as ' brakes', if nec essary.

The space that has been reopened for thecanine may be maintained usin g the same coilsp ring. which will l1L"Cd to be deactiva ted .However , it is d ifficu lt to ad just the sp ring toma intain a space accura tely, and one w ill usu­ally find that the space will increase ordecrease sligh tly over the succee ding mon ths .Furth ermore, a coil spring qu ickly fills withfood particles ond is impossible to clean effec­tively . A mu ch better alternat ive involvesusing a meas ured and slightly curved lengthof s tain less steel tu bing, which is threaded onthe archw lre and is tied o r p inned betwee nthe b rackets of the premolar and lateralincisor, in p lace of the coil sprin g. This adds agreat deal of rig id ity to the archwire in thearea o f g reates t impor tance, and hel ps inres isting d is tortion, thereby providing anexcellent and firm base fro m wh ich to applyforce to the im pac ted canine. Many of thesecanin es have to be moved over a long d is-

tance to bring them in to the arch, and severalwill requi re root movemen t of the d iffere nttypes before they may be properly b rou gh tinto position and the case completed . Thisinevitably expe nd s ancho rage. The measuresand precau tions that we have described willcontribute much to preserving the anchorage.

THE NEED FOR CLASSIFICATION OFTHE PALATAL CA NINE

Dur ing the orthodont ic trea tmen t of a patien t,as with any other prescribed form of med icalor de ntal treatmen t, at tention is paid toachieving the maxi mum benefit that theapproach has to offer, while susta in ingthe minimum possible adverse cha nges in thehealth of the de ntition and its suppor ting tis­sues that may be caused by the treatment. Tothis end, the orthodontist mus t ensure an ade­quate level of o ral hyg iene before and d uringthe period when the proced ures arc per­for med. The forces generated by the appli-

PALATALLY IMPACTED CA NINES

ances must be wit hin certa in limits, compa ti­ble with physiological toot h movement, sothat perma nent and irreversible damage isnot inflicted on the den tition .

In an extrac tion case, the decision rega rd­ing wh ich teeth to extract is usua lly mad e onstrictly strategic criteria, insofar as certainteeth require to be brought to particu larplaces, an d appropri ate an chor teeth need tobe chosen in order to achieve this. Given agood prognosis of each of the tee th in themou th, with no severely carious teeth andexcellent period ontal health, the criteria oforthodontic treat men t strategy are the guid­ing criteria behind th is ext raction decision.

However, when a tooth or teeth are presentwh ose long-term prognosis is in doubt, suchas a molar tooth that is in need of root canaltreatment and a pos t-and-crown restoration,th is becomes an ad diti onal factor that mu stinfluence the choice of tooth for extraction. Itwould not make long-term sense if the imme­diate an d beau tiful ort hod ontic results wereto be based on teeth that would not be pre­sent in the mouth a few years later, whi lehea lthy teeth of excellent prognosis had beensacrificed in the name of strategic conve­nience.

Maxillary canine impaction in a case whereteeth requi re to be extracted as part of theoverall or thod ontic treatment presents a simi­lar d ilemm a. The can ine has a longer roo t andcontributes mu ch to the pati ent's appea rance,par ticularly the smile, which makes it a veryvaluable tooth and one worth the expenditureof considerable effort to brin g it into pos ition .Its substitution by a first premo lar is not usu­ally des irable. It is inappropriate to auto mati­cally and blind ly extract an impacted can inewith a good prognosis, in preference to anerupted first premol ar, just as it is inapprop ri­ate to ext ract a first molar rather than a firstpremolar simply becau se the molar has asma ll occlusal am algam filling. But what ifthe long-term prognosis of the canine is poor,as the consequence of its having been throughthe proces!'>es of surg ical expos ure and ortho­do ntic alignmen t, over the period of manymonths or years that we rt' spent in its meticu­lous alignment? Pe rhaps it wou ld ha ve beenbetter to remove that pa rticular canine at the

ou tset and 10 have brought the first premola rto its place.

Extraction cases arc very much in theminority among patients with pa latallyimpacted canines (jacoby, 1983; Becker, 19s.!),and so, for the most pa rt, every effort mu st bemad e to bring the can ine into the a rch and todo this in a manner that will provide it withits best possible pe riodontal prognosis(Freeman, 199-J).

The clinician mu st carefully assess eachind ividual case, to be in the pos ition in whichan accurate appraisal of the seve ral aspectswhere prognosis of the results of the treat­ment is at stake , prior to the beg inning oftreatmen t. With th is information, the optimaldecision regard ing extraction may thenvalid lv be made.

At the time that the patient 's records arcbeing studied in order to formulate a su itabletreatment plan, it wou ld be helpful if therewere a way in wh ich it is poss ible to assessthe long-term prognosis of an impactedcanine before treatment is started. It is there­fore cruc ial to seek a key that may be avail­able to help us to decide wh ich canines willbe ad versely affected in period on tal terms:

(a) by surgical access to them,(b) by the relative difficulty in orthodonti­

cally mov ing them into align ment.

From the surgical aspec t, which we havediscussed in Cha pter 3, mini mal exposureand full flap closu re (with attendant attach­ment bonding) is the preferred line of trea t­ment , aimed at prima ry healing.

Docs a tooth thai requires a whole range ofd ifferent types of orthodontic movemen t paya periodontic penalty, in the final analysis, incomparison with one that is more simplyaligned?

Teeth that are mechan ically erupted br ingwith them a genero us amount of alveolarbon e. It has been shown in stud ies in Israel(Becker ct al, 1983; Kohavi ct al. 1984a,b) thatthe assisted erupti on of buried teeth with theuse of o rthodontic appliances prod uces a col­lar of alveolar bone arou nd the erupted tooththa t is g reater than tha t seen on normallyeru pted adjacen t teeth. These stud ies haveshown this to be true on ly where surgical

THE ORTHODONTICTREATMENT OF IMPACTED TEETH114-------------'-~--'-'-'-----'-----='--------'---'----'-~"--=---

~

po

- - --

86.."

Pe rcentage

"94

"90

"

Figure &. 22

Bone support tcve ls in the treated canines (light ba rs)compared with rbe norrn ,lIly erupted opposite canines(dark ba r); X. minima l su rgl.'ry and p rimary closure; X..su rgl.'l)· in w him th., follicular sac was removed dow n 10the eEJ; ~.. orthodontic tipping. extrusion and rotationmovement s only; 1\.1.. roo t uprig hting and tor qu eingmovement s. (Adapted from Kohavi et al, 1984b.)

p red ict in which patients resorption will occur.Wha l is found, however, is that the resorptionprocess almost invariably stops whe n ortho­don tie too th movement is completed.

In most pa tients for whom ma jor orthodon­tic movemen ts ha ve been ca rr ied ou t, resorp­tion is exce ptiona lly small and o f no clin icalsign ificance. Neverthe less, the re arc occa ­siona l cases where these ill effects mayaccou nt for the loss of 3 or 4 mm of the origi­nal root length. It also appears th at treatmenttime has lit tle impact on root resorption, evenwhen treatmen t has lasted for 6 years (Beckand Harris, 1994)! In the absence of defini­tive in formation regarding the mechanismsin volved, however, it would seem wise tha t,for those patients who a rc p rone to roo tresorption, or thodontic treatmen t shou ld bekept to a minimu m, bo th in ter ms of du rat ionand simp licity. The optimal res ult for th atparticular patien t may not even come close tothe id eal.

For the resorption-s usceptible case, it cou ldconceivably hap pe n tha t all the p reca u tionsthat we have de scribed may be followedscru pu lously and a good pe riod ontal resul t

~xposurt! was conservative and did no tinvolve the removal of the ent ire follicula rsac. Radical surgery leads to less bone sup­port than is present in a norm ally eruptedtoo th, and considerably less than the m in i­mally exposed impacted tooth.

The most likely exp lana tion for this is befound in the proced u re that prosthod ontistscall ' fo rced eruption' (Ingber, 1974; Stem andBecker , 1980). When one side of a tooth isfrac tured or destroyed by ca ries to below theheigh t of the crestal bone, an inf ra-bonypocket is produ ced . The treatment thai is pre­scribed to eliminate this is to mechanicallyerupt the tooth away from the bo ne marginand to thus o rthodonticallv reverse the rela­tionship between preparedcrown shoulder orcavity margin and the interproximal alveolarbone. At the same time, the other sides of thesame tooth, whose relationship with the bonewas normal to begin with, are ext rudedtogether with their ad jacent alveolar bone .Thi s genera tes excess ive bone in the latterareas, extend ing more coro nally th an is nor­mallv seen, which sometimes needs to beredu'u >d by periodontal / periosteal surgery.

It has been shown by Ingbe r (1974) and byStern and Becker (1980) that , in contrast withextrusive movement, tee th that u ndergo roo tupright ing and torqu eing movemen ts end u pwith a s igni ficantly lower crestal bone levelthan un treated controls, and the histogram inFig. 6.22 shows the in fluence of the variouscombinations of conse rva tive-versus -radicalsu rgical exposure and extrusion! tipping­versus- root mo vement orthod ontic forces onthe rela tive bone su pport of these teeth. Theseresu lts arc an ind ication of the periodont alprognosis of the teeth con cerned .

One last factor, which is often ignored orsimply overlooked , relates to roo t resorpti onthat ma y occu r in the impacted tooth duringthe extende d period of time th at may often beinvolved in its alig nm ent. In orthodontic trea t­ment, generally. resorption of the roo t ap icesof teeth may sometimes be seen . The rea sonsfor th is occurrence are no t d ear, althou ghrecent evidence has linked thvroid hormonewi th the phen omenon (Lobergand Engstrom,1994; Pou mparos et al, 1994). Nevertheless,there is no kno wn key that may be used to

PALATALLY IMPACTED CANINES

may be ob tained. However, unusually severeresorption may account for a final root lengthof, say, 12 01 01 . The same 2 01 01 d ifference inheight betwee n crcsral bone and CEJ will givea relative bone support in this pa tien t of on ly83% an d the long-term prognosis mus t bejudged accordingly. Thus for cases in wh ichthere is a more compromised bone loss in thecervical area, with a greater CEHo-cresta l­bone height d ifference, the relative impor­tance of root resorption as a facto r inlong-term tooth survival increases.

Mon itoring for early ind ications of rootresorption may be performed during theprogress of the mechanothe rap y of a givenImpacted canine, using peri apical radio-­graphs. However, since the pos ition of thetooth is changing during the procedure, com­parison with earlier films may be difficult. Itshould also be remembered that, even whenmarked resorption is noticed , it is un likelythat the or thod ontic treatment will be stop­ped much befo re full eruption has beenaccom plished . Less wou ld render the canineva lueless for all practical purposes and underanv circumstances.

The efficacy of radiographic monitoring isonly relevant a t the point whe n the crown ofthe tooth has been brought into its place inthe arch and a decision has to be madewhether root upright ing and torquetng move­men ts are desirable. If a periap ical radiogra phtaken at this juncture sho ws that significantresorption is evident, its severity must be off­set against the relative importance of produc­ing these roo t mo vemen ts.

A CLASSIFICATION OF PALATALLYIMPACTED CANINES

We have concluded that

(a) surgical traum a is grea ter when access isdiff icult , an d

(b) or thodon tic alignment is more complexwhe n the impacted tooth has a greaterdis pla cemen t. pa rticularl y if the root apexis not in the line of the a rch.

Yet it is these two factors, both of whi ch relateto the position of the tooth, that will later

dictate the qua lity of the su pporting structuresof the treated result. Accordingly, it becomesclear that the pa tient's best interests are servedif an accurate visualization of the exact loca­tion of the buried tooth is made at the outset,at the time of treatmen t plann ing. It followstha t if palatal canines arc class ified in relationto their pos ition in the maxilla then they willesse ntially be grou ped in accordance with theprognosis of their therapeutic outcome.

The classifica tion tha t is offered here isbased on two va riables:

(a) the transverse relat ionship of the crownof the tooth to the line of the dental arch,wh ich may be close or distant (nearer themidline);

(b) the height of the crown of the tooth inrelati on to the occlusal plane, wh ich maybe defined as high or low .

Determination of the location of the crown ofthe impacted tooth is achieved by employingthe rad iogra ph ic methods that we ha ve ou t­lined earlier. This positional determinationmay be subsequently confirmed by directvision at the time of su rgical exposure.

In this section, several cases will be pre­sented to illustra te the salien t clinical featu resof the impacted canines in each of the classifi­cat ion groups. An approach to treatmen t willbe discussed with in each group, and how thisneeds to be ad apted to suit the conditionsseen in each. Where re levant, cases that weretreated inappropriately will also be pre­sented, with the aim of revealing how thesho rtcomings of the results occur red and todiscuss wha t alternatives could have beenemployed to prevent the und esired sequelae .

Group 1

• Proximity to line of a rch: close• Position in maxilla: low

Typica lly, pa latal canines that arc close to theline of the arch and low in the maxilla suggesta good prognosis, insofar as the too th is usuallypalpable in the palate and read ily accessible tosurgery (Fig. 6.23). In its simp lest fonn, the

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH116_ _ _ _ _ _ _ _ _ _ _ _ "-'------'--__"-'---.c-.--:..-----'---'--_

(. j (b)

«) (dj

(e) (I)

Figure 1>.23

(a.b) Int ra-o ra l \Iil'w~ of the initial condition. (c) Space was "pcncd using .\ coil spr ing ,lIld slidi ng mechanics. An over­sited stilin1css s t<.'Cl tube is c u i to measu re, cu rved and pl,lc('d un tlw ar chwirc to maintain space and to increase basearch rigidi ty. (d) EXpOSUTl' and ,1 tl,lch mcn l bonding. Th e piglilil ligature is d raw n downward an d Loha ped over thearchw trc to allow for rvapproximotion of flap without impingement. Traction W ,15 applied immed iately. (e) Two wl'Cksposl -surgl'ry, .1 new 'slingsh" t' d ,lst ic module is stretched bet ween the bra ckets of the [.l ll'r.,l incisor and first premolar.Its middle po rti,'" is r,I;.......l to ~'ng,' ge the pigtail hook with il cont rolled and measurable light extru sive force. (f,g) Threemonths P'I'st-surgl.'ry . An inferior ly and la terally of~t light wire arc h is substituted, and the tooth ligated with s teel lig­atu .... wirl' to .lchil'\"~· fullnuption . An or thodontic bra cket no w rep laces the eyelet. (h,i) The gingival appearance showscomparable gingivallevels on the treated versus the un treated side. (j.k) Periapi ca l view, showing comparable support­ing bone levels in the treat ed and untreated cani nes.

PALATAllY IMPACTED CANINES

(fi gure b.D continued )

' .

(h)

(i)

canine is op posi te the space and is not rotated .The root apex is usually in its correct locat ionand root movements are rarel y necessary.

Surgery

Approached from the occluso-buccal (Fig.6.23d), little bone removal is needed to reachthe canine . Alte rnatively, following the reflec­tion of a palatal flap, the canine is immed i­ately obvious under its bu lging bu t thincovering of bone, on the inner su rface of thealveolar ridge. Minimal removal of eggshell­th in bone is needed to reach the follicular sac,

(k )

and access for bonding an attachm ent to thetooth is good. After resuturing of the full flap,the p igtai l ligatu re is drawn throu gh thesutured ed ge in the direction of the ma inarchwl re.

Planning the orthodontic strategy

With the too th immed iately opposite its placein the arch, o rthodont ic al ignm ent req uiressome extrusion, bu t principally a bu cca l tip­ping movement. Thus direct force applicationbet ween pigtail and archwire is the mostappropriate (Fig. 6.23e).

116

Problems that may be encountered

In the simples t group 1 case, the eye let mayoften be sufficient to complete aU the move­ments req uired. Alt ern atively, an d if surgeryhas exposed a su fficiently long clinical cro wn,a conventiona l bracket may be placed imme­d iately. However, it should be rememberedthat, L; the too th moves buccally, it gathe-sgingival tissue ahead of i t, an d, if ora lhygiene is not excellent, the ex uberant so ft tis­sue w ill become infla med an d may impi ngeon the b racket. Undoubtedly, wider exposu reo f the crown will eliminate th is, bu t will com­promise the periodontal tissues in th e finalanalysis. Thus it is wiser to use an eyele t ini­tially.

Complicat ions

Group 1 can ines, in their initial position s,ma y be com pl icated by rotation, m esialcrown d isp lacemen t or pa la tal root d isplace­me nt.

(a) Rotation. The type of rota tion tha t thecanine ge nerally p resents is a mes lo-Hngue lrotat ion, wit h the bu ccal surface of the too thfacin g mesially, toward s the root of the la te ralincisor. Th is mean s that, during treatment,the appliance must incorporate a rotationalmec hanism to bring the too th into align men t.The simp lest manner in wh ich to do th is is toin itially place the eyelet on the anatom iclab ial surface of the crown of the can ine,which faces anteriorly, towards the la teralincisor.

The ' slingshot' elastic is placed o r ela sticth read tied between the eye let and the cu tlength of stainl ess stee l tube (Fig. 6.23c) thathas been thr eaded on to the ma in archwi rc,for use as the canine space m aintainer and toad d rig idity to the base arch. While the canineis being mo ved towards the line of the arch, itis also bei ng rotated "bout its long axi s, in acorrective mesio-bu cca l ro ta tory movement.Since the sta inless stee l tube space maintainerwill not allow individual movement of thead jacent teeth, the di rection o f ro ta tion maybe changed O f increased to fit oth er type s ofrota ted pal a tal can ines, by tying the elastic

THEORTHODONTIC TREATMENT OF IMPACTED TEETH

thread from th e eyele t directly to the premo­lar or la teral inciso r tee th.

(b) M esial crOWII displacement. This is verycommonly seen in con jun ction wit h theme sio-llngua l ro ta tion th at we have jus tdescr ibed. Whet her or not the rota tion is pre­sent, the proximity of the anatomic labial su r­face of the canine to the la tera l incisor createsconstraints on the p lacing of a bracket at themidbuccal position o f the canine crown. As age neral rule, this space is too small for theplacement of any of the conventional b rack ­ets, which are so much bulkier. To ov ercometh is drawback, many p ractitione rs bo nd theconventiona l bracket, with its rigid and con­toured base, on the irregular palatal sur face ofthe tooth, to which it is totally unsu ited.

A fu rther d rawback is th at traction applieddirectly be tw een the bracket and the arch wirewill subst antia lly increase the ro ta tion of thetooth . Th is will be very d ifficu lt to co rrectla ter, and will sign ifican tly increase theamoun t of mechanotherapcu tic ma nipu lationthat the too th must undergo a-id the pe ri­odontal prognosis of the tooth will be com­p romised unnecessarily .

Traction from an eyelet placed in the idealmidbucca l position on the too th, even if it ismore incisally placed becau se of the ph ysica llimi tati ons imposed by the proximity of thela teral incisor, w ill bring about a correctiverota tional movemen t as the too th is d rawntow ard s the ta rget area. Pa la tal bracket-sitingrisks a complica tion (the de tach men t of theb racket), and while it solves one problem (theimpaction), it creates ano ther (increased rota­tion).

It is rela tively easy to bond an eyelet closeto the ideal mid bu ccal position of the exposedtooth and to d raw clastic thread from it to therigid tubing that has been pl aced on the arch­wire to maintain the canine space in the arch.It may be advantageous to tie the elasticthread to the bracket of the firs t premolar , toincrease the mesio-bu ccal rota tory compone nto f the traction. The premo lar w ill no t closed own the canine space, because of the pres­ence of the s ta inless s teel tubing. An extendedpe riod of tra ction will, however, s lowly b ringabou t ad ve rse changes in the dental mid line,

PALATALLY IMPACTED CANI NES

by tipping of the incisors in the light-wiretechniques, unless mesial uprighting springsare placed as 'brakes' on the incisors toincrease their anchorage value .

(c) Palatal root displacement. If the root apexof the canine is pal atally displaced, in addi­tion to the palatal crown displacement, thecrown will first need to be aligned in themanner that we have just described. Thisincludes the cor rection of any possible rota ­tion an d mesial crow n displacement. With thecanine crown in place and the main archwirefirmly ligated into the newly su bstitu ted, con­ventional bracket, the pal atally inclined longaxis of the tooth will d ictate that its palatalsurface bulges inferiorly, whil e the buccalsu rface tips superiorly.

The heavy archwire is now needed to serveas the base arch to a labial root-torquclngauxiliary . Employing a full rectang ular arch,which is torqued in stages on the canine on ly,the lon g-axis ind ination will be seen toimprove in time. At the same time, the rootsof the ad jacent teeth, which provide theancho rage for this di fficult movement, arethemselves being torqued lingually, at eachtorque-ad justing stage and then buccaUy asthe torqucing force is expended . Regardlessof the type of orthodontic bracke ts employed,there are advantages to using a torqueingauxiliary that derives its ancho rage from thenarrowed archform of the ma in archwi re.This will avoid disto rt ion of the denta l arch,and will not create unwanted ' round-trip­ping' movements of the adjacen t teeth.

Group 2

• Proximity to line of arch: close• Posit ion in maxilla: forward, low and

mesial to lateralincisor root

The root apex of the canine in this group isusually to be found in its correct place, in theline of the arch and at more or less the correc theight. The crown of the tooth, however, istilted mesially (forward) and in close assode-

tion with the palatal aspec t of the root of thelatera l incisor (Fig. 6.24) and often sitedbetween the roots of lateral and cen tra lincisors (Becker and Zilberman, t978). Thetooth is not always pa lpable on the pala talside. .

Surgery

Surgical expos ure in this group is compli­cated by the often unavoidable simultaneousexpos ure of the roots of these ad jacent teeth.Aggressive surg ical techniques may occasion­ally open the way for the or thodontist tobond on the labial surface, bu t no t wi thoutconsiderab le da mage to the adjacen t exposedincisor roo ls by the radical removal of bone.

With the position of the crown of theimpacted canine situated mesially to the rootof the lateral incisor, severa l operat ive prob­lems present themselves. In the first place,surgical expos ure has to be carefully under­taken, so as not to damage the roo ts of theincisors. The temptation to expose too Widelyshould be resisted, an d only enough of the

Figure 6.24

The periapical vicw of an extreme example of j.;roup 2can;J'Il.'S. Thl' 1l'f1 canine is located be tween lateral andcent ral incisor routs, and the right canine is mesial to thecen tral inciso r root.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH120 --"-:..::...--"-=====.:...=--"-.:...===~

most conveniently accessible su rface of thetoo th should be uncovered, to permit bond­ing. The palatal surgical flap should bereplaced in its entirety, in order to providemax imum protection for the exposed inciso rroots and the area of exposed bone, and to re­establish a no rm al periodontium. However,to p rov ide an exit fo r the tw isted ligatu re p ig­tail that is tied to the attachmen t, the flap isdivided into two halves by a slit that is madew ith an electrocautery. ra ther than a scalpel,in order to p reven t bleed ing at the cu tedge. The pigtail is passed through the slit,and the two-part flap is sutured back intoplace. Alternatively, the p igt ail ligatu re mustbe carefully passed through a small hole (Fig.6.25) punctured into the flap, which is noteasy to per form under these circums tan ces.

The mesic-pala ta! rotation of the caninethat is usuall y p resent in these cases placesthe labi al su rface of the canine in a com pletelyinaccessible position . Th is mean s that onlythe palatal aspect of the cani ne is availab le fo rsiting the attachment.

Planning the orthodontic strategy

From an eyelet p laced on the pal atal side ofthe tooth, direct traction to the labial ar chwireis sometimes possible . However, if traction is

Figu re 6.25

111f.' flap is fully sutured back 10 its place, and the steelpigta il may be seen 10 emerge Ihl'01Jgh a needle-piercedhole in the flap.

pe rformed in this manne r, the attached su r­face leads the way, and it will inevitablycause the canine to ' roll' over the root of thelateral incisor, to increase the exisiting rota­tion (Fig. 6.26). Once the too th reaches thearchwire, the operator cou ld be faced with al SOO rotation to pe rform! Few will di sputethat this task is very form id able, but, beforethe ad venturous clinicia n even begins toargue that it is not an im possible stu mblingblock, the following th ree qu estions sho uld beconsidered . How long will the de-rota tionpro long the appliance therapy? Will the rota­tional relapse factor be possible to overcome?Wh at w ill be the pred iction for the hea lth ofthe periodontium at the completion of correc­tion of the iatrogen ic ro tation?

For many of the im pacted teeth in group 2,the intimate relation between canine crownand latera l incisor root will block movemen tof the canine when d irect traction is applied .The inexperienced operator may thenres pond by increasing the p ressu re applied tothe too th, and, within a fairly short pe riod oftime, there will be signs of loss of anchorageon the othe r teeth, characterized by the p ro­duction of a crossbite tendency and a m idlineshift from the affected side, not to men tionthe possibi lity o f damage to the latera l inciso rroot.

A completely di fferen t approach must beused, in which the tooth must firs t be movedin a d ifferent d irection to free it from itsentanglement with the incisor roo ts. The mos tpractical m anner of doing this is to d ra w itvertically dow nwards (towards the tongue),erup ting it into the palate, in an exerciseaimed at converting the impaction into agr oup 1 case. It m ay then be moved directlyacross the line of the arch, towar ds the lab ialarchwire, in a second movement.

Three types of spring auxiliary may beused to bring about the desired movementthat is needed initially, in this first stage of theresolution. These are the ba llista (Jacoby,1979), the active palatal arc h (Becker andZilberman, 1975, 1978) and the ligh t auxiliarylabial ar ch (Kornhauser et el, 1996). In each ofthese meth od s, it is essential that a heavy basearch be tied into the brackets of all the tee thon the labial side, the aim being to hold the

PALATALLY IMPACTED CANINES

(.)

« )

opened space for the canine in the arch, toresist secondary distortion of the occlusalplane and archform, and to provide a basefrom whi ch to apply the force to the tooth.

The hollista (Figs 6.27a,b) is a un ilate ralspring of rectangu lar wire, wh ich is tied intoone of the rectangular molar tubes. It pro­ceeds forwa rds until it is opposite the can inespace. At this point, it is bent vertically do wn­ward s and terminates in a small loop. Withlight finge r pressure, the ver tical portion isturned upwards, across the can ine space, andtied into the pigtail ligature to lie close to thepalata l mucosa. In this way, torque is intro­duced into the ho rizon tal par t of the ballista,which is resisted to a great extent by themolar .

The elasticity of the ba llista spri ng exert spressure for it to return to its original verticalposition, wh ich, in tum, applies extrusive

figure 6.26

(a) A group 3 canine has been exposed , and hea ling is bysecondary inten tion (!). (b) An ed gewise bracket (!) hasbeen sited on the pa latal aspect of the cani ne. The tooth isbeing drawn from its pa lata l attach ment directly to a flex­ible labial archwire (! ). (c ) The too th has reached the arch­wire, and is now rotated a further 3O-4OQ

• Note theswollen appea rance of the gingivae and its poor contour.

force to the uneru pted toot h. If the impactedtooth is fairly resis tant to movement or if thedistance that the tooth needs to be moved isgreat, lingual molar roo t torque may occur,representing a loss of anchorage. To over­come this, a rectan gular main arch or a sol­de red pa lat al arch may be used .

The active palatal arch (Fig. 6.28a) consists of afine 0.020" removable palata l archwirc, car ry­ing an omega loop on each side. The wire isdou bled over at its extremity, to allow it to fric­tion-fit into a soldered horizontal 0.040" tubeon the palatal side of the maxillary molars. It isfur ther secured by a steel ligature tie and dis­tanced from the palate by gentle finger pres­sure. By elevatin g the downward-activatedpalatal archwire (Fig. 6.28b) and hooking thepigtail ligatu re around it , the unerupted toothcomes to be eru pted through the pa latal tissue,in a direction sligh tly away from the teeth.

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH122________ ____'--"-'----'-'-C --=-----=--- __=___~

(.)

(h)

Fig ure 6.27

(a) The ball ist.l in its p.lssive mod e, pointing downwards. (b) Using light finger pressure, thl.' loo pt.->d end of the spring isturned inwards and upw ards towards the palate, when ' it is latched in to the stamless s tee l pigta il fro m the uneruptedcan ine.

The auxi liary labial wire is a third possibility(Fig. 6.29); it requi res no ad vance preparationof any so rt, such as the soldering of lingualtubes. It is most conven iently fashioned froman archform blank of 0.014" d iam eter roundwire by forming a vertical loop in the area ofthe impacted canine. Th is loop has a sma lltermi nal helix. The auxiliary is tied into all thebrackets of the arch, in 'p iggyback' style, with

the extremities slotted into a spare tu be on themo lars, or left fret' d istal to the second prem o­lars. In a simila r manner to the ballista. thevertical loop is activated by pressing it pal­atally , across the canine sp ace, and ensnaringit in the pigtail ligaturc in the pal ate .

Thi s is a pa rticularly useful method for uscwith a bila teral im paction, when two d ifferen tloops will need to be inser ted into the arch-

PALATALLY IMPACTED CANINES

[a) (b)

Figure 6.28

(al The active palatal arch in if!; passive mode, lying several rrullimetres inferior to the pala te and ~'n from the occlusal.(b) The s-ame \'iew after the active palatal arch has bee n gen tly raised towards the palate and ensnared by the pigtailhooks, tbe rcby applying vertically extrusive traction to the unseen canines.

form. Used w ithout a base ar ch (Proffit, 1992;Kokich and Mathews, 1993), it will extrudethe adjacent tee th and thereby alter theocclusal plane. It will move the mola rs bu c­cally, and add itionally it w ill alter the hori­zonta l archform in the incisor area.

A mandibular rCII/ot'Ob1£' ap~'liance representsa method that requires no maxillary applianceat all, in the first instance (Orton et al, 1995).Vertic al extrusive force is derived from aremovable appliance in the opposing jaw,throu gh the agency of a latex elastic. This clas­tic is applied by the patient between the claspsof the mand ibu lar appliance and the pigtailliga ture in the palate. A maxillary orthodonticappliance is needed only when the tooth haserupted through the palatal mucosa .

Rega rd less of wh ich met hod is employe d,the successfu l end-resul t will find the newlyerupted tooth, su rro unded by a wide rim ofpalatal mucosa and bone, in the middle of thepalate (Fig. 6.30). The more the tooth iserupted , the easier it will be to pla ce anattachment on its buccal sur face to enable thetooth to be moved bu ccally, without thebracket 'im pinging on the g ingiva . However,an excessively erupted tooth will lead to

occlusal trauma as it moves across the line ofmandibu lar tee th .

For the first stage of the two-stage manoeu­vre, the position of the eyelet is immaterial.Therefore bond ing is performed to the mos tconvenient surface available, since no ad verserotation of the too th will occur whi le it isbeing moved vertically downwards. Thetooth is cleared of the latera l incisor roo t andmoved until it has an unobst ructed path tothe archwire. A second eyelet is bonded to thetooth , this time on the mid buccal aspect,which will ha ve become accessible as theresult of the initi al orthodo nt ic movement.The second stage of traction may then com­mence, with the application of force from thesecond eyelet di rectly to the labia l archwire.

The poin t shou ld be mode tha t in this case.and in any othe r group or situation, directtrac tion to the archwlrc shou ld on ly bepe rformed from an atta chment sited in themidbuccal position of the tooth . Tractionapplied at an y ot her site w ill engender anunwa nted rotation as the too th progressestowards its p lace in the ar ch - a rotation thatwill requ ire cor rection in an ex tra and super­fluous phase of orthod ontics.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH124---- - ----- ----------- -

(4)

(b)

(d)

«)

Figure 6.29

(a) lnitinltreatment has created space, and a heavy basearch ca rry ing a stainless st ee l tu be space m ainta iner is inplace. (b) A typical auxiliary labial archwirc of 0.014"gau ge with its vertical loop and terminal helix. (c) Theauxiliary labia l archwire is tied or pin ned into the brack­ets 'pimback' over the heavy base arch, immt'd iatelyprior to surgical exposure. (d) Following the full flap clo­sure, the vertic al loop is gently turned inwards andupwards, with us helix secured inlo the terminal hoo k ofthe piglaiL This is the same case as in Fig. 6.25.

PALATALLY IMPACTED CANINES

FigUll! 6..30

The tooth has eru pted ap propriately, and is ready for itsbuccal traction .

Problems that may be encountered

On occasion, the palatal tissue is very res is­tan t and bu lges more and more as the toothprogresses, bu t does no t allow the tooth toerupt (Fig. 6.31d). This eventua lity w ill neces­sitate a very limited and superficial su rgicalremoval o f the th ick mucosa immediatelyover the crown of the tooth. The anteriorpalatine artery is located in this im med iatearea, an d care should be taken not to sever it,in w ha t is otherwise a very simple procedure.

Once the tooth is we ll er upted, at the levelof the occlusa l plane, a new eyelet attachmentis bond ed to its anatomically buccal sur face(Fig. 6.31e). It is then drawn in a di rect line tothe labial archwire and to the place wherespace will have been provided for it in the ini­tial or thodon tic phase of the treatment. Initia lrotation of the can ine w ill s till be presentwhen th is second phase of the traction beg ins,bu t it will cor rec t steadily as the traction pro­ceeds, with the attachment and buccal sur faceleading the way.

Even with good oral hygiene during thetrac tio n period , mu ch exuberant gingival tis­sue precedes the canine during its m igra tiontowards the line o f the ar ch. The prematureuse of a con ven tional bracket may res ult intissue impingemen t, pa rticu larly as the tooth

125

comes in to close relation w ith the ad jacen tteeth . The orthodont is t should not relinquishthe use o f the eye let until no furthe r buccalmovement is needed .

Co mp licat ions

The in itial location of the too th may be com­plicated by one or both of the following con­d itions.

(a) Rotation. As w ith the g roup 1 canine, ames ic-l ingual rotat ion is common, and itis largely corrected during the seco ndstage of resolution. when traction is madefrom the second eyelet, on the bu ccal sur­face of the tooth.

(b) Palatally displaced root. Occa sionally atooth in thi s group may p resent with theroot palatally d isplaced , in addi tion to thecrown (i.e. a palatal translation of theentire tooth). Its occurren ce will compli­cate the appliance work by requiri ng theintro d uction of buccal root to rque andoften some mesio-di stal root uprighting.These forces may onl y be applied oncethe crown has been en gaged by the mainlab ial arch wire.

H will be app rec iated that a group 2 can ineha s to be approached with a good measure o fp reparedness. From the su rgical point of view,access is not d ifficult, but exposure must beperformed carefully 10 avoid damaging thead jacent teet h. The orthodontic appliance mayneed to execu te as many as five different typesof mov ement, involving both crown tippingand roo t movement, i.e. ver tical extrusionfrom the palate, buccal tipping to the line ofthe arch, ro tat ion, mesio-di stal root uprigh tingand buccal root torque. From the periodontalpo int of view, the prognosis of the resu lt isdependent on the smooth executi on of the sur­gical and orthodontic opera tive proced ures.Mism anagement o f both the orthodontic andthe surgical s tages may not be germane to thequestion of whether the final alignmen t of thetooth will be technically successful, but it willbe critical in determ ining the final bone level(Figs 6.31j,k ) and periodon tal cond ition thatmay be ach ieved (Figs 6.31g,h ).

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH126----------------------

C,j (h)

(ej (d)

Figu re &.31

(a) A group 2. ra nine in ,1 tz-ycar -otd f('malt' has been minimally exposed on its palatal aide. The tip of the cusp has notbeen exposed. An eyelet attachment has been bon ded to. the palatal side. (b) Suturing is completed, with the pigtaill'meq; inlllhruugh the divided nap . The palatal arch is prepared for ligat ion. (e) The palatal arch fu lly tied-in and active .(d ) Seen 3 month s later, afte r two in tervening visits for adjustment, the archwir e has bec ome distanced frum the palate ,and the canine can be S,'(' O to bu lge ttll' contour of the palate almost to tht' occlusallevel. (el The decid uous canine wast'xlr,ld l'd .11 th... sa me time .1S the minim al re-expcs urc was performed, prepa rlltory to buccal movement. A sec ond eye­let is bon ded sllghtly mesi,11 to the mid-buccal position, and elastic ligation is drawing the tooth d irectly to the archwire.wttha favou rable rotJt ioll vector from the sec ond eyelet . ( f) At 13 months pos t-surgery , the C,111ine is in the orch, and abr,lC~et is subst ituted for the eyelet. (g. h ) The gingival hea lth of the treated canine b good, but its clinical crown islonger than lh, ' unt reatedleft canine. (i) Th,' pe riapical view. Noll,' the re irbed mo t ,1"".')< of riKhtlat" fal inciso r. (j. k)Post-treatmen t p•.'ri" pic,11 vi,'ws to show comparable bone sup port of treat e l and un treated canines.

PALATALLY IMPACTED CAN INES

IFigurt> 6.31 ro"tillUed )

«(') If)

(g)

•

I

(i) (k)

126

Group 3

• Proximity to line of arch: close• Pos ition in max illa: h igh

The roo t a pex of the can ine in th is group issitua ted ve ry h igh in the maxilla, althoughmo st often in the general, bucco-llngual, lineof the arch and in its correct location in theantero-posterior plane . The crown is high andonly relatively mildly displa ced palatally, andit is no t usua lly palpab le .

Surg ical and orthodontic strategy

Access to this tooth may be eithe r fro m thebuccal side or from th~ palata l side, w ithadvantages and disadvantages to bothapproaches, since there is a s ignificant thick­ness of bone medial and lateral to the tooth .Consi derable bone removal is needed to reachit from either side, with s imila r d ifficulty inthe applicat ion of an attachment. The o rtho­dontic t reatment entailed in align ing such atooth involves principally extrusion, togetherwith a bu ccal tipping movem ent.

The buccal approach

From the bu ccal side, the tooth is approa chedas for a buccal impaction, which was describedin Chapter 3. The surgeon may have grea terdifficulty in locating the im pacted tooth, andwill be more depe ndent on the radiographs.

The apically repositioned flap (Vanarsdall andCom , 1977) woul d, a t firs t s ight, appear to bea go od approa ch, since it offers su itableaccess for the ap p lication of orthodontic forced irect to the archwtre. It also en sures tha t anadequate band of atta ched gingiva be raisedabove the level of the impacted tooth andthe n accompany that too th in its subsequentd ownward path .

From the su rgical poin t o f view, ho wever,this approach takes no account of the three­dimensional locati on of the canine . Themethod mav be very suitable for a buccalcanine who~ vertical d isplacemen t is rela­tively mi nor, bu t in the case of a mo re su peri­orly displaced pal atal canine this type ofexposure wou ld leave a con siderab le expanse

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

of alveolar bone open to the oral environmentand the flap su tu red several millimetreslateral to the crown o f the tooth. Furthermore,the maintenance of the exposure of a caninecrown, palatal to the line of the arch, wou ldsecondarily cause a d enu d ing of the inter­p rox imal areas of the roo ts o f the ad jacentlat eral inc isor and firs t premolar tee th . Thismethod is on ly su ita ble for cases of ve ryminor palatal di splacement.

Fil II flap reflection and its subsequ ent pa rtia lreplacement over the exposed too th, togetherwith the placemen t of a su rgical pack, hasbee n used for man y years, and was widelyadvocated (Lappin, 1951; Johnston, 1969;Lewis, 1971; von dcr Heyd t, 1975) for apalatally impacted canine. In the case of agroup 3 canine, a considerable thickness ofalveola r bone is present both inferiorly andinfer io-buccel ly to the canine, which must betraversed by the too th . In ord er to overcomethis physical im ped imen t, the above aut ho rsh ave recommend ed the surgical cha nnellingo f bone, to free a path in the d irection of thedental arch (Figs 6.32a-e ).

Experience with this procedure shows th at,while it lives up to its expectations regard ingthe p rovision of access and the enab lemcnt ofd irect traction, it d oc'S so only by the p lannedsacrifice of much of the bone of the immed iatearea of the alveola r p rocess! The treated resu lt(Fig. 6.32d ) then leaves an aligned caninewith an unacceptably reduced bone su pportand a m uch poorer periodontal prognosisthan cou ld be achieved by other mean s.

The tunnel approach

An excellent modification of th is method h asrecently been de scribed (Crcsd ru ct al, 1994) inwhich the buccal plate of bon e is preserved,while the im pacted tooth is d rawn through atu nnel in the bo ne provided by the vacatedsocket of the simultaneously extracted decidu­ous canine (Fig. 6.33a). The same full flap isreflected an d the impacted too th exposed,leaving the buccal plate in ferior to it intact. Thedeciduous canine is extracted, and its socket isextended and w idened su fficiently to allow thepassage of a fine wire th rough it as far as theimpacted tooth.

PALATALLY IMPACTEDCANINES

(.j

« j

(bj

(dj

Figure 6.32

(a.b ) The grou p 3 canine has been exposed from the buccal side, and bone has been channelled to clear a direct pa th tothe archwirc. (c) With the band cemented to the canine, the radical nature (If the surgery may be seen. (d) The ,lligm'dcanine shows a long clinical crown and a lack of normal bony contou r. Note the deficient interdental papillae.

130

,.j

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(b j

,<jFigure 6.JJ

(a) The ' tunnel' approach. NOlt' the pn..'SI.'rva tion of the buccal plate in terior to the too th . The stainless steel pigtail isd rawn inferio rly through the vacated sock..t of the deciduous canine. (b) At 2.5 mo nths posl-su rgt' ry, Ike "slingshot'elas tic module has brought the (aninI.' into d buccally palapable posi tion. (c ) 1 ymr after comp letion of treatmen t. Notethe gingival h..ight, wide attached gingiva an d good bo ny con tou r.

An eyelet att achment on steel mesh isthreaded with 0.011" soft ligature wire , readyfor bond ing to the newly exposed impactedcanine. Following appropr iate acid etching ofthe enamel surface, the attach ment is load edwith the bonding ag en t, and its s teel liga turep igtail is lightly curved an d threaded into theim media te area of the exposed too th and oninto the p repa red tunnel un til it emerges fromthe occlusal end o f the deciduous caninesocket. At this point. the eye let att achmen t ispressed firmly into place on the impactedtooth.

The surgical flap is resu tured to its fo rmerp lace, and visua l contact wit h the impactedtooth is los t. Contro l of fu ture m ovemen t ofthe canine is exercised thro ugh the ap plica­tion of force to the steel pigtail ligatu re,whose ex trem ity may be seen to extendth rough the sutu red edges o f the flap. w ith inthe decid uo us canine socket. Any excess in itslength is cut, and it is fashioned in to a smallh ook, to which ela sti c tract ion may beapplied .

The su rgical method affords good access tothe canine and a minor degree of difficulty in

PALATAllY IMPACTED CANINES

threading the ligature. Or thodontic tractionmay be efficiently applied, an d the treatmentresult shows a good bony profile and anun compromiscd pe riodon tal resu lt, similar tothat seen on normally erupted teeth (Cresciruc t al, 1994 ).

' . .. ..:~.e.;;...

The palatal approach

With the crown of the canine slightly mo repalatally d isplaced, su rgery on the buccalside needs to become more radical, renderinga palatal approach preferable.

Following the ra ising of a palatal flap, thecan ine will be revealed high up, pal atal to theroots of the adjacen t teeth, wh ich occasionallymay themselves become denuded in theprocess. Infer ior and lateral to the can ine isthe vertical wa ll of the alveola r process.Bonding of the eyelet attachment is per­fo rmed in the usua l ma nner, to the most con­ven iently accessible site, which is the palatalside of the too th, although the buccal surface,d ose to the tip, is occasionally poss ible.

In this situa tion, many su rgeo ns willremove a part of the flap in order to leavethe impacted tooth in visual cont act with theexterior and will place a pack to cover theopen area . If the sta inless steel pigtail ligatureis drawn towards the line of the arch andsutured into place so that its extremity comesthrough the deficien t pa rt of the flap, theapplication of or thodontic forces will give riseto significant danger of irr itation and infec­tion of the area. This is caused by the too thbeing drawn buccally and vertically down­wards by its ligation to the labial arch­wire.T he resul tant direct ion of this force willcause the impacted canine to be draw n late r­ally against the alveolus and its healing gra n­ula tion tissue. The exposed tooth will becom ereburied in these tissues (Fig. 6.34) as it pro­ceeds do wnwards and buccally. This leads toinflammat ion, false pocketing and the likelyoccurrence of an acute lateral pe riodontalabscess.

It is therefo re advised that ort hodonticstra tegy for group 3 canine..'S be altered, bydividing its reso lu tion into two distinctstages , as wit h gro up 2 canines (Fig. 6.35).

Figure 6..34

Direc t traction Wf5US two-stage tracti on in tho! grou p 3

canine .

Orthodon tic traction is first applied in the lin­gua l and vert ically downward di rection, toerupt the tooth into the palate, palatal to theline of the arch and brought down to theocclusal leve l. As it comes down, it is accom­panied by a wide collar of newly formed alve­olar bone.

At this po int, an ad d itiona l eyelet sho uldthen be pla ced on the buccal aspect, as fo r agroup 2 case, and the direction of tractionaltered to a pu re buccal tipping movemen t, tobring it into the arch. It is often possible tobond a conventional bracket to complete this

(bj

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH

' oj

Figure 6.35

(a) A group 3 canin\' t·xpoSl..od and viewed from the occlusal aspect to show the attachment bonded nc ar the tip of thebuccal side. (h ) six weeks later ,10<.1 without fu rther adjustment. the canine has erupted through the closed flap. (c)Buccaltraction to the buccally placed eyelet. (d.e) The bucca l and palatal views of gingival tissues on the treated side, 16months post-surgery. (f,g) The same views of the nonnal side. (h.i) Periapical views of the treated (right) and un treatedsides, showing comparable bo ne suppo rt levels .

PALATAllY IMPACTED CANINES

(Figure 6.35 am/i,wM )

Cd' (.)

cn

Ch'

/"

(i)

(g)

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH'34 - - - - - - - - - - - - - --- - - - - - -secon d stage if the re is enough gingi va l clea r­ance on the buccal su rface of the too th ,althoug h this m,1y not be necessary. Since nei­ther rota tion no r ectopic root apex position iscommon in these cases, the second-stage tip­ping movement ge ne rally brings the caninein to its desi rabl e position and inclina tion.

The canine that is loca ted in the positionthat we hav e d escr ibed here p rese nts di ffer ­en t problems from the grou p 2 CiISCS. Directtraction is, u nder these circu mstances, techni­cally possible, but per iod on tally hazardous.The mos t d irect sur gical remed y (from thebuccal side) is too rad ical a nd leaves thetoo th relatively unsupported by bone, in thefinal analysis, unless the ' tunnel' approach(Cresc ini et el, 1994) is used. However, forthe palata l approach, careful two-stage ortho­dontic mo vement will req u ire minimalsurgery and avoid u ndesirab le periodonta lsequ elae.

The principal feature th at di s tingu ishes thegroup 3 case from the simp le and s traigh tfor­ward group 1 case is its rela tive height in thealveolus. The roo t apex is usu all y in the lineof the arch, and the crown is only relativelyminima lly d isp laced palatally, which of tenmeans that the too th cannot be pa lpated. Thegroup 1 ca nine req u ires a minimal degree ofver tical developmen t in the mechanotherapy,an d m ainly a bu ccal tip ping movement fromits more severe pa latal position. The group 3canine, on the other hand , has primarily to beextru ded ve rtically. If only a very mino r buc­cal component is needed then a bucca l at>"p reach to sur gery, using th e ' tu nnel' method ,may sometimes be ad vantageous.

Group 4

• Proximity to line of arch: d istant• Position in max illa: high

Whe n the crown of the palatally d isplacedcanine is not di rectly rela ted to the roo ts ofthe incisors, it generally po in ts medially andapp roaches or even crosses the mid -pala ta lsuture (Fig. 6.36). It is not always palpable inthe pa la te.

Surgery

These teeth arc generally at some d is tancefrom the ad jacent teeth, and little boneremoval is needed to expose them, with scantd anger of exposing the roots of other teeth .Th ere is us u ally reasona bly good access forthe placement of a bond ed atta chment, al­though the immed iate exposed su rface isunlikely to be the b ucca l as pect of the tooth .

Planning the orthod ontic strategy

Since there is no rmal positioning o f the roo tapex in most of these cases, all tha t wou ldappear necessary is to draw the tooth d irectlyto the labial archwire. If the long axis of thetoo th is dose to the horizontal plane, it wouldbe ina ppropriate to do this, s ince the directionof this force would be virtua lly coincidentwith its long ax is. This makes the mechanicshighly ine fficient, and lit tle progress inrt..'Solving the impaction will be seen. Theproced u re will become excessively taxingon anchorage, an d will give rise to n rcac­nvc movement of the entire maxillary d enti­tion.

With the too th close to the horizon tal, amo re cautious approach should be embarkedupon. A wid e downward tipping movementw ill be achieved more efficiently with thesame vertical directional ap proach that hasbeen described for use in group 2 an d 3 cases,with the use of sprin g aux iliaries .

Were the fulcrum for this wid e tipp ingmovemen t of the canine to be at the roo t end,then it would follow that the root apex posi­tion would be u nchanged when the cro wnfinal ly reach ed its d estination in the line ofthe arch. Un fort unately, however , the ful­cru m is us ua lly some sho r t way along the ap i­ca l portion of the roo t, and therefore , d u ringthe alignment of the too th, there will be a co n­co mt ttant palatal d isplacement of the roo tapex of the canine . Thus some buccal roo ttorq ue of the group 4 canine will later be nec­essary. The refore it also follo ws th at in theunusual situa tion where there is a pa latal d is­placement of the root apex at the ou tse t,m uch torque will be req uired , and this pre­sents a major clin ica l pro blem .

PALATALLY IMPACTED CANINES

Problems

Torque canno t be applied until the crown ofthe tooth has reached its place in the arch andits conven tional orthodonti c bracket firml yengaged by the labial archwlre. At thatjuncture, the crown of the can ine is at theocclusa l level and has a st rong bucca l tilt.This places the pa latally d isplaced roo t lew inthe pa late, with its profile clea rly outlinedunder the mu coperiosteum. That cri ticalpo rtion of the lingual side of the roo t closestto the crow n of the canine has a marked lyconvex shape, which di ctate s a di stinctbulging of the mucosa cove ring it. In the clini­cal context, some dehiscence of this lingu alarea of the cemen ta -enamel junction is us u­ally present. Add itionally, the cingu lum areaof the palatal aspect of the crown is veryprominen t, and is likely to interfere with theocclus ion.

It is importa nt to recognize tha t in g roup4 cases and many group 2 cases, conside r­able lateral movement of the canine isrequired, most of which involves tipping.Quite freq uently, buccal root torque isalso needed, and this may be quite consider­able, particularly in the present group.Accord ingly, there is an equal an d oppositereactive force acting over a long period on theen tire a nchor unit, w hich, if properly plannedand prepared, w ill respond only minima lly.Th is w ill be expressed as a movement ofthe dental mid line to the o pposite side anda crossbite tendency on the sa me side. Inorder to minimize this, a heavy base archshould be used , and its for m should bealtered to com pensate for the expected move­ments. A bilaterally affected case prov ides theopportunity for nu llifying loss of anchorageby pitting one side against the other, suchthat mid line and arc hform alterations neednot occur.

To summarize the group 4 cases, the clini­cian must be alert to d ifficu lties in themecha nics that the location of the canine pro­vide. Ca re must be taken to preserve ortho­dontic anchorage by properly planning themechanotherapeutic stra tegy of reducing thecanine displacement. The practical limitationsImposed may lead to adverse effects on the

period ont ic sta tus o f the lingu al aspect ofthe tooth, where occlusal interference mav bepresent in the interim until the root position iscorrected .

Group S

• Can ine root apex mesial to that of late ralinciso r or d istal to tha t of firs t premolar.

This tooth should be considered as a trans­posed tooth. To be completely consis tent w iththe definition of transposition, the canineapex should be in the line of the arch, in theplace of the root apex of the adjacent tooth,but it is ind epende nt of mesio-d is tal or bucco­lingual crown location .

Surgery

Many of the transposed canines are at leas tpartially erupted, wh ich obviates the need forsu rgery. It is not possible to identify impac­tion trends among the remainder that mightsuggest a part icu lar approach to their expo­su re. Rather, each should be su rgicallyexposed in line with its own pa rticula rdemands and circu mstances. What is true isthat several of these may be so d isplaced tha tmod alities of treat ment other than orthcdon­tics should be considered, par ticu larly extra­tion and pros thetic replacement or, p referably,reten tion of the deci d uou s cani ne.

Planning the orthodontic s trategy

The canines in group 5 may be offered fourpossible lines of treatmen t that arc appropri­ate procedures for their resolu tion :

(a) to reso lve the transposition to the idealrelatio nship (Fig. 6.37);

(b) to move the premolar mesially (or incisord istally) into the can ine loca tion and alig nthe canine between the two premolarsmg. 6.38);

(c) to use the canine for auto tra nsplan tationinto a prepared socket in its ideal site; or

Cd) to ext ract the severely displaced canine,incisor or premolar, depe nding upon

THE ORTHODONTICTREATMENTOF IMPACTED TEETH136________ __'-'-------"'-"----'-'-'-----=--'-'------=e.-.=_

('J

(b)

,e' ,d,

Figure 6.36

(a] The active palata l arch in place to cru pt a group 4 caoinl' that has traversed the midline , (b) Post-su rgical peria pica lradiograph shows space opening and an active palatal arch ligated to the bonded attachment. (e) After 3 months of trac­tion. minimal re-exposure of the now Vl'ry superficial and palpable canine was pe rform ed . A poste rior componen t wasachieved using elastic thre ad to the lingual tube of the molar of that side. (d) tusec-bcccat followed by purely buccaltraction was also performed. Dista l up righting and buccal root torque were later need ed . (e, f) Intra-oral views to com­pare the buccal gingival health and clinical crown length of the treated (right) and untreated canines. (g..h) The same orothe palatal side.

PALATALLY IMPACTED CANINES

(Figure 6.36 co'IUmm l)

(h)

THE ORTHODONTIC TREATMENT OF IMPA CTED TEETH138- - - - - - - - --- - - - - - - - - - - -

(, )

( 0 )

(<I

Figu re 638

(a,b) Ca mne/Iateral inci"",r transposition see n inlra ­o ra lly and on pancrarmc radiograph. (e) The completedalig nment of the tee th in the tra nsposed order. G rind ingof the incisal edge of the lateral incisor need s to be pe r­formed to avoid occlusal interference an d to im provei1ppc.lrilna'.

Figu re 6.37

(",1:» A maxillary canine/ fi rst prem olar tr,m~p()s i tion, (b)treated 10 reverse the tran sposition .

w hich has the least chance to be alig nedwith a good p rognosis.

Mecha notherapy aimed at red ucing trans­position and bri nging the too th to its correctposition in the d ental arch is frau gh t with dif­flcul tv. Whether the crown of the canine isd rawn directly towards the labia l archwire oronly af teran initial ve rtic al tr action p hase, thecanine' s roo t will inev itably co me into d oserelation wi th the roo t of the adjacent first pre­mo lar or la teral incisor. Root contact in group5 cases creates a mechanical cou ple. The con­tinued ap plica tion of force fro m the labialarchwi re will d raw the crown o f the canineever closer, although wit h greater d ifficu ltyan d taking consid erably more time.

(b )

PALATALLY IMPACTED CAN INES

Prob lems that may be encountered

If we assume that the entire canine tooth ispalata l to the line of the arch, the secondaryeffect of the root contact will rotate thecanine's root apex, both mesially andpalata lly, across the palate, in a wid e sweep­ing movement. The toot h will become 1aidout' immed iately beneath the periosteum,an d the long profile of its root will be pa lpa ­ble under the palatal mu cosa. Dehiscence ofthe cervical area of the root surface will occur(Fig. 6.39). The amo unt of unavoidable labialroot torque tha t will then be required will beextreme and beyon d therapeutic reason. If thecan ine position is buccal to the root of thead jacent tooth and the tooth is brou ght buccalto the first premolar or the lateral incisor, fur­ther buccal d isplacement of its root will occur,with gross dehiscence of the buccal periodon­tium.

To achieve complete and ideal o rthodonticalignme nt of the gro up 5 canine, while mini­mizing these severe pe riodontal conse­quences, mechanotherapy would need to beaimed at both transposed teeth. The root ofone would need to be torqued in a lingualand then distal flanking movement, while theother would need to be torqued in an oppo­site buccal and mesial flank ing movement. Inthis way , neither would be displaced too far

Figure-6.39

A 1ilid-ou l' camne d Ol.' to contact of the canine wit h theroo t of the p remola r during traction. (Courtl'Sy ofDr Y be n a, .......1.)

from the line of the arch, and, whil e eachwou ld undoubted ly suffer pe r iod on tally, thiswould be less tha n than eithe r one ind ividu­ally. It wou ld be of grea t help if a practicalmethod could be devised to perform thesedifficult movements on an unerupted tooth,wh ile the crown is too distant to be ligatedinto the labial archwire.

While each of the above four trea tme nt pos­sib ilities will be recommended in specificins tances, it becomes clear that the most likelyand practical course will be to recognize andaccept the transposition . The canine should bebrought into the dental arch with the first andsecond premolars (or between central and lat­eral incisors) as its mesial an d dista l neigh­bours respectively.

'Macho ism' may be the driving force be­hind the decision to place the teeth in theircorrect order, since, after all, we are or tho­dontists and this is the sort of challenge forwhich we have been trained . It is d ifficult topass nver an opportunity to d isp lay our ini­tiative, our dexterity and our clinical excel­lence. Sometimes this is justified - but notoften.

It should always be remembered that thereversa l of a tran sposi tion dictates, of neces­sity , tha t the two teeth have to pass by oneanother in an alveolar process whose bucca­lingua l width is sui table for just one of them.True, when teeth are moved buccally or lin­gua lly on the ridge, there is a concomitantbucco-lingual expa nsion of the alveolar bone.Clinically, however, there is loss in boneheigh t, and a dehiscence may occur, particu­larly if oral hygie ne is inadequate. Fur ther­more, the bio mechanics is dif ficult to performwith adequate TOot con trol , an d root proxim­ity may occur du ring the exercise. This couldser iously compromise bone suppor t on thatsurface of the two roots, and some loss ofattachment or even roo t resorption mayoccur.

Group 6

• Erupting in the line of the arch, in pla ce ofand resorbing the roots of the incisors

THE ORTHODONTICTREATMENT OF IMPACTEDTEETH140________ _ ----'...:::..::...::c-'-=-'--'----=--:..~=_______'__.::=___==

Why uneru pted pe rmanen t tee th . which arein close proximity to the roots of their neigh­bours, cause resorp tion of the roots of neigh­bouring teeth is unclear. Ho wever, when itdoes happe n, it is aggressive and usuallynon-sym ptoma tic. The presence of follicu ­IarZdcntigerou s cysts, which may dis p lacethe root s of the ..adjacent teeth, is not generallyassociated with the ir resorp tion (Brill et al,1993a; Ericso n and Kurol. 1987a,b). However,root resorption of the lateral incis or is d iag­nosed far more frequently when this too th isof norma l size than when it is small or peg­shaped. In other words, in those cases thatshow the typical p icture of associa ted anom­alies described earlier in this chapter, the like­lihood that they will exhibit roo t resorption issmall (Brin ct ill, 1993a).

Given that th is type of resorption is rap id lyprogressive, d iag nosis and treatment deci­s ions must be made speed ily. The condi tioncons titu tes one of the very few situations inwhic h orthodontic trea tm en t may be con sid­ered a quasi-emergency.

Periapical radiography will help the clini­cian to diagnose and assess the degree ofexisting resorption , but p recision in determ in­ing the ang ula tion o f the tu be to the too th andthe film m.1Y be cri tical in these cases .Subsequen t radiographic follow-up of (a) thechanging posit ion of the canine, which isbeing elicited by the mechanotherapy, and (b)the progress of the resorption process is theonly practical method available to monitorthe resolution o f the problem. Accordingly,periapical radiographs , taken without regardto standa rd ization, \v i11 lead to the d rawing ofina ppropriate conclusions on bot h scores.

Lateral views of the <Interior Mea of th emaxilla (lateral cephalogram or tangentialview) may show the profile view of the longaxes of the canine and of the affected incisortee th to be conti nuous with one another.However, superimposition of other teeth isIikelv to make this view inconclusive. Thevertex occlusal view will confirm that thecanine is not di splaced buccally or palatally,and, given its overlapping relationship w iththe adjacent incisor, one m" y draw the con­clusion that roo t resorption is present andthat the cani ne is in the same bucco-lingual

and mesio-distal plane. In ord er to achievethe most definitive d iagnosis of the extent ofthe resorption and the position of the associ­ated canines, compu ted tomography (CTscann ing) will be of grea t help.

Accord ing to Ericson and Kurol 0 987b),resorp tion occurs more frequentl y in palatalcanine cases than is generally recor ded ornoti ced by the orthodon tist. This wouldappear to be due to the fact that many of thecases wit h mild pathology remain undt ag­nosed . However, these are not the cases thatbelong to group 6, since the resorp tionprocess in minor and su perficial areas of rootsu rface will generally cease to be active onceth e position of the canine has altered , and thelong-term prognosis o f the canine a nd thetooth exhibiting the resorption will no t beendangered. These cases may be more logi­cally and more conven ien tly p laced in othergroups, particu larly gro up 3.

Group 6 is reserved for those ca nines thatare associa ted with or have the po tential forsignifican t loss of root length of th e adjacen ttee th and that are actuall y erupting into thearea formerly occupied by the d isappearin groo t (Fig. 6.40). As such, they are not genet­ally palpable, since they are situated in thesame bucco-lingual plane as the incisors.

The root apex may be dose to its ideal posi­tio n, in the line of the arc h. However, theapcx--eusp orientation of the canine is alm ostinvariabl y dow nwa rds and mesially, wi th aslight med ial <towards the m idline) compo­nen t. Radiographic views showing the tip ofthe canine cusp loca ted agains t and withinthe resorbed d ista l side of the incisor roo t, arevery easy to recognize. This type of casereq uires di stal and buccal tipping of the toot htowards the archwi re, to d istance the two ele­men ts from their destructive entanglement.This moveme nt is easy to p roduce, once thesurgeon has exposed on ly the di stal pa rt ofthe tooth and an attachment has been placedon this surface.

The long axis of the toot h may be pointingobliquely across the incisor root, with the api­cal half having disappeared in the reso rp tionprocess. This may now have broug ht the tipof the cro wn within the former root area andclose to the area of resorp tive activity . Dis tal

PALATALLY IMPACTED CANINES

and buccal tipping of the tooth towards thearchwire is unsuitab le, since this alwaysinvolves some downward movement, whichwill aggravate the resorption of the more infe­riorly placed rem ainder of the root.

The unchecked advance of the canine maycause total reso rption and shed ding of one ormore of the incisors, and it will place thecanine in a finally erupted position, where itsap pearance is unacceptable and its use as aprosthetic ab utment is equally inappropriate,because of angu lation.

Su rge ry and the planning of orthodonticstrategy

Two possible escape rou tes are available toretrieve the crown of the canine from the area,in the effort to salvage as much of the incisoras possible, while improving the position ofthe canine and its prognosis.

The first route necessitates a pa latal surgicalapproach (Fig. 6.40) to place an attachment onthat aspec t of the tooth first exposed, ,v-ithextreme care being exercised not to extend theexposure furt her tha n is necessary in anydirection. Ort hodontic traction is then appliedto move the crown posteriorly in the horizon­tal plane, in a direct line toward s the maxillarymolars, without incorporat ing a vertical down­ward movement. In this way, the crown willfollow a poster ior and med ial circuitous pa tharound the fulcru m of its root apex. Once ithas erupted through the palatal mucosa, aneyelet is placed on its buccal aspect and thetooth may be safely drawn to the archwire.

The second route requires an exposure ofthe tooth from the buccal (Fig. 6.41), erring onthe side of a more super ior app roach, in orderto reduce the risk of simultaneously exposingthe root of the incisor, which will be in thesame bucco-lingual plane. The aim wouldthen be to move the tooth buccally, hor izon­tally and slight ly superiorly, over the shor t­ened incisor roo t stub and to convert it in to abuccal canine.

Prob lems that may be encountered

If the case is first see n very late and rootresorption of the incisor has destroyed two-

thirds or more, it is usua lly more reasonable10 remove the incisor and to d raw the caninedown into its place <Fig. 6.42). The root of thecan ine will need to be mesially up righ ted andprobably bucca lly torqued . It is then reshapedto disgu ise its original identity and to simu­late the absent incisor.

Complica tions

Does the resorption process stop when thecanine has been moved away from the area(Figs 6.41 d and 6.43)? Controlled studies ofthis unus ual and special situation have notbeen undertaken, but clinical experience indi­cates that it docs. This being so, it must beconsidered worthwhile to plan orthodonticrepositioning of the canine, even though thestakes are high, in terms of risk of losing theinciso r, notwithstanding the treatm ent. In­decision and delay are all too easy to en­counter, and are often encouraged by thepatient, since the condition is usua lly symp­tomless. It is only when the final stages of thedrama are being played out tha i the serious­ness of the consequences become evident tothe pa tient.

Comm unication with the pa tient and theparent, wh en the patient is a minor. is anessential prerequisite in the treatment plan ofeven the simples t orthodontic case. In the dis­cuss ion prior to its commenceme nt, the inher­ent dangers of treatment, however rare,should be presen ted toge ther with its poten­tial benefits. This is particular ly true in thetreatmen t of cases with impacted teeth, andnowhere is it more appa rent than in the casesthat we have described as group 6 canines.The discussion should be illustrated with theuse of the pa tient's study models and radi­ographs, and the risks carefully set off againstthe potential gain for the patien t. This shouldthen be followed up by an ind ividually writ­ten letter summa rizing the points of the dis­cussion - not just a standard pre-trea tmentletter. The letter shou ld be given to thepa tient, and a copy, signed by the patient orthe pa ren t (in the case of a minor), should bekept in the records.

THEORTHODONTiC TREATMENT OF IMPACTED TEETH'42- - - - - - - - - - - - - - - - - - - - - -

(b)

(0) Cd)

Hgure 6.40

(,l-c) From t h~' lateral cephalometric film, the anterior occlu sal film and p anoramic scan, the canines a rc seen to be erupt­ing inlo the place of the resorbing Toots of the a-nt ra l incisors in this 15-yea r-old female. (d) This case W,lS trea ted 24yl'i!rS "go, when bands were used and healing by secondary intention, u~ing p,IC~, was ro utinl'. .'\J" ll' the usc of the sol­dcrcd pal.:llal arch for force application for posterior traction . (e) Th", canines have eru plt.'d into the palate, well clear ofthe apices of the incisors. (f) The (aninI'S arc move"lJbuccally. tg, h) In tra .....ral \'iewl>of the completed result. No bracketswere placed on the ant ..rior teeth-th.. inciso rs we re align ed usin,li; the re'!.li nl·rs. Therefore 1l1"C'b.·...Uy root torque of theleft caninl' wa" no t pcrlomwd. Bo th laterals shed wit hin a ycer post·tn·atml'nl. Some years later, the right ca nine andboth cen tral inciso rs were incorporated into an ext l'nsin' fixl-.J bridge. The Idt ca nine was extracted MilUM" of prob­I..ms with parallelism. (i) an ant ..rior occlusal radiograph of the (tl'mporary!) fixed bridge, 22 yea"" after completion oforthodontic treatm..nt. showin,.; complct...a rres t of the resorpnon pr...c.....••.

PALATALL Y IMPACTED CANINES

(figu re 6.40 CfmlilIJH~/)

Col

Cgl

(il

(h)

THEORTHODONTIC TREATMENT OF IMPACTEDTEETH144----------='----------- - - --

,.J IbJ

,<! 'dJ

Fig ure 6.41

(a,b) rl'riapicaJ \.,ews of the gro up 0 canine with associated severely resorbed centra l inciso r. CC) A variant of the auxil­iary labia l arch to move a tooth huccally. The loop is d rawn upwards and into the sulcus to ensnare the pigtail. (d ) Fourweeks Iarer, the pigta il has elongated. indicati ng progress of the ca nine . (e) After sev eral ad jus tments OVl'T a 3 mon thperiod . the eyelet attachment of the canine becomes visible. (f.K> C linic.l l and pe riapical views of the (in,ll s tage of treat­ment. No te cessa tion of root resorption of the incisor and the gingival condition of th e can ine . (h,i) Idl('1",\1 and anteriorviews I year afte r completion of treatment.

PALATALLY IMPACTED CAN INES

(Figu re 6.41 coulil1ucdl

' e)

(g)

(h)

~1 THE ORTHODO NTIC TREATMENT OF IMPACTED TEETH' 46-----------=-'----'-::..:.......--=----=---=-'-=-'---=----:..--==--=-

Ia

(b l

Figu re 6.42

(a) The initial cond ition. Ib) A peria pical view sho wsadvanced T('S(' rp ti" n nf 11w central incisor rout a...·;f lCiall>d

wi th a canine ad vancing in a line close to the long ilxis oftIH.' incisor. (c) Thc inciso r IV,\s extrilctt'd . an d applia ncesare used to eru pt the can ine in to the central incisor posi ­tion. (Courtesy of Dr T Wein t>cr);t'r.)

'd

PALATALLY IMPACTED CANINES

(b)

(.)

(<)

I,)

'"

wFigu re 6.43

(a-cj Inrra-oral views of a 12-year-old gir l, I year after trauma had severely da maged the maxillary incisors. The teethend ured severa l unsuccessful attempts at root canal therapy, and their extraction was recommended . Id) The periapicalt.'icw shows early oblique apical resorption of the right lateral incisor and the palata lly impacted righl canine, (e-g)Following the extractions orthodo ntic space closu re was per formed and composite build-ups have been placed on thelatera l incisors 10 simulate the extracted central incisors. The remaining maxillary teeth h..we bee n moved mesially 10close spaCC!i. (h) The peria pical view shows no addi tional root resorpt ion 01 the latera l incisor, despite it" subs tantial

positional change. (Figure 6."3 COllfirmedl

THEORTHODONTIC TREATMENT OF IMPACTED TEETH148---------~-+---------

(Figu re 6.43 cmlli um'd )

<01

REFERENCES

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Bass TB (1967) Observa tions on the misplacedupper canine tooth. Dell! Pract Dent Rec18: 25-33.

Beck BW, Harris EF (1 994) Apica l root reso rp­tion in orthodomicall y trea ted su bjects: ana ly­sis of ed gewise and light wire mechanics. Am, Orl llod DI'll fofae Or t/wp 106: 350-61.

Becker, A (1978) The med ian d ias tema. DentGin N Am 22: 685-710.

Becker A (1984) Etiology of maxillary can ineimpactions. Am I Ortl/Od 86: 437-8.

Becker A (1995) Pala ta l canine displacement:guidance theory or an anomaly of genetic ori­gin? AI/Sit' Ort/md 65: 95-8.

Becker A, Zilberma n Y (1975) A combined

<hI

fixed-removable approach to the treatment ofimpacted maxillary canines. / Clin Orthodont9: 162-9.

Becker A. Zilbe rman Y (1978) The pala tallyimpacted can ine: a new approach to its treat­ment. Am / Ort/lOd 74: 422- 9.

Becker A, Smith P. Behar R (l 9H1 ) The inci­dence of an omalous lateral inciso rs in relationto palatally-displaced cuspids . Allgle Ort/wd51: 24- 9.

Becker A, Koh avi 0, Zilbcrman Y ( 983)Periodontal s tatus following the alignmen t ofpalatally impacted canine teeth. Am J Ortlwd84: 332--6.

Becker A, Shpack N, Shtcycr A (1996)Attachment bonding to impac ted teeth at thetime of surgical exposure. Eur / Crthod18: 457-63.

Bjcrklin K, Kurol J, Valentin J (1992) Ectopiceru pti on of maxilla ry first perma nent molarsand associat ion w ith other too th and develop-

PALATALLY IMPACTED CANIN ES

men tal d isturbances. Eur JOrthod 14: 369-75.

Brin I, Becker A, 5halhav M ( 986) Position ofthe maxillary permanen t canine in relation toanomalous or m issing lateral incisors: a popu­lation study. Eur1Orthod 8: 12-16.

Brin I, Becker A, Zilberman Y (1993a)Reso rbed lateral inciso rs ad jacent to impactedcanines have normal cro wn size. Am JOrthod104: 60-6.

Brin I, Solomon Y, Zi lberman Y 0 993b)Trau ma as a possible etiolog ic factor in m axil­la ry cani ne impaction. Am 1 Ort/lOli DentoiacOrt/wp 104: 132-7.

Broadbent BH (1941) Ont ogenic d eve lopmentof occlu sion. Angle Orthod 1: 45.

Cra mer HC (1929) Den tal survey of one thou­sand adu lt males: a statistical stud y correlatedwith physical and labora tory findings. J AmDenl Assoc16: 122.

Cresc in i A, Clauser C, Giorgett i R et al (1994)Tu nnel traction of Intreosseous impactedmaxillary canines: a three-yea r periodontalfollow-up. Am 1 Orthod Dentoiac Orlhop105: 61- 72.

Dachi 5F, Howe ll FV (1%1) A su rvey of 3874routine full-mouth rad iographs. II . A stud y ofimmpacted tee th. Oral Swg Oral Med OralPath 14: 1165-9.

Ericson 5, Kurol J (1987a) Incisor resorp tioncaused by ma xillary cuspids. A rad iographicstudy. Angle Orthod 57: 332-45.

Ericson 5, Kur ol J (1987b) Rad iog ra phic exam­ination of ectop ically eru pting maxillarycanines. Am J Orthod Dentoiac Ort hop91, 483- 92.

Ericson 5, Kurol J (1988a) Resorp tion of max­illary lateral incisors caused by ectopic erup­tion of the can ines. A clinical an dradiograp hic analysis of pred isposing factors.Am 1 Orthod Dentofae Ort/lOp 94: 503-13.

Ericson 5, Kurol J (1988b) cr d iagnosis ofectopica lly erupting maxilla ry ca nines - acase report. Eur 1Orlhod 10: 115-20.

Ericson 5, Kurol J (198&) Early trea tme nt ofpa latally erupting maxillary canines byextraction of the primary canines. Eur J

Orthod 10: 283-95.

Fearne J, Lee RT (1988) Favourabl e sponta ­neous eruption of severely di splaced maxil­lary canines wi th associated follicu lard isturbance. BrJ Orthod 15: 9.3-8.

Free man RS (1994) Adult trea tment withremoval of all fou rs permanent ca nines . Am JOrthod Dentoioc Ort/lOp 106: 549-54.

Friel ES (1949) Migration of teeth. Dt'llt Rt'C69: 74.

Hitchin AD ( 956) The impacted maxillarycan ine. BrDent J100: 1- 12.

Howard RD (1967) The u nerupted incisor.A study of the postoperati ve erup tive his toryof incisors d elayed in the ir eru ption by super­numerary teeth. Dell! Freet Dellt Ref 17:332-41.

Ingber 5} (1974) Forced eruption . Part II . Ame thod of treating non-restorable tee th ­periodontia! and res torati ve considera tions. JPerioiont 45: 199-206.

Jacoby H (1979) The ballista spring system forimpacted tee th . Am JOrthod 75: 143-51.

Jacoby H (]983) The etiology of max illarycanine impactions. Am 1 Orthod S4: 125-32.

Joh nston WO (1969) Treatment of pa latallyimpacted canine teeth. Am JOrthot1 56:589-%.

Kohavi 0 , Becker A, Zilbe rman V (1984a)Su rgical exposu re, orthod ontic movemen tand fina l too th position as fetors in pe riod on­tal brea kdown of treated palata lly impactedcanines. Am JOrttiod185: 72- 7.

Kohavi 0 , Zilberman Y, Becker A (1984b)Period on tal status following the alignm ent ofbuccally ectop ic maxilla ry can ine teet h . Am JOr/hod 85: 78-82.

Kokich VG, Mathews Dr (1993) Su rgical andorthod ontic manageme nt of im pacted teeth.Denl cu« N Am 37: 181- 204.

Korn hauser 5, Abed V, Haran 0 , Becker A(995) The resolu tion of palatally-impactedcanines using palatal-occl usal force from abuccal auxilliary. Am 1 Orthod Dcntojac Orthop110: 528-34.

Lapp in MM (951) Practical management of

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH,so--------_-.::.:=-=-==::...-===-=~::...:.:::.:::

the impacted maxillary ca nine. Am I Orthod37: 769- 78.

Lewis, PO (1971) Pre-orthod on tic surgery inthe treatment of imp acted canines. Am IGrtnod 60: 382-97.

Linda uer 5J, Rubinstein LK, Hang WM et al(1992) Can ine impaction identified early withpanoramic rad iograp hs. J Am Dent Asscc123, 91- 7.

Loberg EL, Engs trom C ( 994) Thyroidad ministration to red uce root resorption.A I/glc Urtuod 64: 395-400.

Mead SV (930) Incide nce of impacted teeth.lnternat I Orthod16: 885-90.

Miller BH (1963) The influence of congenitallymissing teeth on the eruption of the uppercanine. Dent Pract Dent Rec 13: 497- 504.

Mon teliu s GA (1932) Impacted teet h. A com ­parative study of Chi nese and Caucasian den­tit ion s. JDell t Res 12: 931-8.

Mossey PA, Campbell HM, Luffingham JK099..1) The palatal canine and the adjacent lat­eral incisor: a study of a West of Scotlandpopulation . Br J Orthod 21: 169-74.

Oliver RG, Mannion ]E, Robinson JM (1989)Morph ology of the maxillary lateral incisor incases of unilateral impaction of the maxillarycanine. Br / Orthod16: 9- 16.

Or ton ns. Garvey MT, Pearson MH (1995)Extrusion of the ectopic maxillary canineusing a lower removable ap pliance. Am IOrt/lOd 107: 349-59.

Peck L, Peck 5, Attia Y (1993) Maxillarycanine-first premola r transposition, associ­ated dental anomalies and genetic basis.Allg/e Grtuod 63: 99-109 .

Peck 5, Peck L, Kataja M (1994) The palatally

displaced canine as a de nta l anomaly ofgenetic origin. Ang/e Ort/lOd 64: 249-56.

Peck S, Peck L, Kataja M (1995) Palatalcanine displaceme nt: gu idance theory or ananoma ly of genetic origin? Sense and non­sense regarding palatal canines. Angle OrO/OO65: 13-17.

Poumparos E, Loberg E, Engstrom C (1994)Thyroid function and root resorption. AngleOrthod 64: 389-94.

Power SM, Short MBE (1993) An investig atio ninto the response of pa lata lly displacedcanines to the removal of deciduouscanines an d an assessment of factors con­tributing to favourable eruption. Br I Onhod20: 215-23.

Proffit WR (]992) Contemporary Orthodontics.Mosby Year Book, St Louis.

Stern N, Becker A (1980) Forced eruption: bio­logical and clinical considera tions . ] OralRehab 7: 395--402.

Takahama Y, Aiyama Y (1982) Maxillarycanine impaction as a possible microform ofd eft lip and palate. Eur I OrtllOd 4: 275-7.

Thilander B, Jacobson SO (1968) Local factorsin imp action of maxillary canines. Acta OdontScond 26: 145- 68.

Vanarsda ll RL, Corn H (1977) Soft-tissuemanagement of labially positioned un eru ptedteeth. Am I Orthod 72: 53-64 .

von de r Heydt K (1975) The surgical uncover­ing an d or thodontic pos itioning of uneruptedmaxillary canines. Am I Orthod68: 256-76.

Zilberman Y, Cohen B, Becker A (1990)Familia l trends in pa latal canines, anoma louslateral incisors and related phenomena. Eur ]Ontiodonr 12: 135-9.

7 OTHER SINGLE TEETH

CONTENTS • Buccall v impacted canines • Mandi bu lar canines • Mandibu lar secondpremolars • Maxillary second premolars • Maxillary first molars • Mandibu lar secondmolars • Impaction and crown resorptio n • Infraocclusion 01permanent teeth• Dentigerous cysts

Aside from the third molars. the maxillar ycanines and central incisors are the principalteeth that may become impacted , but. fromtime to time, other teeth may also be a ffected .For so me of these tee th, fam iliar pa tternsemerge, typica lly affecting the same tooth andwith the same aetiology in ma ny of the cases.In others, unu sual pa thology is involved ,which may affect any tooth or group of teethand is therefore quite unspecific. Neverthe­less, even with a wide ly heterogeneousgroup, trends may be recognized and treat­men t p rotocols may be suggested to cover agood proportion of them .

BUCCALLY IMPACTED MAXILLARYCANINES

As we have poin ted ou t in Chapter 6, crowd­ing is the principa l cause of buccally d is­p laced cani nes, and the scenario by which itoccurs was described there. In a small num­ber of cases, the canine 's eru p tion is delayedor interru pted , and remains in its very pa lpa­ble and unerupted buccal position indcfi­nitely. In others, it may erupt higher up in the

area of the sulcus oral mucosa, which createsa poor gingiva l attachment. From the peri­odontal po int of view, having only thin oralepithelium cove ring the root leaves thepatient with a delicate and eas ily traumatizedatta chment apparat us. Surgical and or thodon­tic tre atment were described in Cha pte r 3 toresolve the problem.

Occasion ally, one may sec a pa tien t inwhom the unerupted canine is on the buccalside of the alveolus, with its crow n very highan d strongly mesially d isplaced , labial to thelater al and central incisor root apices .Although these art' usually palpable, theunu sua l height of the tooth in the sulcus maylead to the clinical diagnosis being missed .Because of the obliqu e angle at whi ch theX-ray con e is directed , the periapical radio­graphs will produce a mislead ing picture thatsho ws the superimposition {If the ecto pictoo th more inferiorl y depicted on the roo t ofthe lateral incisor, giv ing i t the ap pearance ofits being palata lly d isp laced .

Surgical access is good , bu t the ability top rovide a satisfactory or thod ont ic s trategy 10red uce the impactio n is poo r. This is becausethe high buccal canine tooth must be brough tinferiorly and bu ccally , in a manner that

THE ORTHODONTIC TREATMEN T OF IMPACTED TEETH152__---' ---'::...:--'--:.:.::-=-:::.::.---'--'--=----'--'----'--.::.:.:=-=~

,., lb)

(d (d '

Figu re 7.1

(<1, b) Clinica l views showing an over-re tained deciduous right maxillar y canine. Noll' the labi al and dis tal tipping of thl:'right latera l incb or crown and pa lal,,1 root pos ition. (c) Ante rior occlusal view showing superimposition of c<l ninccrown an d latera l incisor roo t on right side. Clven the palatal root displacement of the lateral incisor, the canine cou ldbe inferior 10 the lateral's mo t on the palatal side or superior to the root on the labial. (d l A sec tion of the panoramicview, to show the se vere ffiL'Sial displacement and ul\usuallwi~ht of the canine . Taken togl'lhcr with the an ter ioroc clusal view, this shows the caninetu be bu ccal. (e, fl Para llax views confir m the buccal d iagnos is. Ig , h) Extraction ofril':ht deciduou s and permanent cani nes only and maxilla ry arch mechanotherapy has achieved l' f'ilCt' C!<"'UT(', and goodinter cu spa tion in class 1 on the left and in class 2 on the righ t. with mid line correct ion.

OTHER SINGLETEETH

(Figure 7.1 ((Jlrt in llt"d)

(1.')

'.'circumvents the roo t of the adjacen t incisor.This would involve its being d raw n in a semi­circular flan king movement, a round the lat­eral incisor root, in an area where the alveolarbone is too nar row to allow one root to passby another. As the canine is moved labially,the labial plate of bone thickens and alsoremodels lab ially. However, it does so to alesser extent than the dental movement, untilthe root of the tooth no longer has a labialpla te a nd is covered only with gingiva l softtissue. The prospec ts for mu co-gingivalsurgery, per formed at the time of exposure,are very limited for the high buccal can ine,

(hl

and so we mus t expect to see a lon g clinicalcrown and a poor prognosis for the tooth inthis position (Kohavi et al, 1984).

As a general rule, the mo re seriously dis­placed buccal canines of this type arc bestextracted and, as far as possible, the decidu ­ous canine left in place, preferably with itscrown prosthetically enlarged . If the decidu­ous canine has a poor prognosis, an earl ydecision regarding space closure should bemade. Where appropriate, con trolled ortho­dontic space closure may then be carried out,with or without a compensating extraction onthe opposite side (Fig. 7.1).

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH154 ~::..:::~======~==='__

MANDIBULAR CANINES

Since they ar c very infrequent, little may befound in the den ial litera tur e abou t theimpaction of mand ibular permanent canines,aside from the od d case report. They seem tooccur mainly in associ ation with an unre­so rbed deciduous pred ecessor; however, theyare sometimes st't' n lon g a fter the d eciduoustooth has shed normally a nd there is a rela­live shortage of space in the immediate area.They may also be foun d to be present as theTI.'SUIt of an obstruction, such as a supernu­merary tooth or odontome. Often located onthe lingu al side of the alveolar process , theywill appear as ,'I palpable hard swelling underthe lingual mucosa, although they mayequally be found buccally ectopic or in thegenera lline of the arch .

The periapical rad iograph will most oftenprovide adequa te qualitative informationregardi ng the ma ndibular cani ne, un less it isvery deeply displaced . This is because it ma ynot be possible to insert the film suffic ientlydeeply into the lingua l sulcus. In these cases,an anteriorly rota ted lateral oblique film ma yprovide a better view of the too th. Since thesetwo views are taken close to the horizo ntalplane, a true occlusal view will be need ed toaccuratel y localize the too th.

Just occasionally, a single mandibular caninemay be grossly di sp laced , mesially an d deepin the basa l area of the mand ible. Its axial or i­entation is hori zon tal, with the crown close toor actu ally crossing the mid line sym physis(Fig. 7.2). In this type of case, extraction willbe the only pra ctical line of treatment avail­able. Given the presence of the roo ts of adja­cent teeth lrnmcdiatcly superior to it and thenarrow dimensions of the mand ible, there isno room for su ccessful orthodontic ma noevre,unlike a similar a nom aly occu rring in themaxilla ry arch.

For mo st impacted mandibular canines,however, a carefu l radiographic evaluation\v iIl indi cate a reaso nable prospect for align­ment (Fig. 7.3). In line w ith the general princi­plcs tha t were sot ou t in Chapter 4, anor thod ontic applia nce is placed and space isprepared in the ar ch 10 accomodate the toothbefore its expos ure is undertaken (Fig. 7.4).

Figure 7.2

The crown of the horizontally impacted right mand ibula rcan ine ove rlies the rooe of the erupte-d ma ndibular canineof the opposi te side. (Courtt.'Sy of Dr T Weinlx-rgc r->

The initial levelling and space-opening arch­wires are rep laced by a heavier base arch ,which will provide the ancho rage for thedes ired traction. A measu red piece of stain­less steel tubing is threaded over the archwireand liga ted between the first p remo lar andlateral incisor to actas a space mainta iner.

A lingually d isp laced canine is usually bestexposed , an attachment bonded to its buccalaspect and the wound fully closed with theresuturcd flap, un less the tooth is very su per~

ficial. In this way , traction from the attach­ment d irect to the labial archwire mayprovide the two directiona l components offorce, i.c. bu ccal and extrusive, that areneeded to bring it to its place. The wire liga­ture pigtail, which was tied to the bondedattachmen t at the time of surgery, is rolleddownwards to furm a loo p, close to the rcsu­tured gingival tissues. A ll clastic chain isp laced across the span bet ween first p remolarand lateral incisor, and its midd le portion isstretched downwards wit h a hac mostat or lig­ature d irec tor and ensnared in the ro lleddown pigta il. This prov ides an eas ily measur­able, light and ver tically d irected force on theimpacted too th, with a wide ra nge of action.

OTHER SINGLE TEETH

C,) lb)

Cd

I,)

Cdl

Figure 7.3

(a) The left mandibula r canine h,lS o.....-n gwssly d is rl ,Kl'l.i di stally andinfer iorl y, because of an od ontomc, an d ts in clos e ,1sSilCiat ion w ith thelow er border of th e ma ndible. (h) A true occlusal view of th eCil n ine/ pr('molar ar ea. (c) After alig nment ,111d space opening, surg icalremoval of ove r-reta ined deciduous tooth and od on tom c has pt'nnilt l'dattachment placement. (d) Rapid im prov ement in positiun h,lSoccu rred. Note the deleterious d flx ts on arch for m and m idline d ue touse of base arch of inadequate size. (e) A pe riapica l \';ew in the latterstages of resolution. (Courtesy of Dr R Rcmano.)

156

(.J

'd

Transposition

A specia l case ma y be made for the buccallyd isplaced mand ibular canine, transposedmesially to the lateral incisor. This is no t anuncommon form of transposition. The crow nof the canine will need to be moved buccal lv,in order to sidestep the la tera l incisor root,before being moved towards the archwirc.As with the parallel situation in relation tothe buccall y displaced maxillary canine,that we hove described abov e, the orthodon­tic and periodontic p rognoses of treatment forthese teeth deteriorates in inverse relation tothe amount an d type of mechanothe rapyus ed .

For thes e tee th. the re rema in three altern a­tive lines of treatment for the non-crowdedC,1St'. The clinician may

THEORTHODONTICTREATMENT OF IMPACTEDTEETH

(b )

Figure 7.4

(a) Expos ure of rig ht man d ibular ca nine with dentiger­ous cyst. Eyelet attachment in place. (b) Fully closed andhealed tissue. xote the use of ve rt ical elasti c in latterstages, to prevent bite opening. (c) Fina l d etai ling of roo tpositi on .

(a) extra ct the canine, leaving the deciduouscanin e in its place, provided its root is ofreasonabl e length and progn osis;

(b) extract the lat era l incisor and align thecanine in its place, leaving the de ciduouscanine in p lace;

(c) de libera tely align the two teeth in a trans­posed rela tions hip, which, in themandibular arch, may offer the op timalsolution (Brezn lak et al, 1993).

In the eve nt of cro wd ing, ex traction o f thedeciduous canine and th e permane nt canine,or of the d eciduous canine and the adjacen tpermanen t incisor, is us ually most approp ri­a te. The space provid ed may then be used forthe relief of crowd ing, as pa rt o f an orthod on­tic treatment programme for other aspects ofthe malocclu sion .

OTHERSINGLE TEETH

MANDIBULAR SECOND PREMOLARS

Crowding and space loss

Perhaps the most common cause of impactionof the second mand ibular premolar is the earlyextraction of its deciduous predecessor,although this has become less frequent with thedecline of caries in the weste rn world. U thisloss occurs in the very young patient, up to theearly mixed dentition stage, there will be con­siderable tipping and drifting of the first molarin a mesial direction. Add itionally, there will bea degree of distal dri fting of the first deciduousmolar of the sam e side, such that the space forthe second premolar may be totally eliminated,before it has the chance to erupt.

The result will be that . this successionaltooth will be blocked from erupting into thedental arch. Its early developmental pos itionbeing slightly lingual to the line of the archand its being prevented from developingsuperiorly in the no rmal manner, it will eithermove more lingually and eru pt on the lingualside, or it may remain impacted and beneaththe 'pitched roof ' formed by the two ad jacenterupted an d tilted teeth.

The radio graphic method for these cases isvery similar to that described for mand ibu larcanine teeth. The periapical film is used toprovide detail, bu t is also a true horizontalview in this area. Therefore it may be su pple­mented by an OCc1US.ll view, to enable accu­rate localization .

Space has to be pro vided for this tooth,whi ch is us ually achieved by the extraction ofthe ad jacent prem olar, wit hin the context ofan overa ll extraction programme aimed atreso lving existing crowding in the entire de n­tition. Alternatively, the drifted teeth must bereslted in their ideal positions, using a fixedorthodo ntic appliance, wit h a coil spring com­pressed between the first molar an d first pre­mola r brackets. This may require that thean chorage be supported by an extra-oralheadgear in the opposing jaw, through theagency of intermaxilla ry (Class Ill ) elastics, toprevent mesial migra tion of an terior tee th.

By whichever method space is made, thetooth will normally erupt with considerablespeed , witho ut fur ther assistance.

A third alternati ve, of course, is to extractthe impacted toot h and align the others intowha tever space rema ins, usually togetherwith extractions made in each of the otherdental quad rants. From the pe riodontal po intof view, excision of unerupted mand ibularsecond prem olars may leave a marked bonydefect in the area, even afte r the adjacenttee th have been fully uprtghted .

Abnormal premolar orientation

The second deciduous mola r of the lower jawhas much to answer for in relat ion to the non­eru ption of its permanent successo r, notmerely when it is prematurely lost owing tothe ravages of caries, but also when there is aprolonged presence. The second premolartooth germ is not always in its ideal develop­mental position , d irectly between the mesialand distal roots of the decid uous molar.Ind eed . an abnormal angula tion or locationseems to be quile freq uent.

The premolar may often be tipped moredistally and initiating resorption of only thedistal roo t, leaving the mes ial roo t of thedeciduous molar largely unrcsorbcd. Thiswill lead to over- reten tion of the deciduoustooth - often despi te the complete d isappear­ance of the d istal roo t and much of the den­tine from within the crown. A periapicalrad iograph will show the prem olar verysuperiorly posit ioned , alm ost inside the distalpart of the crown of the deciduous tooth , bu ta long and thin spicule of the mesial rootremains, gr imly resistin g exfoliation. A peral­Iel scenar io may occur with a resorption ofthe mesial root due tomesial tilt of the secondpremolar from early on in its development,although it seems to enjoy a lower frequency.In either of these cases. for as long as thedegree of tilting is rela tively slight and thetooth is relatively high up in the alveolus,the extrac tion of the deciduous tooth will usu­ally suffice to achieve the rapid and trou ble­free eruption of the premolar too th. Space isnev er a problem in these cases, since the sec­ond premolar has a sma ller mesio-d istalcrown width than its healthy predec essor.

157

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH158- - ------ --- ---'-- - - ---'----'--

A premolar too th that has a st ronger distaltilt is usually situated more apically. and thed istal-occl usal aspect of its crown is in closerelation with the mes ial aspect of the mesialroot of the first permanent molar <Fig. 7.5).The second deciduous mo lar is over-retainedat the time of detection and more thanadeq uately holding the space in the arc h.

In these cases, a space-hold ing device shouldbe used when the deciduous molar is removed,to prevent molar tipping. and an attemptshould be made to uprigh t the premolar. Adevice may be designed in many ways, but

classically a buccal and lingu al bar may be sol­dered to two bands to form a simplified fixedbrid ge, which is then cemented to these teeth.A sing le rig id bar, with a mesh pad at eachextre mity, may be bonded to the buccal surfa ceof first molar and first premolar. and is a fairlygood alterna tive, provided that it is well clearof the occlus ion, althou gh, even in th is situa­tion, it may still be disp laced by occlusa l forcestransferred by bu lky and hard food s.

At surgery, the impacted premolar tooth isexposed in its mesial and occlusal aspectsonly, and , where possible, an eyelet should be

",

Figure 7.S

(.1) A late developing left second premolar, horizontallyoriented. (b) A year lat er, the tooth has moved distally toOVt·rl.lp the mesia l root of the first pe rm.l 0t'n t molar. (c)

Extra rtion reveals some resorption of the mesial roo t ofthe molar. (Cou rtesy of Profes so r Y Zilbt.-ml<ln.)

,<I

OTHERSINGLE TEETH

handed to this area of the crown of the tooth.Since the toot h is fairly dee p down , the flap iscompletely sutured hack in to its place, andthe stainless steel liga ture wire pigtail, tied tothe bonded eyelet, becomes the means ofapplying force to the unerupted tooth. This isapplied from an elas tic module stretchedbetween a hook on the fixed hand of each ofthe two erupted teeth, parallel to and overly­ing the rigid bar. The greater the degree ofmovem ent req uired, the more substantia lmust be the a nchor base, and, in theseinstances, a fixed ling ual arch to the oppos itemolar is preferable.

This area does not provide easy access topermit acid-e tch bonding <Fig. 7.6), and, onoccasion , eyele t attachment will no t be possi ­ble. When this is the case, compromises mayhave to be made in order to sa lvage the tooth.Wider exposure is indicated (Fig. 7.7), and abuccal or lingual extension to the exposuremay be needed . The crown of the prem olarshould be packed with gau ze impregnatedwith Whitehead 's varnish, particular ly in thedistal a rea, where the pack will need to bewed ged be" ....ccn the prem olar crown andmolar roo t. The pack sho uld be sutured. inand left for two or three weeks to preventhealing over of the gingival tissues. Thedelibera te wed ging of gauze into the distalarea helps to d ivert the erup tion pa th of thepremolar in a more mesial di rection, and sub­sequent eruption usually occurs. As waspointed. out in Cha pter 3, howeve r, these pro­cedures will make the establishme nt of anideal period onti um unlikely, an d it isexpected that the clinical crown of the toothwill, in the final erup ted pos ition, be longerand the prognosis poorer them norm al.

While there arc many impacted second pre­molars that may be treated in this WilY, suc ­cess cannot be expected in some of the mo reextreme cases, and the too th has to beextracted (see Fig. 7.5).

Infraoccluded second dec iduous molars

These are a relatively common occurrence,and are know n to shed quite normally in

(,)

(bJ

(d

Figure 7.6

Seria l pe riapica l vi.,w s nf ,1 f,l il•-d attem pt to bon d anEdgewise br acket to an inadequately develo ped sec ondmandibula r premola r. (Cour tesy of Dr D U,lr.Hy .l

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH160--------- - - - - - - - ------

Ibl

'd 'd)

Figure 7.7

(.ll Panoramic view of a case complicated by maxillary im pacted canines, I'lll.~dc\'cl"ping man dibul,tr M'Cund pr",mOlil f5MId total ~ p,lce loss on till' It'ft skit'. (b) A periapical view shows bonding uf an attachment tu the right second pr emola rW,I, achieved only aftt'T wid e t' XpOSUTl' , (c) A similar follow-up r,ldiugr,lph show s improvemen t in till' position of thetooth, but rr estal bone height is deficient. (J ) A pa noramic view Llf the final slages of treatment clearly shows thereduced periodontal prognosis of th e r igh t mandibu lar second premolar. (Courtesy of Dr L Rothst ein.)

most cast's, with only a relatively minor delayin the ir ex folia tion time (Kurol, 1984; Kurolan d Thiland er, 1984). Neve r theless, when theinfraocclu sion is very marked , an extre meverti cal d isplacem en t of the apically p lacedsuccessor w ill be present . Indeed, the apex ofthe roo t of this developing tooth may even

cause a pa lpable prominence in the otherwisesmooth profile of the lower border of themand ible (Becker and Sh ocha t, 1982). In thesecases, it is qu ite imp ractical to attemp t tobond an attachment to th ese grossly di s­placed premolar too th.

Fortunately, with infraocduded tee th,

OTHER SINGLE TEETH

actual spa ce loss within the mandi bu lar de n­tal arch is very minima l Wecker and Karnei­R'em, 1992a,b; Becker et al, 1992) and thisrarel y provides a problem within the ortho­dontic strategy. However, once the infraoo­eluded too th has been rem oved , space lossmay be q uite rapid, a nd a space maintainershould be placed . No attem pt should be madein the firs t ins tance to uncover the verydeeply placed premolar, but , following theremoval of the decid uous too th, the pa tien tshould be followed up over a long period oftime, with an occasional pe riapical radi ­og raph ta ken to check for eruption progress(Fig. 7.8).

Few clinicians have recorded the ir experi­ence with these ext reme cases in the litera­ture, and opinions are strongly influenced bysingle case treatmen ts. However, there wouldappear to be some merit to a 'walt-and-see'policy and some reason for optimism in thesevery special circumstances. lnfraoccludeddeciduou s teeth are associated with a lack ofalveolar bo ne height in the immed iate area.The height from the inferior border of themandible to the occlusal table is significantlyreduced when compa red with a nor mal unaf­fected opposite side (Becker and Karnei R'em,1992b).

Extrac tion of the infracccluded too th ini­tially leads to healing and bone reorganiza­tion, which, in the absence of permanentteeth , will not increase the vertical heigh t ofthe body of the mand ible in that area. If a per­manent tooth is present and then begins toerupt, alveola r bon e developmen t occursbefore an d im med iately following the erup­tion, and the ver tical bony deficiency is eve n­tually mad e good . However. this may bepa rtial only, and a lateral open bite maysometimes persist (Fig. 7.9).

MAXILLARY SECOND PREMOLARS

The most common reason w hy these teethbecome impacted , as with the mand ibularsecond premolar, is related to space loss inthe den tal ar ch, follo wing the early extr action

of the deciduous secon d molar and the drift­ing of the two adjacent tee th, particularly thefirst perman en t molar. It is also tru e thatmesial movement of the first permanentmolar in the maxill a is more rapid than in thema ndible, it more completely closes off thespace, and it does so even in the late mixeddentition stage. Therefore , when space hasbeen lost, the maxilla ry second premolar ismos t o ften to be see n develop ing with its roo tin the line of the arch, and with its crowndeflected palatally and pa lpable on thepalatal side of the alveolar process.

Infraocclusion so metimes affec ts the maxil­lary deciduous second molar too, and , whenthi s is in its severest fonn (Fig . 7.10), the suc­cessional seco nd premola r seems frequen tlyto be d isp laced both palatally and moremesially than usual. It is ofte n ro tated andlocated high in the maxilla, beyond the area,...here it may be expected to be palpable.

Because of the oblique angle of the X-raytube in periapical radiography of this area,the palatally tipped and unerupted secondpremolar w ill be viewed almost throug h thelong axis, and will be depicted on the film asan ellipse. Thi s being the case, it is probabletha t fu rthe r Xcray films are unnecessa ry,par ticu larly if the too th is palpab le in . thepalata l area. Wh ile the con vent iona l (oblique)occlusa l film or a second , laterall y shi fted ,periapical film will offer the opportunity toad d three-d imensional infor mati on, the truevertex view would be more dec isive.

In general, and quit e regard less of theaetiology, second premolars in the max illaryarch will erupt spontaneo usly, and, as thishap pen s, they also spontaneously resolvetheir palatal d isplacement. The only essent ialrequirement is that there be ad equate space inthe arch and that this space be maintained(Fig. 7.lOb). Most often, the second premolardoes not need to have an attachmen t on it,nor is it usually necessary to even expose it.Unlike othe r teeth, the re a ppears to be littl ebenefit in going through the elabora te or tho­dontic and surgical prepara tions that we hav edescri bed in relation to incisor and caninetee th . Little harm will be inflicted by theexposure and bonding of a n attachment, butthe exercise will almost a lways be shown to

162 THEORTHODONTICTAEATMENTOF IMPACTED TEETH

(bl

(d

Ie)

f igu re 7.8

A ",eTit'S of peri apical views of an imp..KI..'\1 ",,,·a 'n<.l pre­mo lar, displaced inferiorly by an inlraocclu d..-d d ecidu­ous second mo lar. (a) the initial vi..,w; (h) after SP.l("(,

reopening: (c) after extr action and Sp.1U' maintainerplac..-men f Id ) spo ntaneous imprt'\'em"'nl; (e) theeru pted tee thNo other Orlhochmlic prtlO.-dun... Worn.' ini­tiated. (Court..""y of Professor Y Zilberman.)

OTHERSINGLE TEETH

(01)

(d

(,)

(b )

Figure 7.9

(a,b) Intra.....ral views of a case in which the left mandibu­la r first dnd second deciduous molars h'ld been infraoc..eluded an d were extracted 18 months earlier. EruptionW ilS initia lly r,l pid, but inmm plele a nd furthe r crupnonhas not occurred. (c) Pa noramic view of ca....•. (Court ....yof Dr M Barvcl.)

(b)

163

Figure 7.10

(a) Characteristic extreme tipping ...f the teeth .1dj.:lCt'nt to an infraoccludcd maxillary deciduous seco nd molar. The St.'C.

ond premola r is displaced su periorly an d mt'Si.llly, exh ibiting d ma rked distal ...ricnta tion. Ib) Spare r~l!>,l i ning andmain tena nce , with extracti on of the infraooduded deciduous mola r. h..1S res ulted in sp...n taeeous conccnon of toothposinon. Eruption is im minent.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH164 -.::.:::..:=:.::==-.::.=======-=::.:

(.,(bl

(01 (d '

Figure 7.11

(a) Incomplete eru ptio n of the maxillary first per manen tmolar. due to abnormal angulation of its long axis. It hasbecome impacted bClll"llh the di stal bulbosily of thed eciduous second molar. (b) The removable appliancecarries flvc retention clasp s and a palatal 'fing er' springthat traverses th.. occlusal surface ()f the partially eruptedfirs t molar. An ac rylic bllll nn is placed on thai portion ofthe spring that cernes into contact with the occlusal SUT­

face of the first mola r. (c) The incompletely sea ted appli­ance shows the spring in its passive mode, d ista l to themolar. (d) The patie nt has brought the spri ng mesially,prior to fu lly sealing the applia nce. (e) The molar is dis­impacted and in fu ll (Class II) occlusion . (I, g) Lateraloblique extra-oral films before and after treatment showthe ad vanced resorpti on of the second decid uous molar.

(e

OTHER SINGLE TEETH

(Figur e 7.11 cOlrlimlrdJ

have been superfluous, except in the mostexcep tional disp lacements.

MAXILLARY FIRST MOLARS

In the early mixed dentition, one may occa­sionally see the erupting ma xillary molarsbecome caught by the d istal bulbosity of thead jacent deciduous second molar (Fig. 7.11).This is usually an early sign of crowding ofthe dentition, although it may simply be dueto an abno rmal mesial tilt of the first molar.Clinically, the essential d iagnostic criterion isthat the marginal ridg es of the two adjacentteeth arc at different levels, with tha t of thedecid uous tooth being more ocd usallyplaced . In the more severe cases, the mesialmarginal ridge of the permanent mola r isunseen, beneath the area of the distal e Ej ofthe deciduous too th. At best, the dista l cuspsmay be in occlusion with the mand ibularmola rs, bu t usu ally the impaction preventsadequa te eruption for this to occur.Occasionally, the perma nent mola r is corn­pletely prevented from eru pting, and doesno t break through the mu cosa.

165

(g )

A periapical or pa noramic radiograph ofthe area will usually show most or all of thedistal roo t of the deciduous second molar tohave been resorbed and the general long axisand pa th of eruption of the permanent toothto be tipped too far mesially (Fig. 7.11).

To leave a partially erupted molar toothwithout treatment is to invite caries in thelarge stagnation area that has been createdbetween it and the dec iduous mola r, whichserves to compound the existing po ten tialgingival/pulpal prob lem in the area of con­tact. In general, the mesial root of the decidu­ous second molar remains in tact, to retain thistoo th in its place.

If the deciduous second molar is shed pre­maturely or extracted , the permanent molarw ill move rapidly forwards, significantly clos­ing off the space vacated by the lost tooth.within a few sho rt months. The tooth alsoerupts occlusally at the sam e time, and itsmoveme nt has a significant forward transla­lion component, in addition to its mesial tip­ping component. This being so, orthodontictreatment, whose aim is to tip the tooth back toits ideal position after full eruption, wiII gener­ate an excessive distal tip to the molar . whichwill leave the roots too far mesially. Secondly,

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH166- ------ - - ------ - ---- - -the achieved space will require to be main­tained for around 5 years, until all the succcs­sional teeth have erupted. Regardless of howwell designed and constructed the proposedspacc-matntatrung device may be. its place­ment in a 7- Of 8-year-old patien t must provid esome concern vi s-a-vis its deleterious effect onthe lon g-term prognosis of the first molar.

Man y original ideas a nd gadgets have beensuggested to d isim pac t the ectopic firs t mola rfrom beneath the distal bulbosity of thed eciduous second molar, the simp lest ofwhich has been to use an elastic separatingring or othe r form of orthodontic separator,which are normally USl..U to create spacesprior 10 banding molars. These may be suc­cessful in some of the very mild cases,although what frequently happens is that aspace between the tee th is prod uced within aweek or so a fter placemen t of the ring. Theclas tic ring is then rem oved to allow the per­ma nent tooth to eru pt occlusally. In manycases, the molar tips r ight back in to its p revi­ously imp acted position, an d no thing willhave been ach ieved.

This type of relapse may occu r \v-ith anymethod that is only concerned w ith tip pingthe tooth d istally, without p rovid ing for ,1

retention pe riod. The ret en tion period isin tended to permit ad ditional eruption of th etooth, while preventing rclmpactton .

A fixed device has se ver al apparent inher­ent ad vantages , bu t it mu st be rememberedthat the patient is a young child, who may berelati vely unwilling to cooperate in its con ­struction. Additionally, most orthodontis ts donot hav e a selec tion of preformed deciduou ssecon d molar bands, and the placem ent of aband on the permanent molar is im possible inall bu t th e simplest of cases. Suitable condi­tions for com po site bon ding arc also excep­tion ally d ifficu lt to attain in th e mo lar area ofsuch a young child, and results a re u nr eliable.

Nevertheless, appliances have been design­N based on a fixed band on the deciduoussecond molar only, or o n an add itional fixedba nd on the second d ecid uou s molar of theopposite s ide, through the ag en cy of a sol ­d ered palatal arch. A sold ered sp ring isformed on a model. wh ich fits in to the mo stconven ien t and deepest occlusa l pit o f the

ectopic molar and is activa ted prior to cemen­ta tion of th e appliance (Proffit, 1992). It isquite difficult to read just this spring in themou th, which mi'ly make this a one-time-acti­vati on app liance, unless the whole cementa­tion process is repeated .

At first gla nce , a removable applianceseems inappro p ria te, since there aplX'ars tobe no ''''ay o f passing a cantilever springacross the in terproximal area , mesial to thetoo th, to apply the necesS<lry distal force.However. the removable appliance offersexcellent ways of overcoming the d rawbacksd escribed above {Becker, 1977). Good reten­tion is necessa ry, and this is bes t supp lied byp lacing an Adams' clasp on the second decid­uous molar of that side, on the erupted firstpe rmanent molar on the opposite side a nd onthe two central incisors . Additionally. a three­quarter circu mferen tial clasp placed on thefirst de ciduous molar usually offers excellentre ten tive supp or t (Fig. 7.11).

In more severe cases of this type, theresorp tio n process will have completely elim­inated the dis tal root of th e deciduous molar,and, if careless probing is performed with asharp explorer, pe rforation at the d istal aspectof the decid uous mo lar is very likely to occur.Clini cally, the sharp enamel edge at the cervi­cal margin of the crown and the abruptabsence of continuity may be quite obvious,in the same way as is seen with any decid u­ous too th immediately p rior to its normalshedding. In this area, former pulpal tissuewill have merged with the surrou nding gingi­val tissue. Inflam mation of this tissue at thisju ncture will therefore no longer give rise to apulpitis, and it will repair sy m ptomlcssly, aswi th an y other inju red gingival tissue.

In th e cases of this type with which wehav e had experience, there have bee n noad verse clinical sy mp toms related to thedecid uous second molar tooth, nor has peri­ap ical rad iolu cency been evident on X-ray tosuggest pu lp death. Extraction has not beenreq uired, and the too th has remained to act asa natural space maintainer until shedding hasoccurred at a m uch later stage, closer to thenormal shed d ing tim e and la te enough to findthe second premola r eru p ting rapid ly there­a fter. This is p referable, fro m every point of

OTHER SINGLE TEETH

view . to ext raction and replacement by anart ificia l sp ace main tainer.

To find the parallel s itua tion in themand ibular arch is very rare. How ever. man­agement wou ld be very similar to w hat hasbeen described for the maxillary first molar.

MANDIBULAR SECOND MOLARS

Impaction of the mand ibu lar second mo lar isuncommon, but, when it occu rs, it is verysim ilar in its appearance to that so ffl...-quentlyassociated wi th third mo lars. Almost inva ri­ably, the Impaction is due to a mesial inclina­tion o f the tooth, which bri ngs it in to con tactwith the d istill side of the firs t molar , belowits bulbosi cy an d d ose to the cervical area.This, too, is p roba bly a sig n of a sho rt archleng th an d retromolar cro wd ing.

Unlike the maxillary first molar , the mesi­ally impac ted mand ibu lar second molar isfrequ en tly unerupted. and us ua lly comes tolig ht in a rou tine dental examination, when itshows up on the bite-wing rad iographs.How ever, this view cannot replace the peri­apical film, a lateral oblique extra -oral view ora panoramic scan, which will show d etails ofthe tooth, from crow n to apex, a nd its rela­tions hip w ith the unerupted third mola r. Thetoo th ma y also have a bu ccal or ling ua l tilt,wh ich will ge ne rally be revealed by palpa­tion, alt hough an occl usal view will serve toco nfirm.

Local treatment

If treatment is to be pe rfo rm ed on ,1 localbas is only. in the absence of any other form ofconcurrent malocclus ion, then the firs t partof the trea tment involves the surgica l removalo f the overlying mUCOS<l, to expose theocclusal su rface. As with the maxilla ry firstmolar that we have d iscussed abo ve, aremovable appliance may be used . ..... ith thesame mechanical principles (Becke r, 1977) .

Alternative fixed-appliance method s abound,but their d esign is too frequent ly restricted to

jus t two or three teeth. which may serious lyundermine the an chorage. Id eally, teeth o nbo th sides of the mandibular den tal archshould be included in the anchorage unittMajoura u and Norton, ]995), in order to pre­vent u nwanted movement of other tl,t..th inthe a rch , pa rt icularly to eliminate the possibleoccu rrence of lower incisor crowding . A min i­mum suggested anchorage unit shou ldinclud e fixed band s on bo th first molars,joined by a sold ered lingual a rch, and ortho­dontic bracke ts on the p remola rs of thea ffected sid e.

The active element may be constructe..d inone of fou r way s:

(a) A free-slid ing sectional w ire is s lottedinto the brackets and the molar tu be onthe affected side, activated by an elasticmodu le, with its d istal end latching o n toa sma ll a ttachment on the buccal orocclusal sid e of the impacted tooth .

(b) A similar method is used , em ploying ,1

compressed coil spring (Fig. 7.12).(c) A la rge and stiff open loop o f rec tangu lar

wire is placed in the d istal end o f a bu ccaltube or wide Siamese bracket on themo lar and designed to widely encircle theimpacted tooth. with a small helix at itsex tremity. By tying a stain less steel liga­ture be tween a bo nded evclet o r buttonon the OCd US.1l of this too th an d the smallterm inal loo p, d istal p ressure is broughtto bea r on the impacted mo lar (Majourauand Norton , 19(5).

(d) A co mplete ro und wire loo p with a d is talhelix may be slott ed into buccal and lin­gual horizontal tu bes on the mo lar band.Activation is made as for (c) by tying as teel ligature be tween th e helix an d anattachment on the tooth (Fig. 7.13).

Treatment as part of a comprehensiveorthodontic treatment p lan

For most cases, some form of overal l ma loc­clu sion is presen t, for which treatment needsto be prescribed . The resolution of theimpacted tooth shou ld be in tegra ted in to thegeneral trea tmen t plan .

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH'68- - - - - - - --- ------- - - - - -

i,' ib'

ie) (dl

Figu re 7.12

(a,b ) A roil ~pring ts threilJt...J on to ... sectional arc hwjTt', which is slottt.'d inlo the distalend of a buccal tube on the firstmol ar band. The d b l,11 end of the win.' carries a welded stop or cross-piece, wh ich permits com pression or the roilspring .1g,li nst ,I hutto" or eyele t attachment on the second molar. A lingual arch ,In ,l fully bracketed appliance is pre­sent fur additional anchorage. (c.d) Panoramic views before and ... Iter trealmen\.

OTHER SINGLETEETH

If th e overall malocclusion requ ires extrac­tion, consideration should be given to theex traction of this im pacted too th, toget herwith appropria te ba lancing an d co mpcnsat­ing extrac tions in the othe r quad rants of th emouth (Wilson, 1966; Staggers, 1990; Richard­son an d Richardson , 1993). This is not a fre­quent extraction of choice, but, under thecircu mstances of a very d ifficu lt impaction, itshould be considered . This ena bles thed ispersa l of m ild cro wd ing to be effectedwith grea t facility, w ithout the need for theextens ive root u prighting mo vem en ts tha tarc seen with p remolar extract ions. HO\\'­ever, the o rthodontist will be countin g onthe favou rab le eruption of the third molars(w hic h w iII be sign ifican tly ea rlie r in thesecases) and thei r spontaneous alignment.Shou ld th is not occur, a fu rth er period oftreatment will need to be init ia ted in th eyoung adult stag e, ai med at u prigh ting themesial ly li pped th ird mo lars, from a positiontha t may be reminiscen t o f the initial posi­tion of the ex trac ted second molar! In thiss itua tion, the above proced ures ma y beap p lied to bring about third -mola r upright­ing, in exactly the sa me way as with seco ndmo la rs .

Perhaps th e best way to visualize thepo tential influence of the extra ction of d iffer­ent groups of teeth , is on the panoramic rad i­og rap h. With a mesially tip ped second molarin an ex tracti on case, the loss of a first or sec­ond prem olar end the mes ial move ment o fthe first mo lar may often free the too th toerupt, but th e tipping will remain, an d mayeven become worse, with the toot h ap pea ringto 'fall (J ilt on its face' . Uprighting will th enneed to be u nd ertaken , using the existingmulti bracketed appliances .

Where the mandibular arch is well alig nedor sligh tly cro wd ed, me sial to the fir stmola rs, bu t there is a Cla ss 11 rela tion sh ip orcrowd ing of the maxillary den tit ion, all theupper an d the pos terior lo wer teeth willproba bly need d is tal mo vement, ra ther tha next rac tion. This w ill genera lly be pe rformedwith the use o f an ext ra-oral hea dgea r, tomove the maxillary tee th d istall y and thus toprovide the space necessa ry for the align­ment of the max illary teeth. If Class III

in termaxillary elastics, su pported by thehead gear, arc used aga inst a lo wer appli­ance, whose purpose is to mo ve themandibular mo lars distall y, the force will betra nsfer red through inter proximal contactsto the second molars, which wiII initiallyresist the movement. However, if the seco ndmolar is tilted less tha n 45° and is in con tactwith the d ista l of the first molar crown,above the eEl a rea, the tooth will ultimatelvt ip d ist all y a nd uprigh t, while the first mola rwill itself be tipped dis ta lly. Once the secondmolars have erupted, the d ts talizing force isd iscon tinued , an d the first molar w ill the nspontaneously tip forward until residu alspace has been closed off.

IMPACTION AND CROWN RESORPTION

In teet h that a rc u nerupted over many yea rs,the ou ter ena mel epitheliu m may occasion­ally brea k down, and d irect co ntact betweenbone and ena mel occu rs. In time, th is mavlead to resorption o f the enamel, often wit hthe laying d own of bone in the resorptionlacunae. Any tooth may be affec ted,although it te nds to occu r in adu lts whosed en titi on is established and w he re theuneru pted too th m ay ha ve been replacedp rosthetically. Rarely, it may occ ur in ayou ng pe rson, for whom there is a relat ivelygreater im po rta nce in b ringing the tooth in tothe d en tal arch. The firs t clue to its ex istenceis seen rad iog ra phicall y, w ith d ifficulty ind is ting uishing the outline of the dental folli­cle on a radiograph . Thi s usua lly s ignifiesthe init ia tion of a replacement resorp tionp rocess of the en amel, w ith bone bein g la idd own in tho area. In its more ndvnnccdstages, th e radiogra phic appearance of thetooth shows a loss of the sha rp outline of thecrown and , la ter s till, a reduction in theradiopacity of the crown (Fig . 6.11), associ­ated w ith a s tea dy decalcifica tion of theena mel (Blackwood , 1958; Azaz an d Shtcycr.1978).

In order to move this too th or thodonti­ca llv, the entire crown area must be dis­sec ted free of the bone and a pack inserted top revent the heali ng bone fro m again coming

THEORTHODONTIC TREATMENTOF IMPACTED TEETH170---------- --- - --------

(,)

(el

in to con tact w ith the ena mel surface . A p re­formed crown would be n better altern ativ e,bu t access to the tooth is too co mp ro mised toallow its proper adap tation and cementation.At the same tim e, orthod ont ic force sh ouldbe applied 10 the too th and its activity main­tai ucd by frequen t re-Iige tlon .

INFRAOCCLUSION OF PERMANENTTEETH

Ea rlier in thi s cha p ter, we discussed infr aoc­eluded deciduous tee th. In the permanent

(b )

Figu re 7.13

(,1) Button attachments pon ded buccally and lingually toImpacted second molar. (b) A wire !lX1P carrying a J ist ,!!lwlix is slott<XI into buccal and lingual tubes un till' m"I.Hband . The wi re loo p is compressed by tying :-lct'l liga­tun'S between the butt on s and dista l helix. (c) The fina lresult.

d entition (Fig. 7.14), the same clinica l p ictureis usua lly referred to as 'primary failure oferuption' (Pro ffit and vig. 19H1) Of as 'se c­ondary ret ention' (Raghocbar ct al. 1992),and, in this cond ition, the teeth are sometimescompletely co vered and not visible intra­ora lly. This co nd ition is due to an kylosis(Raghoeba r et .11, 1992). a nd the infrnoccludcdteeth do not respond to orthod on tic force. It isge ne rall y believed that the teeth had origin­ally eru p ted and subsequent ly become an ky­losed. an d the ir ve rtical developmen t hadstopped at that po int. Some o f the moresevere cases may exhibit Intraoccludcd teeththat are situat ed so vertically d istan t fro m the

OTHER SINGLETEETH

I"

Ib'

Ie)

Figure 7.14

(al A normal occlusion of th c posterior teeth is present onthc right sidc. (bl A SC\'L'Te lateral upt'n bite has devel­oped on till' left sidc, due to primary failure of erupt ion.(e) Thc panoramic radiograph shows n 'lJ' ma rkedinfr"..cclusion of tIll' left mandibular first molar " nd, to alesser L' xtL'n t, .11"., nf the [,'fl maxilla ry ",,-'Cun d premolarand firs t molar.

occlusal p lane that it is hard to imagine themever having rea ched the oral cavity. particu­lar ly in the pe rmanent d en tition . With contin­ued ver tical g rowth of the ad jacent teeth andalveolar bo ne, the ankyloscd tee th becomerelatively lower and lower in the ..alveolus,until they become hidden by the g ing ival tis­sue and, sometimes , even by bo ne . Given thatthese tee th cann ot be orthod onticall y moved ,their 'absolu te' a nchorage po tential may beexp loited to o rthodontically al ter the positionof ne ighbou ring teeth (Fig. 7.15).

Pro ffit and Vig (1981) list the characteristicsof p rimary failu re of eru p tion as follows:

(a) posterior tee th on ly, exclud ing incisors;(b) some erupt and then undergo submer­

gence as in infrnoc clud cd teeth, others areuneru pted teeth w ith a la rge follicle;

(c d eciduous and permanent teeth involved;(d ) usually unilatera l and asymmetric;(e) tend ency for ankylosis, although not ini ­

tia lly an d no respo nSt' to o rthodonticforces;

(0 or thodontic treatment leads to ankylosis;(g) no family history.

Their conclusion is tha t orthod ontic treat men tfor these patients is not advised.

Contrary to the view o f Proffit and Vig(981), however, there mav be a fam ilialp red ilection (Raghoebar ct ~l, 1992). Figur e7.16 shows panoram ic rad iograp hs of threechild ren in one family, together wit h tha t ofth e father and the pa terna l gra nd mother, toshow the d iffer ing exp ress ion of the ph cn om­enon for each of these affected F't'rsons.

Orthod ont ic extrusive forces will hav e noeffect on the infrnoccludcd teet h, an d willtend to intrud e the adja cen t teeth towards thelevel of the infra occluded teeth . By seiz ing theinfraocclud ed teeth with extraction forcepsand ap ply ing minimal pressure, just sufficien tto obtain a very mino r degree of mob ility ofthe tee th, one may effectively break the anky­lot ic ju nction. Howeve r, healing is rapid, andthe enkvlosis will soo n become re-cstab­lish ed . For this reason. orthodontic correctionis not usua lly attem pted .

Nevertheless, if a single central incisortooth is a ffected in a you ng pa tient, the

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH172_______ ______::..::.....-.--.::..::..c ~~"__________'=__=~

(b)

Fjgure 7.15

(a) An in fraoccluded It'l l maxillary inci~lr. (b) A periapi­cal radiog raph of the tooth to !Ohow absence of laminad ura over much of the root surface. eel Exp loiting simplelevelling and align ing archwires has also eliminated thedeepened overbite, by dr,lwin~ the other tl>cth to the.1nkyluSI..,j tuo th, (Cou rtesy of I' ru fl'Sst ,r Y Zilberrnan.)

(el

or thod on tist lll,'y not be p repared to acceptthe 'no trea tment' verdict. 1£ the paren tsund erstand the poor progn os is, treatmentmay be att empted , provided that attendancefor freq ue nt activa tion is assured . Beyond thetreatment of these isolated and accessibleteet h, attempts to resolved the impac tion ofmost other tccthwbose roots have undergoneankylosis o r external res or p tion are usuallyvery d isa ppointing .

Aside from naturally occu rring ankylosis,there mi' Ybe reason 10 suspec t the possibilityof an iatrogenic variety . In the past, it was

common to find an oral su rgeon widelyexposin g th e crown of the im pacted tooth,dow n to the ccrn cn to-cnamcl junction andbey ond , with consequent ins trumen tation ofthe root surface of th e tooth . It mi'ly be thatsome of the blame for the relative ly infre­quent anky losis of exposed impacted teeth isd ue to this type of unnecessa rily aggressivesurgical p roced ure.

External root resorp tion that has led to amerging o f the period ontal a nd pupal tiss uesis a rare condition tha t may cause a non­ankyloti c infraocclusion. Treatmen t requ ires

OTHER SINGLE TEETH

(d

te

(b'

(dl

Figure 7.16

A fanuly includ ing (a) grandmother (b ) father and (c-c)thre-e• siblings show ing varying expression of primaryfailu re of eru pt ion.

174

surgical exposure of the resorp tion defect, itsdebridement and elimination with an amal­gam filling. At the same time, roo t canaltherapy mu st be initi aled . After healing, thetoo th may he ali gned using convention alor thodon tic methods (Fig. 7.17).

DENTIGEROUS CYST

Cysts of any sou rce that a rise in close p rox im­ity to teeth will displace those teeth ah ead ofthe expanding cyst (Sha fer et .11. 1983).Professional intervention may influence thefuture o f the d isp laced tooth, dependingupon the type of treatment employed toresolve the cyst. The cyst may be ope ned. andits lin ing completely shelled ou t, in a proce­dure called enuclea tion, with the surgical flapreplaced 10 completely close off the exposedbone. The cavity th at wa s formerly occupiedby the Cys t is now scaled off from the ex terioronce ag'ain. It will fill with blood clot. andhealing is by primary intention. The un­erupted too th becomes deeply buried in thenewly form ing ho ne, and it will need to eruptthro ugh this repairing tissu e. The p rog nosisfor its eruption would appear to be in inversep roportion to its di stance from the su rface.Nevertheless. th is app roach is pa rticularlysu itab le if the cyst is due to chro nic pe riapica lin flam mati o n of the dec id uou s too th, inw hich case it is termed a radicul ar cyst.

A de ntigerous cyst arises from the ou teren amel epit heliu m of the develop ing too th,after crown development has been com­p leted , and the cro wn of the tooth is locatedwi thin the cyst. Th e line of tre atment tha t isus ually offe red is referred to as marsupializa­tion. Th is involves opening the cys t into theora l cavity at its most su pe rficial poin t, andmaintain ing the pa tency of this ori fice over alon g period of time. Th e cut lin ings of the cystand the oral mucosa fuse to become con tinu­ous with one a nother. In time, tilt' lined cavitybecomes smaller and sma ller, as bony regen­eration occur s, to fill in fro m the bottom up.As it d ocs so, the too th gcncraly progresses,in the va ngua rd of the reg enera tion .

Sponta neous resolution of the impaction

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

may be expected to occur to a significantdegree when the cyst is marsupialized , andseveral truly remarkable cases have beenreported in the lite ratu re (Feam e and Lee,19t18; Sain ct a t 1992). Treatment by enucle­a tion will resu lt in inco mplete removal o f theepithel ium, aro und the neck of the too thcrown, or accid en tal d islodgemen t of thetoo th during the cu rettage p rocess.

It would be naive to su ppose that all casesw ill be corrected so completely, without veryconsiderable a nd ex tensive additional mech­anotherapy. The crown of the too th is full yex posed w ithin the cystic cavity. and its sur­ro unding pe riodontal attach me nt is veryru d imentary an d weak. In larger cysts, mar­sup ialization will slowly allow the bone toregenerat e an d to repair the large d efect th atthe cyst has created . The repair occurs slowly,an d the too th will be in the va nguard of thi sprogress. Any attempt to ,lpply orthodontictraction to the too th at this time will extrude itahead of the ad va ncing bone, thereby weak­ening its bony an d period ont al sup port andp rejud icing its longevity.

It must be concluded that the cyst must betreated first and that it is then importa nt tofollow up the hea ling p rocess until the ho nehas completed the reparati ve fill-in of thebony d efec t. O nly at that point, wh ich will bemany mon ths la ter , sho uld an assessment bemad e of how mu ch improvement hasoccu rred nat urally, ho w mu ch more may beexpected, and how mu ch orthodontic treat­ment is needed to im pro ve the p ositions ofthe teeth . It is unl ikely tha t such treatmen twill make u p for any residual bony defect,an d, for thi s reason , patience is ad vised, inorder to take advantage of the max imum nat­ura l poten tial for alveolar bone repair. The reis therefore no value in bonding an attach­ment to the too th at the time tha t the marsu­p ialization is u nd ertaken initially .

Wh en enucleation, ra ther than marsupial­ization, of the cys t has bee n performed, thehealing process will leave the affected toothwhere it is - o ften gros sly disp laced fro m itsproper pla ce in the arch. Fu r thermore, withthe lining of the cyst remo ved, th e large bonydefect will fill wit h blood clo t, whose undis­tu rbcd rco rgantzanon will bring about hea l-

OTHER SINGLETEETH 175

Ia)

Cd l

(bj Cd

'el

(fI

Figur e 7.17

(a-cJ Maxillary first premolars had been extrac ted by another pr actitioner ', to ,111,,", S1',K1.' for eruption of theunerupted rightlateral incisor' . Note the relative lack of ve rt ical development and tipping of ,l(1~l ""l1 t tooth , rt'mi I1i.~..en tuf an assooatton with lnfruocclu siun. (dl ThO;' pr e-su rgica l periapical ra di ographic view. (O;') Fo llow ing or th odontic spaceR'g" i nin~, sur~ical expo"ure reveals the cervical resorption defect. Soft resorption-replaceme nt tiss uO;' h"d prevent ed theuruphon. ({) The re-orphon area was debrided , an d the exposed pulp exti rp a t,'d an d ro..rt-filled ternporartly w ith cal­cium hydroxide. Aftc r ,111\,l lg.1m restora tion placement, an eyelet was bondc<d and im mc-di.l te nacnon applied. (gl Th..fina l ..t,llol"'S ..,f ,·mpti..m mechanics. (h- j) The completed orthodontic res ult, a fte r d efin itive roo t canal therapy was com­pk-tod an d ,1 porcelain crown pl,K1.-d. Ik.l) The clinicaland periapica l radiographic views of the t.....uh.

(Fig ure 7.17 (Imtjllln, /)

176

(Figu re 1.17 co" f irmedl

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(h ,

(k'

(i) (jl

(I)

Ing, by primary intention. To achieve thisgoal. a complete and hermetic closure o f thesurgical flap w ill be at tempted . to p ro tect thewound from in fectio n . The surgeon will p re­fer not to run the risk of in trod ucing infection,which could track alo ng a s tai nless s teel liga­tur e wire tha t is ligated to an atta chment onthe im pacted tooth, when the wound is a rela­tively large one. It wou ld be preferable towait for hea ling to occu r and then to re­expose the too th on a much sm aller an d morelocalized sca le. However, following this sur ­g tcal p roced ure, spontaneous impro vementa fter its position h,15 im pro ved may be slig ht ,and ,1 too th, grossly d isplaced by such a cyst,may remain in an u ntenable position, follow­ing filling-in of the surrou nd ing tissues .

From the point of view of the oral and max ­illofacial surgeon, treatment of this cyst is apriority - often for no reason other than to

confirm the relatively innocent diagnosis. Itm ust be remembered that, u ntil a biopsy andpathological inves tigation are perform ed , thed iagnosis is on ly tentative. While the moresinister alt ernative diagnoses arc fortunatelyrare, the surgeon cann ot take the chanceinvolved in delay ing th e performan ce of thenecessary d iagnostic procedures u ntil thepatien t is read y to accep t or thod ontic treat­ment. From the orthodontic p oin t of view, thepatien t sho u ld be prepared for treatmen t,with an un d erstand ing of the demands o f oralhygiene, the need to wear appliances and theneed to expose the im pacted teeth. Theserequirements may of ten be fulfil led quitequ ickly, bu t it is u nfair to coerce pa tien ts in toa hu rried decision before they arc read y, andit is usually counterproductive.

It would be logical to infer from this discus­sion that, although the orthodontist h.15 much

B I 8UOT~~"" J I': n o:; L'IJ~"\I~~SIT~DO;: rt ;:1 ": v

U .F .R. D'C ;"} :-: ~lrOl0C1E:

1, rue ! ': =, u riC 'J ·:, rno~·x

OTHER SINGLETEETH

to con tribu te to the outcome of the treatment,this contribu tion relates to the latter s tagesand not to the immed iate prospects. It wou ldtherefore be wise to include the orthod on tistin the decision-making team, bu t inap prop ri­ate for him or her to beco me involved in theea rly s tages of treatment in any active man­ne r, u ntil much of the bony fillin g-in hasoccu rred and the too th has migrated downahead of this.

REFERENCESAzaz B, Sh teye r A (1978) Resorp tion of thecrown in impacted maxillary canine. A clini­cal, rad iographic and histologic study. lilt]Oml Sltrg 7; 167- 71.

Becke r, A (1977) The correction of mesiallyangula ted semi-impacted mola r tee th by sim­p le orthodontic means. lsr ] Dent M l.'d26(2), 17-22.

Becker A, Kamct-R'em RM (1992a) The effectsof infraocclu sion: part 1 - tilting of the adja­cen t tee th and space loss. Am / Orthod102: 257-64 .

Becker A, Kamei-R'em RM (1992b) Theeffects of infraocclusion: part 2 - the type ofmoveme nt of the ad jacent teeth and th eir ver­tical development. A m / Orthod 102; 302-9.

Becker A, Karnei-R'em RM, Steigma n 5(1992c) The effects of in fraocclusion : part 3 ­d ental arch leng th and the m id line. Alii !Orthmi 210: 427-33.

Becker A, Shochat 5 (1982) Submergence of ad eciduou s tooth, its ramifications on th e d en­tition and treatment of the res ulting malocclu ­sion. Am ! Ort/lOd 81; 240-4.

Blackwood HlJ (1958) Resorp tion of enameland d en tine in the unerupted tooth. Oral SlIrgOral Ml'd Oral Patl, 11: 79--85.

Brezniak N , bcn-Yehuda A, Sha plra Y (1993)Un usua l mand ibu lar canine transposition: acase report. Am / Orthod De1Itofae Orthop104: 91-4.

Fcarnc 1. Lee RT (1988) Favourable sponta­neous eru ption of severely d isp laced maxil-

lary canines with associated follicu lar d istur­bance. Br / Orthoa15: 93-8.

Kohavi D, Zilbe rman Y, Becker A (1984)Period on ta l status following the alignment o fbuccally ecto pic maxillary canine teeth. Am /Ortl/Od 85: 78-82.

Ku rol J (1984) Infraocelusion o f primarymolars. An epidemiological, famili al, longitu­d inal, clin ical and his tological stud y. SteedDent J21 (SII/'l1l): 1-67.

Kur ol I, Thiland er B (1984) Infraocelusion ofprimary ma IMS and the effect on occlusald evelopmen t, a long itu d ina l s tudy . Eur /Orthod 6: 277- 93.

Majourau A, Norton LA (1995) Upr igh tingimpacted seco nd mola rs with segmen tedsp rings. Am / Or/hod Dm tofa e Or/hop107: 235-8.

Pro ffit WR (1992) Contemporary Ortlwdolltics.Mosby Year Book , S1. Louis.

Proffit WR, Vig KWL (1981) Primary failureof eru ptio n: ,1 possible cause of posterior openbite. Am / Ort1lt~t 80: 173-90.

Raghocbar, Jansen HW, Iongcblocd WL,Boering G. Vissink A (1992) Secondary reten ­tion of permanent mo lars: an assessment ofankylosis by scanning elec tron and lightmicroscopy. 8r / Oral Maxillafae SlIrX30: 50-5.

Richa rdson ME, Richa rdso n A 0 9(3) Lo werthird molar d evelopm ent subsequent to sec­ond molar extraction . Am J Orthod Dl·"tofaeOrtllOp 104: 566-74.

Sain DR, Hollis WA, Togrye A I~ (1992)Correction of su periorly d isplaced impactedcanine du e to a large d en tigero us cys t. Am ]Grmod Delltofne OrtllOp 102; 270- 6.

Shafer WG, Hine MK, Levy BM (lY H3) ATl.'xtlltltJk of Oml PatlJo!oxy, 4th ed n. WBSau nders, Philad elphia.

Stagge rs JA 09Y0) A comparison of result s ofsecond molar and first prem olar extractiontrea tmen t. Am / Ortnod Dt'1Itafae Ortllo,'98; 430-6.

Wilson HE (1966) The extraction o f second.permanent mola rs as a th erapeutic measu re.Trans Enr Ort//Od Soc 42; 141- 5.

8 IMPACTED TEETH IN THE ADULTPATIENT

CONTENTS • Neglect and di sg uise • Management • The need for temporaryprostheses during tre atm ent • Supp lementary clin ical concerns • Temporary prostheticrep lacement and tooth tr ansposition • The unerupted th ird mol ar as a potential br idg eabutment • Implant anchorage

NEGLECT AND DISGUISE

A sma ll bu l significan t number of untreatedimpacted teeth will eventually find some wayof erupting in to the mouth - ,..-ithou t trea t­ment - although this may be ma ny yea rs aftertheir normal eruption time, and then ofteninto a n ectopic eru ption site. Th is is par ticu­larly true of maxillary canines (Thtlander andJacobson, 1968), and in d irect contrad iction ofthe po pular view that eruption po tential islost w hen the root apex d oses (Kokich andMathews, 1993). Nevertheless, a good propor­tion will remain unerupted and as ym pto­matic for many yea rs. Pros thetis ts ar e allaware of the occasional patient com plain ingof the eruption of a tooth und er a den tu re,often many years after the pa tient hadbecome o the rw ise ed entul ous.

For the most par t, d uri ng the childhood ofthe pa rticula r adult pa tient concerned , ad vicewas probably sough t and rejected , with thereasons fo r this being very varied . The patien tmay have been an orthod ontically unm anage­able child at the appropri ate age; perhaps thedentist or orthod on tist was insuf ficientlv con­vinci ng in the task of infonning the pa ren t ofthe consequences of non-treatment ; or the

parents' level o f denta l a war eness was inad e­quate, the id ea tha t surgery wou ld be neededwas possibly abhorrent to the paren ts, or sim­ply the cos t and d uration of the proposedtrea tment were unacceptable. Just occasion­ally, a surgical exposure p rocedu re will ha vebee n carried out a t the appropriate time, havefailed to elicit eruption and was not then fol­lowed up. Some impacted teeth, particu la rlymaxillary canines , may simply never havebeen d iagnosed . One fu rther poss ibility tha tis not unfamilia r is that a dentis t succumbedto the plead ings of the parent to 'do so me­thing tem porar y to make-it-look-good'. untilthey would be ready for the definiti ve treat­ment - a tim e that never arrived!

It may be diffic ult for the orthodontist toimagine the sit ua tion wh ere a pa tient hasreached ad ulthood with a central incisor stillimpa cted . This will have bee n obvio us fro maround the age of 7 yea rs, bu t the pa tient on lysought treatment in his / her twenties o r, pos­sibly, evenla ter. This type of neglect is indeedunusual, and its p revalence seems likely tovary from cou ntry to country, in inverse p ro­portion to the level of dental awareness in thepo pulation. A country that offers its citizenssome fonn of national den tal insu rance may

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH180------- - - - - - - ------- - -

(., (b,

Figure 8.1

Impacted right m.lKilla ry central inciso r (al replaced by poorly matched arti ficial tooth on 'flipper' (spoon) dentur e (b).

be expected to have a lower prevalenceamong its adults, since one woul d hope thattreatment would have been car ried ou t at theappropria te time, given the relative freedomfrom financial constrai nts in a welfare state.Cost, however, is not the only factor andprobably not even the dominant one.

Whatever the reason, however, the adultpa tient will usually present with the incisoranomaly un successfu lly d isgui sed in one ofthree ways.

1 A retained deciduous tooth may havebeen enlarged with the ad d ition of com­posite material, althou gh this w ill prob-

Figure 8.2

Impacted right maxillary central incisor . The right lateralincisor crown has been enlarged by a com posite build­up.

ably have improved only its leng th.Any increase in its width will be limitedby the red uced mesio-d ista l space avail­able to the tooth, the res ult of the markedmesi al tipping of the adjacen t lateralincisor and the cen tra l incisor of theopposite side.

2 This reduced space may hav e been main ­tained wi th a 'flipper' (spoon) partialdenture, carrying a single and poorlymatched small tooth (Fig. 8.O.

3 The latera l incisor ma y have beenenlarged, with the use of composite mate­rial in an attem pt to simulate the shape ofthe impacted cen tra l inciso r <Fig . 8.2).

IMPACTED TEETH IN THE ADU LT PATIENT

There arc serio us d rawbacks with each ofthese treatm ent alternatives, which focu sprincipally o n the very poor appeara nce ofthe resu lts. The absence or red uction in size o fa cen tral inciso r is always obvious, as too isany significant shift in a max illa ry dentalmid line, even to the casua l observer. The tip­ping of the two teeth adjacent to the im pactedincisor is too severe to esca pe notice, an d theangle o f the latera l incisor is too acu te for itslong axis to be visually ' realig ned ' by com­posite additio ns or by reshaping. The narrow­ness o f the neck of the tooth makes anaes the tically convincing reco nstruction as acen tral incisor im possible.

MANAGEMENT

It is quite clea r tha t, under these circum­stances, the first and mos t important prereq­u isite to any form of trea tmen t for the missingtooth is to p rovide the maxilla ry dental ar chwith an ideal shape in each of the three planesof space. In practical terms, this means thefollowin g.

1 lr1.'t'//iIlKand alignillg li't' entire dell tal orcti .All ectopi cally p laced teeth will need tobe brought in to an ideal ar chform, teethwill need to be aligned in a single, un i­form occlusal pla ne an d all rot ations dealtwith.

2 Reopen ing a space of euitabtc II/csio-dista/width iu order to occowodate the impactedtootlt i ll t!le arch. Co rrecting the pala talinclin ation of the canine and tipping thelatera l inciso r of the same side and thecen tra l and lateral incisor of the oppositeside will usually provide adequate space,although d ista l movemen t, extraction orint erp roximal enamel st ripp ing may needto be considered.

3 Correcting lI,e dt'lltal midline to be continu­OIlS with tilt' touxr 111/11 with file midline of theface. This is normally ach ieved as a res ultof the reopening of space, but it mayreq uire the usc of coil sp rings or an terior,oblique, in termax illary clas tics as part of

a. more com prehensive orthod ontic appli­an ce program me.

4 Closing dowll all anterior O/'t'll bitt' andbrillgillS tilt' tedll into oc clusion, This isp robably best achieved by properly align­ing the molar tubes a nd by alteringbracket height on the anterior tee th,thereby bringing abo ut the desired extru ­sion of the tee th. However, a nteri or verti­cal elas tics are of ma terial help in thissituation .

Once these aims have been achieved , thepatien t is read y for that stage in treatmentwhen all resources w ill need to be concen­trat ed on the im pacted too th . The en tiredental arch must be consolidated into a com­pound and united anc horage unit, to whichthe unerup ted too th will be d rawn .

In Chapters 6 and 7, we mentioned thatteeth tha t have been impa cted for many yearssometimes undergo pa thological change thatprevents their eru p tion (AZ.1Z and Shtcycr.1978), even when all other factors arefavourable. It is by no means always possibleto d iagnose pa thological change from a rad i­ograph, unless there is a loss o f the follicu larsac and actual enamel resorpt ion has becomeevident over wide areas of the su rface of theun erupted tooth. It is therefo re true to saythat, whenever an adult pa tien t presen ts forthe trea tment of an im pac ted tooth, a calcu­late d risk is taken in offering th is kind oftreatment to resolve the impaction.

In the most ad verse of circumstan ces, thecentral incisor too th w ill have to be extractedan d perhaps su rgically reimpla nted . In tha tevent. the preparation of the dental ar chdescribed abov e will have provid ed optimalclinical conditions to accept the implant orother form of artificial res tora tion of thespace. An ideal po ntic width is present, allother teeth arc alig ned and the occlusion isgoo d. However, the su rgical removal of agrossly displaced impacted too th, high aboveits no rmal position , will leave a. cons iderableand unsightly bony defect. This will be d iffi­cu lt to conceal in the g ing ival area around afixed pros thesis, a nd will not lend itself tothe placing of an Impla nt withou t suit ab leand prior osseous ridge rec onstruction

'"

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH182________ _ ____=-=----= =-=----=.::..=-='-'=c-=---

(Sailer, 1989; Richardson and Cawood, 1991;Sim ion ct al, I1J92; Lus tma nn and Lcwinstein,1995).

The patient m ust be brought into the d eci­sion-ma klng process from the outset andsho uld be infor med of the po ten tial ad van ­tages of each of the stages of the treatment.Prognosis for the success of the pre-surgicalst ages of the trea tment is excellen t, but it isnot so certain for the alignment of theimpacted too th . Offering the treatment planto the pa tient is therefo re p robably bes tacco mplish ed if it is based on explaining thebenefits of the limited objectives. i.e. aligningthe teeth for the pu rposes of achievingImproved cond itions for the construction of aconvent ional prosthod ontic o r imp lant-bo rn ereplacement. The added bonus that will bed eri ved from success in the resolution of theim paction may then be properly brough t in tope rspec tive to provid e the d esirable add edincentive.

By wha tever mean s the value of the treat­men t is explained. ca re sho u ld be taken tofu lly inform the pa tient tha t the possibility offailu re to bring the im pacted tooth into thearch is rea l. bu t that contingency p lans arcavailable in this d isap poin ting eventu ality.

THE NEED FOR TEMPORARYPROSTHESES DURING TREATMENT

tomcd to it, even if its retention is ini tia llyadequa te. Of great er con cern , ho cvever , is th efact that the ad jacent teeth and many othersneed to be moved d ur ing the or thod ontictreatment, whic h will rapid ly make this a rtifi­cial dentu re ill-fitting. Fu rthermore, its adap­ta tion to the con tour of the other teeth in thejaw may actually interfe re with the p lannedor thodontic move ment.

For this type of art ificial replacement to besuccessful, Ad ams' clas ps ma y have to beused o n the second mo lars, or, altern atively, amodified circumferential clas p may hoo kover the bu ccal tubes of the first mo la rs.These tee th are often excl ud ed from theplanned dental movements, and ma y so me­tim es be helpful in reta ining such a plate,alt hough the d ista nce between the clasps an dan incisor pon tic may be th e cause of an unac­cep table degree of ins tability.

Clearly, more sa tisfactory alterna tive meth­ods of artificial replacement are essential tothe successful pursuit of treatm en t for theadult pa tient, an d these mu s t provide ananswer to the several sho rtcomings of the'flipper' dentu re . Indeed , given a littlethought in their d es ign and rather than theirplaying the role of the villain of the piece,assistan ce may be d erived from the method ofartificial replacem ent, w hich may contribu teto the ope ration of the active orthod onticapp liance.

For the ad ult patient , planned orthodonticspace -open ing for an uneru p ted anter iortooth is a dau nting prospect. All central andlateral incisors and many ma xillary can inesrequ ire some form of immed iate temporaryprosthetic replacement until such time as thepermanen t tooth comes in to its place. Withsome patient s. particularly those more con­cerned wit h th eir appl'aran ce, or those whohave a broader smile or a wider dental dis­p lay that is evident in facial expression an dsocial intercou rse, there may be a need to arti­ficia lly rep lace even p remolar teeth .

If the artificial res toration ta kes the form ofa removable pla te carryi ng a sing le tooth, a'flip per' (spoon) dentur e, the pa tient mayhave considerab le d ifficu lty becoming accu s-

The active removable plate

If a rem ov ab le p la te is to be worn to hold th eartificial too th in pla ce, it makes good sense toau gment that pla te with active elements thatwill also produce tooth movement. Looked atin a d ifferent way, this means the designingof a simp le removable or tho dontic ap pliance,carrying sp rings of one sort or another thatarc aimed at realign ing the teeth to reopen theant er ior space an d , at the same time, to fillthat space with an art ificial too th.

This method has so me importan t ad van­tag es . The act ive p la te is s tra tgh forw ard an deasy to use, requ iring very limited ex pe rtise

IMPACTED TEETH IN THE ADULT PATIENT

in its adj ustment of the forces applied and intheir d irection. The artificial tooth may be eas­ily altered in size as space-opening occurs, tomain tain appea rance.

However, the active removable appliance isunab le of producing more than tipping move­men ts of the ad jacent teeth. Methods ha vebeen described where a removable appliancehas been used to produce the extrusive move­ments needed to reso lve the impaction ofteeth <Fournier et al, 1982; Orton et al, 1995).Its effectiveness in this capacity is limited ,and it cannot be expected to perform labio­lingual or mesio-d ista l root movements orrotatory movements that are often needed tofully align these aberrant teeth. Therefore incases where rem ovable appliances are used toreso lve the initial impaction and to erupt thetooth, they must be followed by a fixed appli­ance to bring about the successful completionof a second phase of the treat ment, which isaimed at the fine positioning of the teeth in allthree planes of space.

The soldered palatal arch

In the ad ult patient, the scope of or thodonticcorrection that is planned tends to be morelocalized and less comp rehensive, particu­la rly when a single and grossly displacedtooth is present. Accordingly, the first maxil­lary molar teeth are most commonly usedas ancho r teeth for the fixed appliance, andtheir orthodon tic movem ent is not usuallyrequ ired . This being so, the buccal aspects ofthese teeth and buccal/ labial aspects of theteeth mo re anteriorly placed will be used tocarry the orthodo ntic brackets, archwires andau xiliary. This leaves the pa latal side of theteeth and the palate area free and available toserve the interests of the patient' s appearance.

The missing central incisor

A soldered pa latal arch, based on the molarbands, can provide a n orthodontic a ppliancewith a n excellent anchorage base, a t the same

time as acting as the vehicle for a sa tisfactoryprosthetic replacemen t. Several approachesare avail able, and they depend on the ada pta­tion of well-fitting preformed ort hodonticbands to the molar teeth a nd their accuratetransference to a plas ter working model of thejaw.

On the working model, a palatal arch isfabricated and soldered on the pal atal side ofthe molar bands. A small wire extension maythen be soldered or bent into the anterior por­tion of the palatal arch, extendi ng towards thespace in the arch and terminating immedi­ately palatal to the position of the missingtoo th, with a configuration that will mechani­cally retain an ar tificial acry lic tooth. Theexact location of the artificial tooth should bedecided in accordance with the projectedtreatment goals of the case and not ncccsse r­By in line with the adja cent nat ural teeth.Thus, if an overjet is to be closed or a cross­bite treated, the siting of the artificial toothshould be made according to the intendedfinal, post-treatment , position of the adjacenttee th. An occluded plaster cas t of the oppositejaw is therefore necessary to assist in its accu­rate placement.

This is the Simples t app roach of th is typeand it offers the pa tient a good artificialreplacement, which is well tolera ted (Figs8.3a,b). It also allows the ad jacent teeth to bealigned withou t hind rance, while actuallyenhancing the anchorage value of the molarsdu ring ret raction of a procumbent labial seg4

m erit. The anchor molars cannot be rotated ortipped easily wh en using ho rizontal , in tra­maxillary, elastics, ow ing to the stabilizingeffect of the rigid soldered pa latal arch.

A significant and valuable refi nement ofthis appro ach involves bonding o conven­tional bracket to the artificial tooth, as withthe o ther teeth . This makes the artificial toothaesthetica lly compro mised to a similar degreeas the other teeth an d therefore less recogn tz­able as other than a part of the natura l denti­tion. Since this too th is rigid ly a ttached to themolar teeth and at a fixed d istance from them,this method has much more to offer . Its inte­gration in to the appliance sys tem ma kesalignment and levelling more accurate andmore rapid . Ad ditiona lly, the need for elas tic

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH184----------------------

(.J

Figure 8.3

(a) Same patil'nl as in Fig. 8.2. to show initial stages ofal igomeot and ..pan- opening. The com posite build­up of the maxillary rightlatera l incisor is still in place.(b) Space has been reopened. the composite build-u pof the lateral incisor has been removed, and the artifi­cial cent ra l incisor is in place, at tached to the solderedpala ta l arc h.

(bJ

traction to reduce the overjet will be elimi­nated, since the use of the init ial fine-gaugeand ideal archforms in the early weeks oftreatment will perform this without any fur­ther modi fication . The distance and relation­ship between molars and the artificial incisoris fixed to the Ideal length and position by thepalatal arch. Thus a progression of ideal wirearchfor ms will align all other teeth with inthat a rch. Essen tially, by linking the ar chw ireto the fixed pontic, in its norma l overjet andoverbite location, the firs t stage of mechan­otherapy. which generally deals with initiallevelling and alig nment onl y, now comes to

include automat ic overjet and overbite reduc­tion .

The overall length of the heavy palatal archprovides it with a degree of ela sticity, desp iteits heavy gauge. Thus, wh ile carrying a tem­porary prosthet ic replacement, it may be usedto widen or co nstrict the den tal arch. In thepresent con text, however, it has one otherpossib le function, which is less obvious, bu tmost helpful. The palatal arch has the poten­tial to p rovide the vertical componen t o f forcethat is needed to close a n anterior open biteand subsequently the vertical traction neededto resolve the incisor impaction (Fig. 8.4).

IMPACTED TEETH IN THE ADULT PATIENT

Cd

Cd '

Figure 8.4

Closi ng the an terior open bite, in the sa me pa tient as inFig. 8.2. (al The so ldered arch has been d eflected s lightlyvertically downwards to elongate the artificial tooth. (bJPlacement of th e archwire shows the deg ree of verticaldisplacement. The artificial toot h is now full y engaged inthe archwire. (e) The extrusive force of the pala ta l arch­wire clUM'S off th e ope n bile . (d ) The periapica l viewshows the impact ed too th to be dil aa:rated. The palatalarch Is clear ly seen, wit h the Iorward-poinung loop usedto carry the radiolucen t arti ficia l tooth. An orthodonticbrack et is also attached to this rad io log ically invisibletooth , (e ) pre-treatment tangenitia l radiograph. (0

Bonding of an eye tetto the ana tom ica lly pala ta l aspect ofthe incisor cro w n, (g) The elas tic chain is gen tly raisedand ensnared in the pigta il to provide immediate andcontrolled vertica l traction . (h) Post-surgica l periapicalview to show the bonded eyelet and pig ta ils ligat ure , (i)

The tangenti al view pos t-surgery. ,.,howing the leng th ofthe unseen part of the ligature an d the relative heights ofthe tooth, the ligature ext remity and the occlusa l plane.(j) The impacted tooth has erupted 5 mo nths lntcr : notethe red uction uf the cervical po rtion vI the artificialtoothto allow for furthe r progres s. Traction was mode to anewly placed labia l a ttachment a t th is juncture. (k)Periapica l view of the dila ccratc incisor a t the completionof treatment. (J) The orth odontic result : no te th e gingi valappearan ce of the tre ated and untrea ted maxillary cen tra lincisors .

(Figure 8.4 amlillllrd l

Ie)

,.,

r

-

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH

'h'

(i) IV (Figu re 8.4 colltinurd )

IMPACTED TEETH IN THE ADULT PATIENT

(Figu re 8.4 COl lf i ,med )

(k!

The missing maxillary canine

Aside from third molars and in common withthe youn ger pa tient. the too th most fre­quently fou nd to be impacted in the ad ult isthe maxillary canine. The principles of d iag­nosis, treatment planni ng and appliance ther­apy in the adult arc no different from those ofthe child, although certain demands are madeby the adul t pa tien t, wh ich may make trea t­ment met hods less routine and more individ­ualized . However, the du ration of suchtrea tment in the ovcr-zy-ycar-old age grou p islikely to be sign ificantly longer than for thechild pa tien t (Herzer et al, 19(4) .

In a case wit h Impacted incisor teeth, the

187

presence of a palatal arch does not encroachon the area where surgical exposure and post­surgical swe lling arc likely to occur, pro videdthat the anterior po rtion of the palatal arch isnot brought too far forwa rd . A 'cut-back'des ign is usually mos t appropriate. In orderto expose a palatally dis placed maxillarycanine, a wide area of pala tal mucosa mayneed to be reflected back, and this, togetherwi th the possible sequel of even a minimaldegree of post-surgical oedema, effectivelyd isqualifies the usc of a rigid pala tal arch inthese circumstances.

A trans-palatal bar, such as a Coshgar ian ora simple 'across-the-p alate' soldered arc h, areusually sufficien tly distan t from the surgical

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH188 ...::..:=-=-...::..:::.::..:'-----=----=:::.::..:...::..:=--'-----'--'' '---

site to be used in these circu mstances. Theycanno t be used for prosthetic replacement ,and their only function is to enhance theanchorage. However, in combina tion with abuccal arm, they may be very useful and havedefinite indications.

In the cast' illustra ted in Fig. 8.5, theadapted mola r bands are transferred to aplaster working model and a transpalatalarch is soldered to the palatal side of thebands . Molar tubes are welded to the buccalside of the bands, and , gingival to these tubes ,a heavy bucca l arm is so ldered, ex tendingvertically upwards into the sulcus. The arm isthen fabricated to follow the depth of the sul ­cus anteriorly until it reaches the canine area,where it aga in dips inferiorly, to terminate ina loop in the canine site. An artificial acry lictooth is cured. into this retention loop, in theplace of the missing permanent canine.

Immediately after extraction of the naturaldec iduous tooth. the unit. which comprisestwo molar bands, a palatal arch and a buccalarm, is cemented into place, followed byappropriate o rthodontic attachments on theot her teeth. After initial alignment and spaceopening, the imp acted canine is exposed sur­gically, from the buccal or palatal side, asapprop riate to the case. Traction may then beapplied in the normal way, bu t carried ou tbeh ind the facade of the buccally retainedartificial toot h.

As with the placem ent of a bracket on theartificial cent ra l incisor, described above, it isadvantageous to design the integration ofthese prosthetic exped ients into the orthodon­tic appliance sys tem in such a way that theymay contr ibu te materially to the efficiency ofthe appliance. Thus, a fter cementation of thebands carrying these add itions, the buccalarm is d isp laced further buccally, so that itspassive position is a few millimetres bu ccal toits original location . If it is now tied d irectlyto the impacted canine, using a steel liga ture,th is w ill realign the di sp laced buccal arm an dartificial too th. The energy sto red by this longa nd elastic bu ccal arm will now provide thetrac tion needed to draw the impacted too thtowards its p lace in the arch.

SUPPLEMENTARY CLINICALCONCERNS

The basic premise for the use of thesepalatal and buccal ar ches has been that thefirst molar tooth does not require to beor thodontically moved. Needless to say, thereare cases in which movement of the firs tmolars is an essentia l pa rt o f the orthodonticstra tegy of the treatment of a particular adult.These may include cases where there is a pro­nounced rotation or a palatal or buccal d is­placement of this tooth, bu t they may alsoinclude the premolar extraction cases whereclosure of excess space from the distal will beneeded .

In these cases, several options are still avail­able to allow the smooth pursuit of orthodon­tic treatment In the first place , a singlebuccally or palatally displaced molar tooth,w hich it is p lanned to use as an anchor unit,may be tip ped into its place using a remov­able applia nce . This appliance will need tocarry some form of buccal or palata l spring,which will be used to move the too th in theappropriate direction, su itable clasps to retainthe applia nce firmly in posi tion, and , possi­bly, an artificial tooth to replace the impactedincisor tooth in the interim. Alternatively, anexisting 'flippe r' denture may be aug mentedto inco rpo rate the same clasp an d spr ing ele­ments.

When more extensive movement of theanchor tee th is req uired, th is is us uallyenacted in a prepara tory orthodonti c trea t­men t pha se, w hich is aimed at producinggood alignmen t by uprighting, ro tating andtorq ueing the teeth, whil e limiting the appli­an ce work and movement of the anteriorteeth to levelling and aligni ng. Du ring thisprocedure, it is importan t to enable thepatien t who has bee n wearing an artificialdenture to continue to do so un til such timeas the alignmen t stage is complete. Similar ly,an over-re tained deciduous inciso r too thshould be allowed to remain un til theplanned tempora ry pros thetic rehabilitationbecomes practical. With the sa tisfactory com­pletio n of the prepara tory orthodontic treat­ment phase and the tee th having beenbrou ght into good alignment. the precise

IMPACTED TEETH IN THE ADULT PATIENT

(,)

(d

(c )

(b )

(d)

If)

Figure 8.5

(a-e) A 47-yt'ar-old female has a maxillary left canine that is impa cted adjolCt'nt 10 ,1 pvg-Sh,l f....-d latcru l inciso r. Theerupted right canine is in the place of the congen ilillly abst'nt lat",rill in6",,'r. (d) The p,lt il'nt Wl'.1I'" ,1 removable partialplate to fill the canine sill'S on each side, (e-g) The molar bands arc in\l'rc onnl'C!I'l.I by ,1 soldered 'across-the-pala tal'heavy arch (nol Sl.'l'n). A high buccal ar m is sold ered on each molar band, car rymg an artificial canine too th, to replacethe disc arded pout i"l plat e. (h) A small hook is cured into the left artificial can ine, and the buccal arm is deflec ted buc­cally and inferiorly at the time of su rgicalexposure of the impacted canine. (i) Ligating the impacted tooth 10 the ar tifi­cialtou th applil~ extrusive and buccalt raction. (j-I) The left cilnine has been brought into its place, and a fixed partialprost hesis fills the golp on the ri~ht side. (l'igure 8.5 CQll t i ll Ul'd 1

190 THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(Figure 11.5 cpu/;m/l·,/j

( i) lp

(~ (I)

IMPACTED TEETH IN THE ADULTPATIENT

reope ning o f the space for the missing too th isundertaken .

At this poin t, the palatal arch is const ru ctedon a plas ter mod el, into which the molarbands have been accu rately seated and th eart ificial too th sited, as d escribed above. Thepatient' s dent ure is now d isca rded or theover-retained d eciduous too th is extracted,and the palatal arc h ca rrying the arti ficialincisor too th is inserted by rece rnenti ng themolar bands to their form er place.

When moving tee th mesic-distally along anarchwi re with a multibrncketcd fixed appli­ance, the establishment of interproximal con­tac ts between the teeth enables a hig h d egreeof co ntrol of ind ivid ual tooth position . Oncethis has been achieved, uprighting andtorqucing movements may be carried out ,wi th care being taken to see th at the spaces d onot reo pen. The d esired treatment resultincludes dosed contacts.

In the situation where a tooth is uneru p tedand space must be made for it , the orthod on ­tis t should err on the side of reo pen ing excessspace an d then ma intaining it until the too threaches its p lace. However , to d o so, the spaceneeds to be maintained du ring the ma ny fu r­the r months of treatment, when the adjacentteeth will be alterin g their relationships to oneano ther. While attentio n is d iverted to thedetails o f the treatme nt in these other areas,changes may inadvertently alter the space.The orig inal co il spring , whic h may haveope ned the space, must be de-activated , sinceit will otherwise con tinue to inc rease thed imensions of the space. However, th e p lace­ment of acti ve root-upright ing springs willtend to close th e spncc by compress ing thespr ing .

The size of the artificial incisor tooth and itsmesio-d istal siting mny be very usefu l inhold ing the ach ieved space and in ideallyplacing the adja cen t teeth, regard less of theirlocations and wit hou t the need for the coilspr ing or the ligation o f grou ps of teeth . Thenatural teeth nrc swif tly broug ht into inter­proximal co ntacts with the artificial too th andwit h each other, and this status is the n simpleto maintain.

191

TEMPORARY PROSTHETICREPLACEMENTAND TOOTHTRANSPOSITION

Rarely, one or more of the im pacted tee th isalso trans posed. For the most pa r t. it is prefer­able to align the teeth in thei r transposed.positions, rather than to try to retransposethem to the ir ideal positions, for reaso nsalready d iscussed in Chap ter 6. Nevertheless,there are situations in whic h th is may be thep referred line o f treatment.

Given the hig h fn..'quency of m issing lateralincisors in cases of transposi tion of maxillarycanine/ first premolar transpos ition (Peck etat 1993), treatment of the transposition mayhave to consider the artificial replacemen t ofthe missing teeth during the ap pliance ther­apy. The use of a pa latal arch to augment th eanchorage value of the molar teeth and toprovide the vehicle for the artificial replace­me nt teet h is an effective way to d eal withthis problem (Fig. 8.6).

By tying in a lab ial archwire from mol ar tomolar, passi ng through a bracket on each ofthe ar tificial lateral incisors, these strategicpoints on the perimeter of the arch aredefined in relation to one ano the r, since theincisor pon tics are also rigid ly fixed to themolar ba nds on the lingual s ide. The sma llsection o f lab ial arc h wire tha t intervenesbetween molar tube and incisor bracke t istherefore we ll supported in terms of anchor­age, and may be used to slide the mo re bu ccalof the tran sp osed teeth (usuall y the canine) inthe mesio-di stal p lane. At th e same time , themore lingua l of th e transposed teeth must bemoved fu rther lingually to allow its partnerto pass by. Finally. it mu st be moved in theopposite m esio-d is tal d irection and back inthe line of the arch .

To achieve this, the mo re lingual tooth maybe liga ted to several di fferen t and strateg i­cally plan ned loops and cross-p ieces, whichwill have been p repared on the pal atal arc hahead of time, using clastic thread . Onceagain, positive usc is mad e of the palatal archas an integ ral part of the orthodonti c appl t­ance svs tem, and it is nut merely a means ofsupporting an artificial too th. ..

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH192 ~:..::.~==__=____=_~=__=__~__=_=_='__

(a (bl

(d 'dl

(/1

Figu re 8.6

(a-c) A 27.yt"lT-1l1d (('m,llt' with congenitally absent maxillary lateral ind sllN and maxilla ry canine/firs t premol ar bilat­eral tran spos ition . The d eciduous cani nes and right late ra l incisor art' still present. (dl Occlusal view of rnoxillary ;:m:h.(e-h) Intra-ora l views after extraction of decid uou s teeth. (h-jl Treatment progress. !>O.'CII from th.. right side. (k,D U~ ufpalatal <ITch ,1S suppo rl for late ral incisor punti~ and ab o to move pre mola rs through v,Hying liM' of l'l,htic th read . (ml(\:du...,1 vi..w of complete rnilxiJJilry den tition, wit h wire splin t from fiNl premola r to first pn'mular, including lateralincisor ponncs. In-p) Intra -oral views of the completed orthodontic ....·sult. The F", til'n l WM· refe rred for pe rmanentprost hod ontic trea tment uf the late ra l inciso r probll'm_

IMPACTED TEETH IN THE ADULT PATIENT

(Fig ure 8.6 cOllli ll ll(,11

'gl

(i)

(kl

'h)

(j)

([)

THE ORTHODONTIC TREATMENT OF IMPACTEDTEETH194

--- - - - - - - -----"-'---.....::..::..:--------------------------IFigure 8.6 nm ti ll ued )

--~

In!

(m )

(0) (p)

THE UNERUPTED THIRD MOLAR AS APOTENTIAL BRIDGE ABUTMENT OR ASAN ANTAGONIST FOR AN UNOPPOSEDTOOTH

In th e previous chapter, we d iscussed theuprighttng of molar teeth tha t were preven tedfrom eru p ting, partially or fu lly, by th eir rela­tion ship with an imm edi ate mes ial neigh­bour. It is pertinen t in the con text of thepresen t chap ter to d iscuss a di fferent scenariothat commonly presents.

Following the extraction of posterior tee thin the ad u lt patient , the estab lishment of a'free- end edentulous saddle' makes or alrehabilitation problemat ic. Th is ma y some­times find a potentia lly convenient so lu tion inthe di scovery of an uneru pted third molar.However, the absence of standing posteriorteeth creates mechanotherapeutic d ifficul ties

in providi ng the vertical traction that is aimedat enhancing the eruptive po ten tial of anu neru pted third molar.

Elastic traction of the too th to the opposingjaw is a useful meth od , and has been referredto above (Orton et al. 1995), bu t the use ofremovable appliances in the ad ult patient isunreliable. Adu lts have far greater di fficultybecoming accu stomed to the bulk of the remo v­able pla te and its interference wit h masticatoryand articu lar function . The use of a fixedma ndibula r appliance offers a much more 5..1t­tsfactory and d imensionally mod est alternative,which interferes ne ither with eating nor withspeech . Fur thermore, if the mandibu lar ap pli­ance is to be used onlv as a source of anchor­age, brackets and arch\vircs may be d ispensedwith, making it very inconspicuous indeed .

An unopposed seco nd mo lar in the oppo­site arch is the tooth that faces the poten tial

I,

IMPACTED TEETH IN THE ADULT PATIENT

(,l (bl

•

(d (d l

Figu re 8.1

(a) A 54-ye,u-old male pa tient, showing unopposed ma nd ibular right second mo lar. (b) Close-up views of buccally dis­placed an d partially erupted third molar. (e) A 0.024" round wi re has been ada pted to buccal surfaces of the pre molarand mola r teeth on the man di bular mod el. Note the reten tion loops an d welded mesh pads. The d istal extremity is inthe shape of a hoo k, which has been covered with solder for patien t com fort. ld ) The Lsbaped elastic co nfigu ration forease of place men t an d wide ran ge of act ion . (e) Following eruption , a pa rtially bonded appliance is used to upright thethi rd mo lar . Additional anchorage is derived from a soldered palatal arch from first molar to first mola r. (0 The finalstage of treatment.

THE ORTHODONTIC TREATMENT OF IMPAC TED TEETH196--------- --- - - - -------

(., (b'

'<l «n

(d

Figu re 8.8

Ia.b) An osseo-inl...grak.J impl,]nl h,lS b een placed in the ma\iJIary left second prem olar site. A partially l'ru pil'd anddi ..ta lly lipped th ird molar shows only ils mesial surface and mesia l occlusal cu sps. « l An elast ome ric chain moduleapphcs force 10 the implant post, \';.1 the bo nded eyelet on the mola r. (d) Vertical force is applied tu ,1 mandibula rbo nded buccal ba r, to achieve occlusal con tact. (e) Fully occludi ng third molar . Noll' the use of three bu tto n attachm entsto pnwi de vertical force wi th buccal o r lingual vect ors. as needed. The mesial bu tton is to prevent the ela..tic fromimpinging on the-gingiva. If, g) Pre-an d pos t-treatment rad iographs . (h) Late ra l vicw of IIw prosthodon\ic reconstruc­lion . (Fig ure 8.8 amtil/IIN)

IMPACTEDTEETH IN THE ADULT PATIENT

(Figu re 8.8 roll tilll"~/)

197

(8'

(h )

erup tion site and pro posed final position ofthe un erupted tooth, while premo lars may beocclud ing further for ward . Vert ical extrusionof tee th requi res relatively low fo rce values;nevertheless, it is importan t to include several1I..-cth in the a nchor unit and to rigid ly linkthem together, to prevent or limit their reac­tive extrus ion.

Using a plaster model of the patient' sopposing jaw, a lengt h of 0.024" <0.6 mm)s tainless sIL-e1 w ire is adapted to the generalfonn of the buccal surfaces of the teeth, fromsecond molar to the first or second premolar(Fig. 8.7). The wire extends very slig h tlymesially to the first premolar and a few mil­limeters d istally to the second molar, wh ere itis bent into a hook. Those parts of the wireimmed iately overlying the tooth sur facesshould also include sma ll ret en tion loops, towhich should be weld ed sma ll patches ofstainless steel mesh. These mesh pa ds areadapted to the sha pe of the tooth surface.

Returning to the patient, the buccal sur ­faces o f the teeth are etched and the wirebonded to them, using a composite ma terial.Unfilled res in, such as Poly-C or Directon (TPLabora tories ), is p robably the easiest to use, isadequate for the task, and is easy to removeat the conclusion of the treatmen t. A smallcustom-mad e hook or button is p repa red andbonded to the unerupted tooth, following itsexposure. At the sa me visit as these prcce-

dures are performed , the patient is taug ht top lace a small latex ela stic 0 / 8" med ium or5/ 16" light gauge) on the hook and to d raw itround the wire extension d istally to theopposing seco nd molar and then forward toengage the small protrusion of the wiremesial to the first premolar.

This for ms an L shaped con figu rat ion tothe elas tic, which has a dual purpose. Theoverall length provides for a light force ofexcellent ra nge, while, at the same tim e, mak­ing the manipulation of the elastic very easyfor the pa tient. The vertical traction that isapplied to the tooth may be al tered to incl udea horizontal com po nen t, by al tering the posi­tion of the d istal end of the bond ed wire,thereby also d irecting the tooth mesially, d is­tally, lingu ally or bu ccally.

IMPLANT ANCHORAGE

A successfu l im plant can be used to provide'absolute' an chorage, since it forms an osseo­integ ra ted unio n with the bone, and , like anankyloscd too th, will no t respond 10 ortho­dontic forces (Fig. 8.8). The use o f implan ts inthis manner would appear 10 offer consider­able promise for the fu ture, par ticularly forpartially denta te ad ults, and for replacingextra -oral anchorage in non-growing patients(Roberts et al, 1984).

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH198--- --- --------- -------REFERENCES

Azaz B, Shteye r A (1 978) Resorption of thecrown in impacted maxill ary ca nine . A clini­cal, radiographic and his tologic study. lil t IGml Sf/rg 7: 167- 71.

Fournier A, Turcotte J, Bernard C (1982)Orthod on tic considera tions in the treatmentof maxillary im pacted canines. Am I Orthod81: 236-9.

Herzer W, Seifert 0, Mahdi Y (1994) Diekieferorthopadtsche einordnung rctiruertcreckzahne un ter bcsondcrcr bcruckstch tigu ngdes behandlungsalters, der angulation undder dynamischen okklusion. Fortscnr Kieieror­t!lop55: 47-53.

Kokich ve, Mathevvs Dr (1993) Surgical andorthodontic management of Impa cted tee th .Dellt eli" N Am 37: 181- 204.

Lustmann J, Lewinstein ( 995)In terpositional bo ne g rafting technique towid en narrow maxillary ridge. 11It J OralMaxillo/ac Implallts 10: 568-77.

Orton H5, Garvey MT, Pea rson MH ( 995)Extrusion of the ectop ic maxillary canineusing a lower removabl e appliance. Alii JOrtlwd 107: 349- 59.

Peck L, Peck 5, Attia Y (1993) Maxillarycanine-fi rst premolar transposition, associ­ated den tal anomalies and genetic basis.Angle Grtnod 63: 99-1 09.

Richardson 0, Cawood JI ( 991) Anteriormaxillary os teop lasty to broade n the narrowmaxillary ridge. lilt ] Oral Maxillo/ac Surg20: 342-8.

Roberts WE, Smith RK, Zilberman Y et al(1984) Osseous adaptation to continuousloading o f rigid endosseo us implants. Am JOrthod 86: 95-111.

Sailer HF (1989) Two new method s combin­ing osteotomies and cndosseous tita niu mscrew implan ts for the narrow maxillaryridge and the atrophic lat eral mandi ble. In:Proceedings 0/ Third International Congress 011Preprostnetic Surgery, 'Tile edeniuicus jaw',Arnnem, The Netherlands, 1989, 62-3 (abstl.

Simian M, Baldoni M, za ffe D (1992) Jaw boneenlargem ent using immed iat e implant place­ment associated with a spli t-erest techn iqueand guided tissue regeneration. lilt J PeriodentRestor Delli 12: 463-73.

Thilandcr B, Jacobson SO ( 968) Local factor sin impaction of maxillary canines. Acta OdontScand 26: 145-68 .

9 CLEIDOCRANIAL DYSPLASIA

CONTENTS • Clin ical features and dental ch aracteri st ics • Treatment modal ities• Dental crowdi ng • Retention • The relat ive merits o f the di fferent approaches• Methodo logy o f the Jerusalem apcroech • Treat ment experi ence • Pat ient var iat io n

CLINICAL FEATURES AND DENTALCHARAC TERISTICS

The cleidocranial d ysplasia pa tient is typ i­cally of short stature, wi th a b rachycephalicsku ll a nd bossing of the parietal and frontalbones. There is hypoplasia o f the m td face.giving the misleadi ng appeara nce o f mandib­ula r p rogna thism . The sku ll su tu res andfontanelles ex hibi t delayed clos ure and sec­onda ry centres of ossificatio n occu r in theseareas, with the formation of worm ian bones.The development of the clavicl es is defective,and mngcs from a sm all med ial ga p to totalab sence in severe cases (Kallia la andTasktnen . 1962; Bixler , 1976; Cohen, 1976;Zegnrclli ct al, 1978; Shafer et nl, 19H3;Tachdjian, 1990; God in et al, 1990). Thepa tient usu ally has a narrow ches t and slo p­ing shou lders . Accord ing to Stewart andPresco tt (1976), more th an 100 other enom­alies have been asso ciated with these majorclinica l features in the con di tion.

The pa late is narrow and occas ionally hig h,an d there is no rmal eruption and nu mber ofthe d eciduous teeth. The permanent molarsusually eru pt la te. but spontaneously, whilethe rema ind er of the pe rmanent dentition, i.e.

the successional teet h, exh ibits vc rv dclavcdor non -eru pt ion. Additiona lly , su pern u mer­ary teeth develop in the successional teet hareas in numbers tha t typically vary fromnone to around 12 in general, although thehighest reco rd ed number ever found wa s 63(Yamamo to et ,11, 1989). Apart from barrel­shaped teeth and the rare occurrence of peg­shaped tee th in the maxillary incisor a reaonly, the supernumerary teeth take the formof premolars in the premolar area, canines illthe canine area a nd incisors in the incisorarea. They may therefore be more ap propri ­ately referred to as supp lemental tooth .

Cleid ocra nia l dysplasia has an inhe ri tancepattern that is au tosomal dominant (Zeg arelltet al , 1978), with a high incid ence of newm ut ations at arou nd 20-40% of all cases(Shafer PI al , 1983). Several of the cases thatha ve been under our care come from familieswhere a pa ren t was affected, and thu s d iag­nosis was usually (but not alwa ys) mad e atbirth . For mo st of the ot he r c.1St.'S, a ten tativeor init ial d iagnosis was suspected onlyseveral years la ter, by the child's pocdiatri­cian or orthopaedist. although the d iscoverywas sometimes mad e at a dental examtna­tion. Corroborative evidence from a clin ical

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH2OO ~=~=~=======C'_

examination and a wider radiological exami­nation was then ob tained to es tablish thedefin itive di agnosis .

During the physical examina tion, the clini­cian should set ou t to confirm as many of thefeatu res described abo ve as poss ible. ' In par·ticula r, the pa tient sho uld be asked to approx­imate the shoulders, to confirm the clavi cleanomaly (Fig. 9.1). Palpa tion should also bemade of the area between the pari etal boneson the crown of the skull and between thefrontal bOIlI.'S ,11 the up per forehead/hairline

region. In both of these midline areas, asmooth and wide hollow, concavity or fu rro w(Fig. 9.2) may be clearly felt, in contrast to theconvex contour o f the sku ll of " nor mal ch ild .Rad iologica l examina tion should includeviews of the clavicles (Fig. 9.3), the fontanellesw hich may be seen on (Figs. 9.4, 9.5), latera land postero-a nterior cephalometric films (Fig.9.5), and an initia l panoramic film of the jaw s(Fig. 9.6).

The sig ns and sy mptoms of the cond itionarc very d istinct, but entirely benign. The y

Figu re 9.1

(a. bl The appro ximated shou lders of a cleidocr an ial dys plasia pa nent .

Figu re 9.2

Fron tal midline furrow p.lssin~ through the hair lin e.

Figu re 9.3

Ches t rildi llgr,1ph til show inct,mpll,tl' clavicles.

CLEIDOCRANIAL DYSPLASIA

Figll res 9.4 IlefU and 9.5 (righ t)

The p..." tern-anl~·rior (Idl ) and 1~Icra l (right) ccphalograms show abnormal crania l fonn. open fontanelles and numer­ous worrn ian bones (arrowed).

(a) (b)

Figure 9.6

(a) A I-t-year-old female cleidocrania l dysplasia pa tien t wi th a fu ll deciduous d entition an d two additional m,jxill,jryd eciduou s incisors. Only one ~'rupkd (deeply carious) pl'r Illilnenl molar is pr~":".·nl . Th...rc a rc 23 unerupted sUJX'rnu­merary te...th. in addi tion 10 l h~' 32 un eru pted pl'rm<ln~'n l te...th, Lt'. a tOla l of n I~...th! (b) A 13-y~',u-old male cleidocra ­ma l d ysplas ia pa tien t wit h rnony erupted pe rmanent te...lh an d only ont' ,,;upl'rn umeT.uy tooth.

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH202- - - - - - - - - - - - - - - - "-------- - - -ar c in no way debili tating or progress ive, th epatient is not physically or mentally handi­capped and other body systems are notadversely affected . Treatmen t of the overallmedical con d ition is therefore not advised(Shafer et .11, 1983; Tachdjian, 1990), and itsd iag nosis does little more than label the ch ildasan oddity,

The dental aspects o f the condition paint awry different pic ture of the se riousness of theramifica tions of cleidocranial dysp lasia, sincethey affect the face a nd oral structu res . Fromstudent to experienced practitioner in thedenial profession , an d out o f all p roportion tothe rarity of the condition , its clinical featu resare surpris ingly well known, again reflect ingits curiosity value rat her than any abili ty onthe pa rt of the profession to promote changeand correction. For ma ny deca des, the profes­sion has stood in awe at the enorrnirv of thedental problems tha t th ese cases p resent,unable to offer sa tisfac tory answe rs.

The denta l characteris tics include over­retention of the deciduous dentiti on, non­eruption of the permanen t dentition and thep r('S('nce of many supernumerary tee th.Nevertheless, there is no dental d iscomfort ordisturbance. unless the decid uous tee thbecome dec ayed . These tee th arc sma ll rela­tive to the growing face, and arc not visiblebelow the upper lip, pa rticula rly when anoften-seen an terior o pen bite is present.The vertical growth of the alveolar pro­ccsscs is genernlly deficien t. w hich leaves thepa tien t w ith a very shallow lab ial and lingualsulcus in both j.1W S. Taken together, thesefeat ures give the patien t an ed entulousap pcaf<1 nce, which may often be th e presen t­ing symptom.

Given that

(a) the child with cleidocranial d ysplasia haslittle by way of a ta ngible complain t (nopain, no swelling, no d ifficulty in fun c­tioning), ye t

(b ) the dentis t has d iag nosed a benign con d i­tion of ex traordi nary therapeu tic magni­tude,

(c) the dentist 11<15 no ava ilable gu idel ines onhow to even begi n to approach the reso­lution of the enormity of the p roblem,

(d) trea tmen t resu lts are im possib le to pre­d ict for someone who has never beforeseen such a case, and

(e) the degree o f facial deformity is usua llyof insufficient consequence to demandsurg ical mod ifica tion,

it is entirely understanda ble that a respons i­ble clinician will hesitate before undertakingtreatment.

The alternati ves arc

(a) not to offer treatment at all ,(b) to suggest the more rad ical approach of

ext raction of many teeth. followed byprosthetic replacement, or

(c) to advise an orthodontic-surgical treat­ment procedure, with an unknown levelof confidence in its result.

However, non-treatment becomes less of anoption as the patient grows older. Because ofconsiderable occlusal attri tion and caries,there is .1 progressive morbidi ty of the decid ­uous den titio n, which sta r ts in the early teen sand ga thers momentum over just a few years.Root canal treatment is often need ed , andres toration becomes di fficu lt. The patient'sappea rance suffers still further. with ared uced lower face height (Smylski et al .1974), impaired masticatory func tion, andcon tinuing facial growth contributing to theincreasing cverclosed appearance. Treatmentis needed to provide a n efficient masticatoryappara tus, and improvement s in the den talappear ance and the facia l proportions.

TREATMENT MODALITI ES

These goals may be realized in several wa ys.The recommended meth ods that have beenproposed o ver the period of many ye,l rs havem ost ofte n reflected the particu lar area ofdentistry in whic h the treating de ntis t hasspecialized. Therefore, to a degree. the modeof treatment may depend upon whose doorthe pa tien t first knocks!

CLEIDOCR ANIAL DYSPLASIA

Removable prostheses

The most popular approach ha s been to p ro­vid e the patien t with removable partia l or fullprostheses , which fulfils all the immediateneeds of the pat ient. Th is approach has beensugges ted by many only af te r the removal ofall the d eciduous tee th and the uneru ptedsupe rn umerary and permanent teeth (Wintherand Khan, 1972; Kellv and Nakamoto, 1974;Yam ..rmoto c t al , 1989f Given that the alveo larbone height in these cases is very limited,with shallow sulci, the dentist should ponderthe construction of replacement tissue-bornepros theses 10 years la ter. after ad di tional andia troge nic ridge resorption has occurred . Theabsen ce of alveola r bon e and th e thi nness ofthe mandible itself w ill ru le ou t the use ofimplan ts.

Others have ad vised retaining the standingteeth an d the constru ction of p ros thesesaround them (Fro mmer and Lal'eyrolerie,1964; Hilch in and Fairley, 1974; Kelly andNakamoto, 1974; Stewar t and Pres cott, 1976).A fu rther refinemen t recommen d s th eexploita tion of any standing tee th. togethe rwith the su rgical exposure of uneruptedtee th , to se rve as su pports for an overdentu re(Hitchin and Fairley. 1974; Weintraub andYasilove, 1978; Probs ter et al, 1991). By mak­ing it tooth-born e, the denture is less likely tocause fur the r rid ge resorption, but the sup-­porting tee th will d eteriora te quickly underthese circumstances, both from caries o f thecrown and the root surfaces and from loss ofpe riod on tal a ttachment.

Surgical relocation

In the search for a non-prosthetic method tha tutilizes the existing teeth, su rgical removal ofthe supern u merary teeth, follo wed by carefuldissection of the une ru pted tee th a nd thei rrepositioning or transplanta tion in to artifi­cially prepa red sockets , has been p roposed(M uller, 1967; Oksala and Fagerstrom, 1971;Shafer e t al , 1983). However, these stud ies donot appear to have been reported o n follow­ing long-term observa tion, and one is left to

presume that the tr ans posed teeth will , intime, und ergo fairly rapid pathologic rootresorption, as seen with other transplant edtee th.

These methods all suffer one serious draw­back, namely tha t the results thus achieveddeterio rate in time and thei r p rognosis is re la­tively poo r. When one considers that treat­ment for the condi tion is requ ired in thepatient' s sec ond or thi rd d ecade of life, thesemodalities must be cons idered to be of lim i­ted value a nd essentia lly inad equa te to thetask.

Orthodontics and surgery

Before the mid -1960s, while some limited pos­itive results we re obtained with orthodontics,the id ea W ,1 5 consid ered to be impract ical andfanciful, and was widely d erided . Ne verthe­less, it caught the imagination of several clini­cians, and , particul arly in the late 197Q:.; andearly 1980s, several publica tions appearedadvocating a surgical and ort hodonticmethod . The meth od used to bring about theeruption of the tee th was to extract the dccid­uous teeth . su rgically remove the u neruptedsupemumer.1ry tee th and expose the buriedpe rmanent tee th, w ith or w ithout the use of asu rgica l pack. depend ing o n the depth ofthe ind ivid ual tee th within the ti ssues(Elomaa and Elornaa, 1967; Smylski et al.1974; Hall and Hvland, 1978; Frnrnc a ndEvans, 1989). •

The pa tient wa s then seen in routine fol­low-up visits. until the teeth erupted or ha dreached a su fficiently accessible po sition.occlusa l to tilt' he eled gingival tissues, for th eapplication of orthod on tic band s or bon d edattachments. In other words. assisted t.' rup4tion was only p rov ided for those teeth thathad already par tia lly eru p ted. For these cases,char..actenzcd as they arc by a lessened p<)\,,'erof eru pt io n, ma ny mon ths will pa ss befo reteeth ap pear, and so me of the more deeplysited tee th may never erupt . Ad d itional su rgi­cal exposure is needed for some of these, butstill with no guarantee of success.

Immed ia te bond ing and ligation at the time

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH204- - - - - - - - --------------of surgery for th ese cases was introd uced inthe litera tu re in the 19805, when Tr imble et al(1982) and Davies et al (1987) each she wed asingle case in which th is was done. Theadvantage of being able to apply forces to themost intractably im pacted teeth is well illus­tra ted in these two cast'S.

The results and p rognosis that ma y beach ieved by a method involving su rgicalremoval of the unwanted decid uous andsu pe rn u merary teeth, followed by the ortho­d onticall y assisted eruption and a lignment ofthe natu ral pe rmanen t tee th, must be viewedas warra nting exploitat ion. Wha t, after all,cou ld be better than to res tore the de nt itionwith the pa tien t' s own teeth a nd with no rma lalveo lar bone su ppor t, through the med iu mof a healthy pe rtodoutal Hgement?

Since the orthod ont ic literatu re records fewatte m pts to s tandard ize orthodon tic trea t­ment stra tegy, be yond the above-mentionedsingle case reports, it mus t be conclud ed. thatthe orthod ontic option is not exercised formany cases and that there sccrn to be few cen­tres aro und the world where a significantgrou p of patients of any size has been treated .For these reaso ns, the present sta te of opinionregard ing recommend ed or approp ria te p ro­ced ure is diffi cult to asses s nccu ratelv.

Nevertheless, within this mod ality, threed ifferen t courses of action ha ve been sug­ges ted o ver the past few years, each based onthe experience of the trea tment of severalcases an d each with its own rela tive merits .These will be referred to as :

• the Toronto-Melbou rn e ap proach;• the Belfast-Hamburg approach:• the Jerusalem ap proach .

degree o f root development of the pe rmanenttee th d ictat ing the timing of each s tage.

Thus, initially, the d eciduous incisor teethare extracted a t 6 yea rs of age, followed bythe deciduous canines an d molars at 9-10years. Supernumerary teeth overlying thecrypts of the u neru pted pe rm ane nt teeth areremoved together wi th 'subs tantial amou ntsof bo ne to uncover the crowns (of the pe rma*nent teeth) to their maximum d iameter' . Thetee th a rc left wid ely exp osed . The Melbourn eteam prefers to expose the incisors a t a sepa­re te an d add itional su rgical episode, an d thisis don e after the first m olar bands are placed ,followi ng th e late eruption of these teeth,which may reach full expression only at aboutthe age of 10- 11 years. Su rgical packs areused to maintain the patency of th e surgicalexposur e and to safeguard access for eventualbo nd ing of the teeth.

The expecta tion is that , following theremoval of the obstructive elements , i.e. thedecid uo us and su pe rn u mera ry teeth, togetherwith a liberal amount of bone and so ft tissu e,the teeth will then eru pt 'und er their ownsteam' to a varying d egree an d ove r anextended time frame. When convenient,orthodontic brackets are bonded to ind ividualtee th, a nd these are d raw n to a light archw ire,which spa ns the unsupported premolar /ca nine areas, from the ba nded molars to oneor mo re anteriorly erupted incisors . Teeth arethen d rawn to the arch wire, depen d ing onthei r becoming accessible to bracket bond ing.

Smy lski et al (1974) and Hall and Hyland(1978) d o no t propose any specia l o r purpose­d esigned appliances to deal w ith the ver ticaltraction that is need ed in every Mea of themouth, bu t ap pear to rely on the employ mentof conven tional method s used in routineorthod on tic treatment.

THETORONTO-MELBOURNEAPPROACH

This method was origbw ted by a team fromToronto tSrnvlski et al. 1974) an d was laterfurther developed in Melbourne (Hall andHyland , 1978). Surgical p rocedures are per­formed in a stage-by-stage series, underendotrachea l general anaesthesia, with the

Limitations

In this method, the pa tien t is under treatmentfor man y years, beginning at a very ea rly ageand requiring several recommended andfairl y extens ive surgical in terve nt ions, f01 -

CLEIDOCRANIAL DYSPLASIA

lowed bv several smaller ones for ind ividualtee th. The age of the pa tient in the ea rlystages a nd the 5COPC of the su rgery are themajor deter minants as to wh ether these needto be ca rried ou t under genera l anaestheti c.

The decid uous anter ior te..-eth ar e removedat an early stage, in order to encourage theeruptio n of perma nent inciso rs. Nevertheless,in their subseq uent reco mmenda tion to fu llyexpose the permanent incisor teeth in a di s­tinct and separate surgical s tage. Smylski et al(974) and I iall and Hyland (978) recognizethat spo ntaneous eru ption does not alwaysoccur. This mea ns that the patient is anteri­orly ed en tul ou s for some considerable time.Th is would seem a high price to pay for whatma y be undue optimis m rega rding the po ten­tial in cleidocranial d ysplasia for norm alerupti on. In two of the three cases describedin Smy lski ct al (974), unerupted supernu­merary teeth were not prese nt in the anteriorseg ments, and the pe rmanen t inciso r tee thresponded to simple exposure and pa cking.However, there arc ma ny caSC5 w here sponta­ncous eruption docs not occur, this being oneof the d iagnostic crite ria of the cond ition,w hich may be associated specifically with thefrequent presence of supernumerary tee th inthis region .

The placement of attachments to the dee plysited perma nen t teeth is not performed at thelime of surgery, but only so me time later ,after fu ll healing (by secondary intent ion) hasoccurred and the su rg ical pack s have beenremoved . Thu s, at each su rgical stage, valu­able time is lost between the exposure an d theforce application needed to encourage theeruption of the teeth .

THE BELFAST-HAMBURG APPROACH

Simul taneo usly, bu t qui te independen tly.Richardson and Swinson (1987) of Belfast andBchlfelt (1987) o f Ham burg proposed. a d ia­metr ically opposite method of treatmen t ofcleidocranial d ysplasia . They recognized that,w hile there is the need for ex tensive surgeryin these cases, th is could a ll be com pleted atone time, includ ing the extract ion of all decid-

uous and supernumerar y teeth and the expo­sure of all uneru pted pe rmanent teet h . This iscarried ou t un der general anaesthesia, und eropcrntmg theatre cond itions and with surgi­cal packs p laced over the remaining teeth toencourage epithelializa tion of the exposed tis­sue, which is the essence of healing by sec­ondary inten tion.

Du ring the succeed ing weeks, these sur­gical packs rema in in p lace and perhapschanged over a further shortish period , un tilbrackets may be co nveniently bond ed to theexposed teeth-This ca n then be done underwhat the proponents consider to be mo rereliable cond itions for bonding than thosepresent during the surgical proced ure.

Whether or not eruption of these teethoccurs witho ut assistance is the subject ofso me debate, with one source insisting that,while there is apparent improvement, this isdue to the radi cal lov, of surround ing softand hard tissu e during the surgical proce­dure, ra ther than actual vertical den tal change(Miller et al, 1978). Nevertheless. even withthe most favourable and optimistic assess­ment, there can be no doubt that the erup tion\..-ill be neithe r suf ficien t no r reliab le enoug hto eliminate the need for extrusive mechanics.As w ith the Toron to-Melbourne approach,appliances con sist of molar bands andbonded brackets, with long Sp.l0S of unsu p­ported and relati vely fine nrr hwi re used tovertically develop the pa rtiall y erupted teeth.

Limitations

By recommend ing all extrncttons and expo­sures at one time, the Belfast- Hamburg surgi­cal policy has clear adva ntages from thepatient's point o f view, although a balancehas to be stru ck in terms of timing this prnce~

dure. The earlier-developing permanen t teeth(particu larly the inciso rs) should not beexposed too late in their develo pment to lost',my erup tive po tential tha t they may hove,while the later-develo pin g teeth should notbe exposed too ea rly while thei r roo ts areinsufficien tly developed . Accord ing ly, theBelfast team (Richardson and Swinson , 1987)

THE ORTHODONTICTREATMENT OF IMPACTED TEETH206---- - - - - - ---------- ---reco mmends tha t the one- time, comprehen­sive, su rg ical interven tion be performed atage 12-14 years.

The immed iate ad van tage of this po licy is\'Cry clea r and encourag ing. although itsdrawba cks Me of conside rable consequence.101.1 not so obviou s. By d elaying treatmen tuntil this I.He age, the teet h of the normalseries will have bee n held d eep down in basa lbone by the supernumerary tee th, partiru­larlv in the latera l incisor/ can ine/premolararea, for an extended period of time . Theirroo ts will have reached an ad vanced stage ofdevelop me n t in these cram ped circumstances,which is likely to exaggerate the existing ten­dcncv for ,1 st u nted. tortuous and d istortedroot morpho logy (becker and Shochat, 1982).Remova l of the unwanted ext ra tee th at thislate stage will relieve the impac tion of thepe rmanent teeth of the normal series, but itwill do ~l at ,1 time when thev exhibit evenless potentia l for sponta neo us 'eru p tion, pa r­ticularly in the incisor region, since the roo tapio...-s will already have been com pleted.

During growth in a normal child and withthe eruption of permanent tee th, the vert icaldevelopment of the alveola r processes thatoccurs makes .1 s igni fican t con tribu tion to theheig ht of 11ll' lower face. It also leads to thees tablishment of deep ves tibular and lingualsulci, with a clear d ifferentiation of widezones of oral m ucosa and a ttached g ingiva . Inthe un treated cleid ocranial d ysplasia patient,vertica l grow th of the alveol ar bone appearsto be mar ked ly d iminished . Th is brings aboutthe typ ically red uced height of the lowerth ird of the face that is so freque ntly a featureof the cond ition. Thu s, with the late remova lo f the un wan ted deciduous and supernumer­ar y teet h at ,1 time when most of the patient' sgrowth has already occurr ed, the ultima tever tical al veola r growth that accompanies theerupti ng pe rmanen t teeth will be cor res pond­ingly less, leaving a shallower sulcus, anabsence or red uced w id th of attached gingivaand an inco mpletely vertically devel opedlower th ird of the face. in the final an alysis.

Furthermore, and in add ition to removingthe un wa nted supernumera ry teeth, it is nee­ess.uy h i g,lin access to the cani ne and premo­lar teeth of the no rmal series and to expose

them widely. When the proced ure is per­formed at this late stage, these target teeth arevery deeply si tua ted, often with their devel­oping root apices close to the lower border ofthe mand ible. This necess itates the removalof conside rable quant ities o f bo ne (Smylski etal, 1974) and , as reco mmended by severalau thors, the placement of a surgical pack overand aroun d the crowns and necks of the teethto prevent bony healing-over and to encour­age spontaneous eruption. This packing pro­cedure w ill ma rkedly delay healing, and isdesigned to prevent the reparat ive filling-inof bone. It is d ifficult under these circum­stances to avoi d pushing the pack into thearea of the eEJ, which will inevi tably lead toa poo r periodonta l prognos is for the finallyerupted tooth, with an exposed eEj and less­ened bone support IKohav i ct at 1984).

The frequ ent need to change packs over along period incurs pain, d iscomfort and nu i­sance, d ifficu lty in maintainin g oral hyg iene,and a lim itation of normal function, with along-term bad tast e and od our in the mou thdue to the unhygien ic circumstances. Fromthe surgeon's point of view, thi s entails see ingthe pa tient for many time-consu ming ap­pointments. There is no active encouragementof eruption un til bra ckets may be success fullybon ded and traction applied. in a case alread yafflicted by slow or nun-eruption as a charac­teris tic of the disease. Thu s, at an age whenfacial appei'ITalKC is very important , thepa tient will spend an una ccep tably long timew ithout tee th. Fur ther more, bon e regen era­tion will have been slowed down by the useof a method involving healing by secondaryintention (Howe, 1971). Eru pt ion is thusde layed and a growing over of the soft tis­sues, to re-cover the deeper and newlyexposed teeth, mily still occur.

It becomes clear that su rg ical policy is gov­erned by the w illingness of the operators toplace at tachmen ts at the time of surgery.Witho ut them, access to the unerupted teethmust be guaran teed by the surgeo n perform­ing wide opening and rad ical bone resection,with the placement of surgical pecks. Withthem, a conservative surgical policy is poss i­ble - on ly enou gh bo ne is removed to allowaccess for till' placement of a smal l eyelet

r

CLEIDOC RANIAL DYSPLASIA

attachment on the minimall y exposed too thsurfa ce. The surge ry may then be a imed atpn..-scrving ra ther than removing bone, sincethe presence of bo ne docs not seem to hind ermechanically encouraged eruption of thetee th in these cases. Its lac k wou ld be agreater dravvback in terms of the even tualdegree of bo ne support and th us of the peri­odont al prog nos is o f the eru pted teeth(Ka h ilvi ('I a l, 19$-1).

It has been reported (Srnyls ki et al, 197-1-)that denser alveolar bo ne is pres en t in clei­docranial dysplas ia. We have not foundabnormal bone in any of the cases in our care,although the observer could understandablybe misled bv the fact tha t cortica l bone isfound, to the relative exclusion of spongio­su m. It should be remembered that theimpaction of many tee th within the ~lWS takesu p much of the volume within the body ofthe mand ible whe re spongiosum wo uld nor­mally be p rese n t. Thus, while cortical boneencompasses all these teeth an d is p resent innorm al amou nts, sponglos u m is sparse.

THE JERUSALEM APPROAC H

This method Wecker ct al. 1997a,b) was pre­sented for the firs t time at the sa me forum asthe Belfast-Hamburg ap proach, d escribedabove (Becker an d Shteye r, 1987). Its mod usope randi is quite d ifferent from either ofthe two earlier approaches. The Jerusalemapproach is based on a rationale tha t isrela ted to the abnormal d ental de velo pmen tof the patient and on the factors that produceit.

Th is cornprchcnsive approach to treatmen tad dresses the following po ints:

(a) a recogni tion of the clinical features of thefacial, oral and dento-alveo lar s tructuresin the d isease;

(b) the surgical measures that are required toprovide access to the areas concern ed;

(c) the need for a n or thod ontic stra tegy toenable the applica tion of extrusi ve mech ­an ics to the buri e-ci teeth in an efficienta nd reliab le ma nner:

(d) attending to the pat ien t's psych ologicalwell-being by focu sing the earliest s tagesof trea tment to the resolution of theincisor impactions.

Clinical features

Cleid ocranial dysplasia pa tients ex hibit eachof the following fea tu res to a variable degree:

(a) non-resorption of deciduou s tee th roots;(b) presence of su pe rn u merary tee th. ma rk-

edly d isplacing the d eve loping pt.. rma­ncnt teeth and providing a physicalbarrier to their eruption;

(c) lessened eruptive force, although erup­tive movements arc evid ent;

(d ) poor vertical d evel opment of alveolarbone , as w itnessed by a shallow sulcus, ,1

red uced height o f the lower Ieee an d aClass III skeleta l tendency, due to anund erdeveloped maxilla and to a coun­terclockwise ma nd ibula r rota tio n;

(e) late bu t normal and un hind ered eru ptionof first and , so metimes, second perma­nent molars in bot h arches :

(0 . la te d enta l devel opm ent, as jud ged by theroo t d evelop ment of the perma nent tee th,whether erupted or u nerup ted - a 12­year-old patien t will typically show ad ental ag e m ore a pprop ria te to that of a 9year old (Hall and Hyland, 1975; Beckeret al , 1997b; Scow and Hertzberg. 1995).

Surg ical therap eutic measures

The timing regard ing the actual exposu re ofthe perm anen t teeth is critical, and only twoin terventions are plan ned a t d is tinct po ints intime, depending u pon the exten t of roo td evelop ment, as follows.

Inte rve ntion 1

At the dental ag e of 7-8 years, the anteriordeciduous tee th, together with all the supe r·nu mcrary teeth, in both the anterior an d

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH2D8 ~====:..::::===_===_=::_:

posterior ar eas, arc ext ract ed . The anteriorpe rmanent teeth, w hose roots arc su fficientlydeveloped (two-thirds th eir expected len gth)art' su rgically exposed. a ttachmen ts areplaced immediately and flaps fully d osed .Given the usua l lat enes s in development ofthe denti tion in these cases, the chrono logicalage o f the pa tient at this stage is usuallyaround 10-12 years. At this time, the poste­rior pe rmanent tee th a rc ,11 an early sta ge ofdevelop ment, with their root s less than halftheir expec ted fina l length. The su rgica l inter­vcnt ion in the p rem olar/ cani ne region istherefore lim ited to remov al of su pern u mer­ary teeth . Actual exposu re of the develop­mentally immature posterior teeth of theper ma nen t series is not und ert ak en, and theirden ta l follicles are left in tact until a la ter time.

closure (Bec ker and Zi lbcrman, 1978; Beckeret .11, 1983; Koh avi et at 1984; Vermette ct al ,1995).

Immed iately following the first int erven­tion, it becomes necessary to supplement theeruptive force of the incisors. In this way, thevertical migration of the teeth tha t rapid lyocc u rs brings with it a p ronounced verticald evelopmen t of the alveola r bone (Smylskt et.11, 1974). Thi s is all planned when mot d evel­op ment is between half and thn..ee-quartcrs,which corresponds to the stage o f develop­ment at which teeth norm ally eru pt (Cron,1962), Simi larly, occlusally directed forces areapplied to the p osterior teeth immediatelyfollowing the secon d intervention.

Intervention 2

The d ental age of 10- 11 ye.us (chron ologicalag e 13+ years) is the most app ropria te timefor the second intervention , because the roo td evelopment o f th e poster ior successionalteeth will be sufflclentlv we ll advanced. anderuption and alignment of the incisor teethwill have been achieved. Thi s interventionInvolves the exposu re of the teeth in thecan ine /premolar reg ions and the im mediateplacement of orthod ontic a ttac hments. Thespecial req u irements of the su rgical proc e­dure rela te to the conservati on of bone in gcn­cml and of the co rtical port of the bone inpa rticula r. Remova l o f the unerup ted super­numera ry teeth with a minimu m o f buccalpla te of bone crea tes enough space aroundthe crowns of the impa cted pe rma nent tee thof the normal ser ies to allo w the im mediatebon d ing of attachments. The ling ual plate isleft in tact and at its orig inal heigh t. Max illarysecon d p remolars milY req uire a pala ta lapproach, in \...hich case the buccal p late isleft intact.

Libe ral soft tissue exposu re of the surgicalfield is advised, to enable good vision andaccess and to help in maintaining the conserv­atwc attitude to the removal of bone. Themuco-periosteal flaps are finally replacedinta ct an d sutured bac k, withou t the use ofpacks, in the manne r of p rimary soft-tis sue

Orthodontic requirements

In the broad overview, the prov ision o f spacewithin th e arch is made by appliance­ge nerated an tero-posterior expansion of pos­tenor-versus-a nte rior erupted teeth (Elomaaand Elornaa . 1967), while th e removal ofdeciduous and supernumerary teet h providesspace in the ve rtical plane. In this way. andw hile space is bei ng pro vided, self-realizationof any eruptive po tential that the pe rm anentteeth may possess is pe rmitted , to present theopportu nity fo r them to migrat e towa rds theocclus al pla ne an d to take u p a more norm aldevelopmenta l position wi thin the alveolus.This seems to occur to a varying d egree, toallow the roots to develop in un cramped cir­cu mstances and thereby lead to the acqu isi­tion o f a more normal root mo rp ho logy(Becker an d Shochar, 1982). Ho wev er, it isimportan t to em p hasize that no reliance isplaced on spontaneous eruption of these tee th(Smylski e t al, 1974) althou gh. sho uld th isoccu r, it is on ly to be welcomed an d will sim­plify the trea tmen t p lan . However, theJeru salem approach has been form ula ted tocombat the wors t eventuali ty, i.e. non­eru p tion.

From the point of view of the orthodonticmechanothera py, achieving efficient forceapplication in an approp ria te di rection for

•

CLEIDOCRA NIAL DYSPLASIA

each tooth requires examination of the follow­Ing poin ts.

(a) There mu st be a sufficient number oferupted an cho r teeth in the mou th to actas a base fro m wh ich forces may begenerated . As we have already pointedou t, the pe rmane nt molars usually eru p twithout help, end one or two incisorsmay also be visible.

(b) One has to design a rigid appliance framethat will endure chewing and ot her func­tional and parafu nctional movementsthat may be ex pected to occur duringeveryday o ral fu nction. considering thelong spans of free. unattached and unpro­tected archwire, mesial to the few eruptedanchor molar teeth.

(c) Ind ivid ual and groups of u neru pted tee thmust be subjected to ligh t continuousforces.

(d ) Appliance d es ign has to feature su fficien tversatili ty to enable it(1 ) to app ly ve rtical extru sive forces to

eru pt the impa cted tee th rap id ly;(2) to open spaces between recently

eru pted tee th, to p rov ide room forother unerup ted tee th and to es tab­lish interpro ximal co ntacts and archform;

(3) to bri ng these tee th into occlu sionand to u p righ t their rootsand all th is with only m inor alter ­

ations!

The patient's psychological well-being

In Cha p ter 5, we poin ted out that it is inad­missible to leave even the youngest patientwithou t fron t teeth for an extend ed pe riod oftim e, and that it is im portant to make thechild aware that effor ts arc bei ng mad e to rec­tify suc h a situa tion speedily . The physicalobst acles to erup tion (i.c. the d ecid uous andsu pernu mera ry teeth) must be removed, inorde r to faci li ta te the eruptio n of the anter iorteeth. Proper tim ing is crit ica l. This shouldonly be done at the age when the permanen tincisor tee th indica te adequa te roo t d evelop-

rnent for eru pti on and only when an appli­ance is in p lace, to actively sup p lement theirlimited eruption .

DENTAL CROWDING

Whe n st udying the radiographs of anu ntreated cleidocran ial dysplas ia patie nt, oneis im mediately stru ck by the Intra-bonycrowding p rovid ed by the large nu mber ofunerupted pe rmane nt tee th (those of the nor­mal se ries and the su per num erar ies). Duringsurgery and after all o f the superfluous d ecid­uous and su pe rnu merary teeth have beenremoved, the surgeon and the orthodontistwill view the open su rgical field , and . giventhe rel ati vely un der-d eveloped alveolar p ro­cesses, will find it d ifficu lt to sec how it ispossible to fit all the remain ing permanenttee th in to the d ental arch a nd in fu ll align­ment.

On the basis of th is 's po t' d iagnos is, theorthodont ist will be tempted to advise theoral surgeon to take advan tage of the p revail­ing general anaest hetic to remove a p remolartooth in each quadrant of the mouth, in whatwould appear to be a log ical step necessa ry tored uce the apparent crowding. However, formost cases, this step wou ld be regre tted la terwhen the subseq uent s ize and form of thealveo lar proc ..-sscs, which may be developedas a by-produ ct of the mechanical eruption ofthe tee th, become ev id en t.

Initially, th e ap plia nce-generated eru p tionof the anteri or teeth b rings the teeth int o themouth, with a p ronounced lingua l tipp ing oftheir long axes. Th is is due to the influence ofpurely vertica l forces that will have beenbrough t to bear on th e permanent incisors,whose d evelopmental position is very muchlin gua lly p laced and apical to the recentlyextracted d eciduous incisors .

For this reason, th e pe rmane nt incisorsmust be tipped labi ally, to crea te a no rmalarch form and to provide a more procumbentsu pport for the lip s. This will contributemuch ad d itional space in the denta l arches forthe prem olar and canine teeth, and will beinstru mental in s ignificantly elimina ting the

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH210------- - - - "-'------'--'-----'-----'-------denta l crowd ing and the pa tien t's edentulousap pearance. It is only after comple te oralmost comp lete eruption has occurred that adecision should be mad e as to whetherextractions ar e needed . Our limited experi­ence h..as shown tha i, in thes e youngerpa tients. extractions are not needed in thefinal analysis and that adequa te space foralignment o f ,111 the teeth anterior to the firstmolars ma y easily be provided .

RETENTION OF THE TREATED RESULT

Once the permanent teeth have all reachedtheir fina l posi tions in the arch, the removalof the fixed appliances will not usu ally beaccompanied by a loss of ve rtica l height ofthese teeth, desp ite the fact that their ver ticalpositions will have changed. so d rasticallyover the treatment period . Th e lateral widthof the two arches will have been se t initia llyby the first permanent mola rs an d the over­retained d ec id uous teeth. The usc of fixed lin­gual arches d u ring treatmen t will haveallowed goo d co ntrol aga ins t any change inthis d imension. Therefore the orthod on tistmay con fidently expect no natural post­treatment alterati on of the a rch width.

The on ly d ilemmas of any conseque nce inthe co ntext of retention relate to the labio­lingual post-treatment posit ion of the incisorsof both jaws an d to those teeth that haveu ndergon e rota tion al orthodontic movementduring treatment.

It is axiomatic to say that proper lab io­lingual po sitioning o f the anterior teeth in anypa tient is depe nde nt on the muscular balancebetween th e lips an d the tongue. Teeth placedtoo far labially or lingually will inev itably bepush ed by the lips o r tong ue in the oppositedirection, when all retaining d evi ces arcremo ved . Du ring the o rthod ontic treatmentof the nor ma l patient and in the interests ofstab ility, the position s of ad jacent teeth areoften used as a yardstick to which the d is­placed teeth sho uld be mo ved to achieve thedesired alignment. Alternatively, cephalomet­ric sta nda rds m.1Y be p referred aga inst whichto compa re the d ent ition, such as the lower

incisal edges vis-a-vis the A-Po line (Ricketts,1981).

With the cleidocranial dysplasia pa tie nt,there is no scientific way to judge the 'biologi­cally correct' and therefore s table position ofthe incisors. No r are there an y pu blishedcephalometric d ata on a large gro up oftreated an d post-re ten tion cleidocrania l d ys­p lasia pa tients, to help es tablish such 'norms'.By no means may the cephalometric va lues ofthese patients be co mpared with the averageval ues found in the various growth s tud iesthat have bee n carried out wit h samples ofno rmal pa tients. Consequently , the use ofHold away or Ricketts analysis an d a growthp red iction analysis, as p roposed elsewhere(Hall and Hyland , 1978). is complete ly invalidan d highly misleading. The orthodontist cannever be sure of the stability of th e final resultin this aspect of the trea tmen t, and some formof long- term retention will us ua lly be ad vis­able.

Th is be ing so, we ha ve adopted th e viewtha t the incisors should be brought well for­ward, extruded below the u ppe r lip, toslig h tly over-compe nsa te to some degree forthe years that the patient has lived with veryshor t and larg ely invisible teeth. When onlydeciduous tee th were p resent, or in the initialstages of treatment, the pa tien t's so cial inter­reaction with othe rs will have been d icta tedby a des ire to ma sk the missin g an te rior teeth,and he or sh e may have ad opted un natu raland unsmili ng facial expressions and a retir­ing attitude. Once the teeth align me nt hasbee n completed and ap pliances rem oved, aposi tive and dram atic ps ycholog ical changein patients' a ttitud e to life see ms to occur,an d, from then on, many seem to wa lkaround with a per manen t smi le on their faces,conscious ly an d delibe rately d isp lay ing theirnew-fou nd teet h!

After a short period of time with con ven­tion al removable ret ainers, ou r p ractice hasbeen to p reparl' and ap ply fixed m ulti­stra nded bon d ed retainers to the max illaryand mandibular six an ter ior teeth (Zachrisson,1977; Becker and Goultsch in, 19R4; Becker,1987). These will then hold the labio- lingue lpositions of all the a nterior teeth, as well asp reven ting rota tio nal relapse. The conven-

CLEIDOCRANIAL DYSPLASIA

tiona ! remo vable re taine rs m,1y then be dis­carded .

THE JERUSALEM APPROACH INCLI NICAL PRACTICE

Pa tien ts who are suspected to be sufferingfrom cleid ocranial dysplasia arc referred to usthrough d ifferent ag encies, includ ing the vari­ous medical speci alties an d general dentalp ractitioners or d ental specialists. A smallp ropor tion also arr ive on their own initia tive,requesti ng advice and help in the search for asolu tion to the presence of 'w ry small teeth'or to their 'toothless' appear<1 1l(l' .

ln order to firs t confirm that the pati entdocs indeed su ffer from cle idocranial dyspla­sia, ou r d iagn ostic rou tine has come to include

(<1) a clinical exa mina tion in sea rch of thegeneral characteris tics of the cond ition,w hich takes in the form of the craniu m,the face an d the clavicles, includ ing themob ility of the shou lders;

(b) an intra-oral examination to rela te theeru ption statu s of the d entition vis-a-visthe patient' s chr onologie age;

(c) a rad iographic evaluation, which p lays acritical role in the con firmat ion of the clin­ical diagnosis, includes a ches t X-ray andantero-po sterior and la teral sku ll rad io­g raphs, which arc pe rformed in acephalostat.

At the same time, a panoramic radi ograph isstu d ied and su pp lemented with periap icaland occlusa l views, as required .

Once the d iagnos is has been confirmed ,genetic counse lling is offered to the parentsregarding their own fut ur e o ffsp ring, butmore particularly rega rding offspring of thea ffected ch ild. An impo rtant par t of thegeneticist's exam ination will includ e gathe r­ing information about rela tives an d the poss i­bility tha t other, mo re d ist ant, familymembers may be simila rlv affected . Trea t­me nt of the cond ition will [m'olve the ta lentsof a team o f three dental specialists. wo rkingin close co llaboration, an d the firs t stage maybegin immediately.

Stage 1: Assuring the health of thedentition

Treatment of the cleid ocra nial d ysplasiapatient will necessita te the wearing of ortho­dontic applian ces for several yea rs. Thereforean essential requirement in all cases is that thehealth of the d entition be guaran teed byproper oral hygiene ins truc tion, with follow­up to check that an ad equate level of com pli­ance is attained . Appropriate use of fissu resealants a nd fluoride ap plications is recom­mended . Carious teeth w ill need to betreated , but , in order for the paed odon tist tobe in a position to decide on the type ofrestora tion indicated . the timing of the extrac­tion of the rema ining deciduou s teeth willneed to be d etermi ned at the ou tset.

Stage 2: Vertical co rrection in the incisorregion

For most cleidocranial d ysplasia cases, a t d en­tal age 7-8 yea rs, a ll firs t permanent molarswill have erupted . Sometimes, one or more ofthe permanent incisors will also have eru p­ted , but the following description o f the tech ­nique will assume the lea st fav oura ble ini tialscena rio.

Orthodontics

Plain orthodontic band s arc fitted on theeru pted first mola rs (Fig. 9.7), and a com­pound imp ression is taken of eac h d ent alarch. The bands ar e then carefully sea ted inthe imp ress ion s, and a model Is cas t. Hea vysold ered palatal and ling ual arches are pre­pared on the tw o models, and single solderedbu cca l tubes (0.036" round ) a re loca ted run­ning mesially, close tothe buccal s id e o f thedecid uo us tee th, parallel to th e occlusal p lane.A misp laced firs t pe rmane nt mo la r may needto be aligned with a remo vable app liancefirst, in order to be ab le to align the bu ccaltu bes accurately as d escribed, since the effi­cien t wo rking of the ap pliance d epends onthis.

THEORTHODONTIC TREATMENT OF IMPACTED TEETH212. ~::..::.~==_=__=~=_=__~==_=__

Figure 9.7

(a) Plain ba nds ha ve been ada pted til the maxillary left seco nd deciduousmolar an d the firs t pt'rm,lnt'nl molars in tbc other th ree <\u,IJ r,m t'i. (b) Anupper (shown he re) an d lower compound im pn.."sions ,UI' made. (el Thebands are removed from the mouth and carefully Tl.'P1,lCOO in the impres­sion. The bands iln" the n p.lrtially filkJ with wax, be fore a mod el is poured.Cd) The cast model with accurately tocat..-d and stabilized molar bands. Ie!The occlu sal view of the man d ibular model shows right ilnd It'll tubes con­verging in the mid line and the lingual ilrch in place. (f) The heavy 'incisor­erupting' archwire is slotted intu the molar tubes, "loll' theSeshapcd hoo k soldered in the canine area and the anteriorly soldered fioe­wi re frame. (g) Disassembled mandibular appliance ready for intra-ora lplacement. (h, i) The appliances cemented in the mouth.

,,)

(b) 'e)

'dl Ie)

•

CLEIDOCRANIAL DYSPLASIA

(Fig u re 9.7 COlll illll,'l1)

Ihl

A heavy 'inciso r-eru pting' archwirc is pre­pa red for each nrch in ad vance (Fig. 9.7f), an dits fun ction is to achieve a correction in thever tical plant'. This archwirc is made of0.036" rou nd wire, which slots into the buccalmolar tub es up to a predete rmined bayonetbend Oil ea ch side. Th is ho lds the wire 2- 3mm labial to the anterior teeth a nd 3-4 mmgingival to the occlusal plane. In the caninearea, ,10 Scshaped hoo k is soldered , wi th itsmcsi..'IUy pointing extremity on the occlusalside and the d istally pointing ex tremity gtngi­val. In the midline area, ,1 small fine wirefra me is also sold ered, and po ints towa rdsthe sulc us d ep th .

An ' inciso r-alig ning' arch wire is also pre­pa red in advance, although it will not be pu t

Igi

(i)

to usc u nt il all the pe rmane nt incisors ha vebeen full y eru p ted . This consists of 0.020"internal-di ameter tube sid e pieces, whichfree ly slide accu rately into the 0.036" buccaltubes, without allowing lateral 'p lay ' . Thetubes <Ire cu t so that thei r mesial ex tremity isin line w ith the di stal of the deciduous ca nine.A length of 0.0155" or 0.0175" multist randedwi re is then d ra wn into the bucca l s ide-piecetubes, an d is made to 'friction-fit ' by inco rpo­rati ng three or four sharp be nd s in that par tof the wire. This updated ve rs ion of Johnson'stwin-wi re arch (Johnson, 1934; She pa rd , 1961)is p laced to one side un til it is needed at thatlater stage, w hen it will be U5(.U to achievecorrection (If the alignment of the teeth in theho rizontal plane.

Surgery

The patient is now read y for the first surgicalinte rve ntion (Fig. 9.8), a t the completion ofwhich the patient will hav e lost all of theanterior d eciduou s teeth and w ill also havehad the un eru pted supem umerary teethremoved . Fine p igtail ligatur es will have beenpla ce-t in the eyelet a ttachments bonded tothe incisor teeth, and these w ill be the onlylink betwee n the invis ible unerupted perma­nent tee th and the exterior (Fig. 9.9). Decidu­ous tee th not associa ted with su pe rn u meraryteeth arc ge ne rally left u ntil the ne xt. su rg ical

,<I

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

stage. The sur gica l flaps are fu lly suturedback.

Orthodontics

Still under the endotracheal an aesthesia, inthe operating theatre, the p repared 'incisor­erupting' a rchwtre is p laced in the buccaltubes and secu red by dra wing a chain elast icmod ule be tween the d istal of the bu ccal tubesto the mesially pointing extremity of the5-hook. The archwire is raised with lig ht fin­ger pressure, an d engag ed by loo p ing the pig-

'bi

en

figure 9.8

A 1 .J.y~·.lr....,ld r.lti~'nt. (,1-<) Intr.1.....r.l[ views of initial condition. (Jl Ant~'rior in tra-ora l view of appliances in place.

CLEIDOCRANIAL DYSPLASIA

tail ligatures around it . Since these pigtails aretied d irectly to the bur ied incisor teeth, thisdisplacement of the archwtre elicits a verticalextruding force on the unerupted teeth (Fig.9.9c).

This force generates a rapid response of theteeth, as witnessed by elongation of the pig­tail liga tures, over a period of a few weeks. Bydisp lacing the archwire apically and then'rolling up' the pigtail around it, extrusivepressure may be reapp lied over several visits,until eruption occurs. To support the ortho­dontic anchorage, a large fine-gauge elasticshould be used to engage the distal pointinghooks on each side of the maxillary and

(,)

(c)

mand ibular archwircs. This 'box elastic' pro ­vides an intermaxillary vertical force to eacharchwire. If the midline portion of thestretched elastic is laid over the soldered ver­tical frame, tissue impingement may beavoided (Fig. 9.10).

Stage 3: Horizontal correction in theincisor region

Orthodontics

The incisors eru pt relatively quickly and witha strong lingu al inclination , in general. At that

(h)

f igur e 9.9

The same patient as in Fig. ':I,ll. (fl) Four maxillary incisorshave been exposed and attachm ents bonded. (bl Sixmand ibular anterior teeth haw been exposed and attach­ments bonded. The exposed chin bu tton and the lingualarch indicate the depth of these teeth. (c) The 'incisor­eru pting' archwirc is replaced when full-Hap suturing iscomple ted, and the steel ligature pigta il~ Me made toensna re the arc hwire, which h,lSbee n dis placed superiorlyby ligh t finger pressu re.

215

216

(il l

(0'

point, their eye lets should be replaced by theorthodontic bracket of the or thodontist'schoke, which should be sit ed in the routinemanner (Fig. 9.11). The prepared 'incisor­aligning' archwire is then tied or pinned intoplace, where its first task will be to undertakethe levelling phase of treatment, i.e. incisorheight , ro tati on an d , in the edgewise tech­niques, u prigh ting. With proper buccal tubeor ientation at the outset, the long buccal tubeside pieces ma in tain the achieved. verticalextrusion, while p roviding resistance to d is­tortion and stab ility. The light 'box' elas tics

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

(b'

Figu re 9.10

The !O<1 me pat ient as in Figs. 9.8 an d 9.9. (a) AI 5 weekspost-surgery, d wry light an terior 'boll elastic' is placedon the d ist ally poi nti ng element of the 5-hooks in thecanine areas to en hance the anchorage. Note the U~ ofthe mid line frames to prevent tissue impingement. Cb) Al<;I weeks post-surgery, five incisors have erupted , an d thearc hwinos have ","-en disengag,"CI to increa-e their deflec­tion. Cd Re-engaging the archwires illus trat es their rangeof effectiveness.

may be attached to the latera l incisor brac k­ets, to conti nue the vertical extrusive force, ifand wh en necessary .

As levelling proceeds, the mid d le portionof the 'in cisor-aligning' archwire may be sub ­stitu ted for heavier and thicker wires (Fig.9.12) until an 0.018/1 or 0.020" w ire is in place,using the sa me side pieces . At this poi nt , anexpand ed coil spring is placed on Ihe sidep ieces, which now have a 's top' placed ontheir mes ial end. When the side pieces arereplaced in the buccal tubes, the coil sp ring isco mpressed between the buccal tu be and the

CLEIDOCRANIAL DYSPLASIA

'd

mesial stop, whic h displaces the archwireforward s. The arch wire is tied into the ante­rior bracket s under pressure. The com­pressed coil spring is now producing anantero-posterior expansion force, actingbetween the first molars a nd the incisors .This rapid ly tips the incisors to a more nor­mal labial inclination , enlarging the space forthe unerupted cani ne and prem olar teeth.Archfonn will be greatly enhanced an d thepatient' s appearance will , for the first time,beg in to markedly Improve.

'b)

Figure 9.11

The sa me pa tien t as in Figs 9.8-9.10. Ia-c) At 6.5 monthspost-sur gery , all inciso rs ha ve eru pted . Con ve ntiona lbrackets nave been subs titu ted for the eyelet attachments .and the 'incisor-ali gning archwires are in place. NOll' theextru sive component genera ted by these archw i rl~.

An estima te of treatment time up to thispoin t (stages 2 and 3), wou ld be between 9and 18 mo nths . New rad iographs shouldnow be taken of the unerupted canines andprem olars (Fig. 9.13) to determine the state oftheir root developmen t and to reassess thei rvertical location within the alveolus. Theabsence or earlier removal of supern umeraryteeth in this area, together ,v-ith an increase ofspace in the arch and the passage of time,may have led to an improvement in theirposition, wh ich should be recorded .

THE ORTHODONTIC TREATMENTOF IMPACTED TEETH218

---- - - - - - ----::..::...-..--=..:..::-------=-----=------------'------

(b)

(c) Cd)

Figure 9.12

The same pativnt as in Figs 9.1'1-9.11. (a.b) Ail S monthspost-surgery, 11"" incisor s 1MV<' been moved labially,aligned. and n positive overbite /overjet rela tion ship hasbeen establis hed. In th i~ parttrnlar ( "S(', the mand ibularcanines were included in this stage of treatment. Noll' thesevere mesial mot displa cement of these teeth . « ) Theocclu sa l vtcw of the mandibular anterio r teeth indicatesgross labio-Iingua l disp lacement of the roots of the lateralinciso rs and can ines . (d.e) Following 4 months of furthertrea tment, the roo l displacements have bee n corrected.Thi s was done during a wa iling period for adequa te pre­molar d evelo pment, 10 allow the initia tion of the secon dsurgical int ..rvc ntion .

Co)

CLEIDOCRANIAL DYSPLASIA

,oj

Stage 4: Vertica l correction in theposterior reg ion

Surge ry

The seco nd surgical int ervention (Fig. 9.14a)is performed at dental age 10-11, and it willleave the pa tient devoid of the remain ingdecid uous teeth. The su rgical f la ps will havebeen replaced to completely cover the eyeletattachments bonded to the unerupted pe rma­nent teeth , and stainless steel pig tail liga tu reswill be visible emanating through the suturededges of the wound.

'bl

Figu re 9.13

The sa me pati ent as in Figs 9.8-9.12. (a) A pan oramicview taken 10 months Pre-surgery- (b) A similar view 6months post-surg...ry. (e) A similar view 21 months post ­surgery.

Stric tly spea king , the scope of this surg icalprocedure, poten tially involving 12 tee th (8premolars and 4 canines in the four quad­ran ts) is large enough to warra nt endotra­chea l anaes thesia and operating theatrecond itions. However, in the more favourablecases, much improvement will have occurre dover the period of time since treatm ent wasoriginally in itiated , and severa l tee th mayhave pa rtially erupted. This may encouragethe oral su rgeon to prefer to perform therema ining exposures under local anaes thetic,one or two quad rants at a time.

THE ORTHODONTIC TREATMENTOF IMPACTED TEETH220 _ _ _ _ _ _ ___ ---'--:c==---'--~.:=:_~_'..:.:.:.:::..._.::=

,.J (b J

Figure 9.14

(a) In this pa tien t, the second su rgical intervention is typ­ically aimed ill exposing and bonding the camnes andpremolars in aU fou r quadrams, Note that onl y a mi nima lex~ure of the buccal surfaces v f th tl'Cth is performed.The alveolar bone superior to the te h is left untou ched ,as are the entire lingu al bo ne and the gingival a ttach­ments of the extracted decldueus mola r and canine teeth.(b,d The bucc al surgica l flaps have bee n su tured acrossthe ridge to the lingu al arc h. Elastic thread draws theun erupted teeth to the ri~id buccal arms of the 'incisor­aligning ' archwire.

,oJ

Orthodontics

The buccal stde pieces are now used as a rigidbeam, from which clastic thread may be tied(Figs 9.14b,c) under pressure to the 'rolled up'p igtail ligatures of the un eru pted premolarand canine teeth. Rc-Hgetion will be neededat frequent int erv als, because of the relativelypoor range of action of the elastic thread .Alterna tively, the Johnson-type archwire maybe discarded in favo ur of a plain 0.018" or0.020" arch wi rc, stretching from molar tomolar. Its long span, between lateral incisorand first molar, is flexible in the verticalplane, and the pigta il liga tures may be turned

over, to engage the wir e un der ligh t extrusivetens ion (Figs 9.15a,b). Stage 4 is expected tobe completed within 9- 15 mon ths (Fig. 9.16).

Stage 5: Correction of the axialorientation of the roots of the teeth

Orthodontics

Mesio-distal uprighting of the anterior teethwill have already occurred, if ed gewise brack­ets have been used initially, althoug h root­torqucing movements will usually need to

•

CLEIDOCRANIALDYSPLASIA

(il) (bl

Ftgure 9.15

Ia.b) The same patient as in Fig , 9.14: stages in the resol ution of the impaction of the left side carunos and premolars,using variou s types of mechanics.

(al (bl

fi gure 9.16

The same pa tient as in Figs 9.14 and 9.15. (a) Panoramic view im mediately prior to second su rgical i n t~'rv~'nli<ln (u nd""local anaesthencj. in the ma ndi bu lar arc h only. (bl Pano ram ic view 5 months later, immediately following seco nd surgi­cal intervention in the maxillary arch Ialso under local anaestheti c).

THE ORTHODONTICTREATMENT OF IMPACTED TEETH222- - - - - - - - - -------'----- '----- - -aw ait the usc of a full rectangu lar arch . Withthe usc of Begg brackets, levelling and torque­ing auxilia ries may be used du ring stage 4,once the heavier wires arc being used in thelatter st ages. However. given th e amou nt ofroo l d isplacement seen in these cases , it ismost likely that stage 5 of the treatmen twill see these movements still being appliedto the anterio r teeth, while uprighting androtating movemen ts will need to be initiatedin the premola r/canine regions, following therepl acement o f the eyelets wi th brac kets (Fig.9_17)_

At this stage, the palatal and lingual heavyarches are no longer needed, and may be cutoff with a high-speed d iamond bur. In theva rious edgewise methods, the mo lar bands\.... ill now have to be removed in any case, andnew bands adapted . with rectangular tubes.Molar expansion or rotation may now be per­formed, if desired .

TREATMENT EXPERIENCE

To date, 16 cleidocrania l dysplasia patien tshave been treated or are still in the variousstages of com prehensive orthod on tic /surgicaltreatment at ou r centre (Figs 9.18 and 9.19)(Becker ct 01 1. 1997b). It is from their trea tmentthat the Jerusalem approach (Becker et al,199701 ) has bee n form ulated and refined overthe years.

Of these cases, th ree had a total absence ofsupe rn umerary teeth, one of whom had acongenitally missing prem olar. Seve n patientshad fou r supern umera ry teeth or less andfou r other s had 6, 8, 10 and 23 respectively.Treatment of the remaining case was initia tedelsewh ere, a nd infor ma tion was not availablefor him. With th e excep tion of those found inthe incisor region, all oth er supern umeraryteet h arc recognizable supplemen tal teeth,similar to those adjacent to them. Thus su per­num erary teeth in the cani ne and premolarregions Me canin ifor m or p remolariform.Barrel-shaped supern umerary teeth havebeen the only exception in our sample, andthese have all bec-n found in the ma xillarycen tral incisor region . The presence of supple-

me ntal teeth has been help ful in our choice ofteeth for extraction, since a d isp laced toothmay be removed and the better-placed ad ja­cen t tooth aligned in its p lace, without regardto d istinguish ing which is the abnormaltoo th.

Withou t exception, the dent al age of ourcases ranged fro m 2.5 to 4 years behind thechronological age. Spontaneo usly eruptedfirst perm anent molars have bee n seen in allbut two cases, and these exh ibited supernu­merary molar tee th. Unlike other tee th, theperm anent molars appear to eru pt sponta­neously in cleidocranial d ysplasia, and itseemed reasonable to assume that , in theabsence of these obstructions, the molars ofthese two patients would also have eruptednormally. Follow ing the removal of thesupernumerary teeth, in both of these casesthe unerupted molars were exposed and asu rgical pack pla ced , to encourage hea ling bysecondary in tention and to maint ain th epa tency of the exposure. The teeth eruptedspontaneously after this p repa ratory surgicalprocedu re, and bo th pa tients were th entreated as per the above protocol.

A single erupted maxillary firs t p remolarwas present in three pa tients whose decid u­ous p redecessor had had an apical abscess .

The shape of the well-developed perma­nen t teeth, while clearly recogni zable andclassifiable in to their d ifferent too th types,showed lab ial concavities in the inciso rs,broad mesial and d istal ridges on the labi alan d lingual aspect s of both canines andincisors, and mesio-d istally excessive andbu cco-lingu ally narrow proportions of thelower second premolars. Th e roots of the suc­cessional teeth were relatively short , and theiraxial inclinations were not necessarily contin­uous w ith that of the cro wn , in both th emesio-d istal and bucco-llngual planes. Thiscreated the need for periapica l X-r'1Y monitor ­ing of the uprigh ting and torque tng move­ments o f these teeth.

In the above treatment p rotocol, th e abilityto use interm axillary vertical elas tics on thep rev iously impacted teeth was emphasized.Their valu e is seen in the enhancement o f theeruptive forces to improve ancho rage and toenco urage vertical alveolar growth. Th erefore

-CLEIDOCRANIAL DYSPLASIA

(0)

(b)

(0)

' d )

(e)

(()

Figure 9.17

(a-d A pat ient in the early part of ~1.lJi:C 5. :\'01" the severe buc(O-lingu.l] and nw"io..dista l displacement of roots ofindividual teeth . Cd-O St,IJi:C 5 close to completion .

THEORTHODONTIC TREATMENT OF IMPACTED TEETH224_______ _ _ ----'---::...:...----.::..::..c----'---~="__"__=___=::...:.::::._..

(, ) (d)

(b) (e )

k )

Figure 9.18

The Mml' ",' t il'nl ,1S in Fig 9.17. Ia-c) At the start (>f treatment. (d-f) At the complet ion of treatment. Note the tooth sized i«rcp,lncy between the jaws.

CLEIDOCRANIAL DYSPLASIA

c., eb'

Cd

225

Figure 9.19

(a-c) A patien t before lrt'atml'l'll. (<.'1 -0 At 1 year I"lsl-rdl'l'ltiol'l.

226

efficiency is no t serv ed by treating themandibular anterior tee th before the maxil­lary anterior teeth, merely I:ltX<1USC there is atime lapse of a year o r so be tw een th e normaleruption times of th ese tee th . The treatmentof the an te rior areas of both ~lWS shouldbeg in at the same time. Neverthe less, it isessential tha t the forces produced by theseve rtica l 'u p-and -down' clast ics be kept w ithinvery minimal values, since the tem ptati onex ists to use elastics thai a re too small an d toothick. Excessive extrus ive forces will br ingabout rap id eruption , bu t the clin ical crownlength of the erup ting teeth will be large,owing to rela tively lesse r ge neration of elveo­1M bone. The teeth will be ve ry mobile, an dlllay lose their vitali ty,

In the firs t sur gical in terven tion . the aim isto remove all the supernuml'rary teeth, sincethese see m to be the principal factor in thed lsp l..iccrncn t of the ad jacent pe rmane nt teethmore deeply in to basa l bone, The con tinuedpresence of these extra teeth w ill p reve nt thetee th of the normal series fro m exp ressingwhat litt le eru ptive potential they ma y have,and hence im portance is attached to earlyremoval . Th is is not felt to be th e sa me for thedeciduous tee th , Our experience has beenthat, when su pernumerary tee th arc not pre­sent in certain areas, the norm al permanen ttee th in those areas a rc not severelv d is­placed. and, while they may still not-eruptspontaneous ly. their develop ment is fai rlyno rmal. Occasiona lly, their p resence maystimula te the shedding of the d eciduous pre­decessor, and they m ..ay. in time, erupt. Forthis reason, in those areas whe re su pern u mer­ary teeth Me not found , d ecid uous tee th arcnot remo ved in the first surg ical interven tion .

Trauma to d eveloping teeth has beenshovvn to cause damage to bo th d evel opingroo ts an d the enamel of their comp letedcrowns (Bnn et al. 19R4; Ben Bassa t e t al , 1985;Zilbcrm an et al. 1986), Norma l d evelop mentand maximum eruption po tential are prob­ably bes t realized when the integrity of thedental follicles is maintained , until two-thirdsto three-quarters of the root length has devel­oped . For th ese reasons, the canine and p re­molar teeth are not exposed when thesupernumt:'rary teeth art' removed in the firs t

THE ORTHODONTIC TREATMENT OF IMPACTED TEETH

surgical p hase of the trea tment.Both in this tex t an d elsewhere (Becker et

al , 1983; Kohavi e t al, 1984), we have been atpa ins to point out our opposition to theacce pted an d es tablished practice of wide su r­gical exposure of uneru p ted teeth in nonnalcaSE'S wi th isola ted impacted tee th (Lap pin,1951; Lewis , 1971; vo n dcr Hevd t, 1975).Given the underdevelopment of the maxillain the an te ro-posterior plane and of both jawsin the vertica l plan e in cleidocranial d ys pla sia(Kalliala an d Taskin en, 1962; Zegarellt et al,1978; Shafer et al, 1983), and the fac t tha t "very large nu mber of unerupt ed teet h are pre­sen t within th e bone and largely eliminatingthe sponglosum, the w ide remova l of the cor­tical plate (Smylsk i et al. 1974; Hall ClodHyland , 1978; Richardson and Swinson 1987;Bchlfclt. 1987) would appear to be wastefulan d compromising.

In the Jeru sa lem approach, access to theteeth is gained by a m inima l opening in thecortica l pla te, immedia tely overlying theteeth. The size o f the opening is determinedby two factors:

(a) exposing a surface la rge enough to aero­modate a small eyelet attachment;

(b) enlarging this to th e minimum size thatwill a llow the surgeon to ac hieve haemo­stas is for long enough to allow the bond ­ing p roced ure to take place in aco ntamination-free micro-environ ment.

The re is no reason to remo ve fu rther bonean d certainly not to reduce the vertica l heigh tof the ad jacent cortical p late. The co mpletesurg ical flap s arc sutured back to close off thesurgical field fully, an d healing is by primaryin tention, which would appea r to offer ahealthier and more rapi d per iod of heali ngand to promote a speedi er and more generousresponse on the part of the alveol ar bone(Laskin, 1985), The final pe riod ontal s ta tus ofthe teeth will also be more norma l (Becker ctal. 1983; Kohavi el al, 1984).

Deeply d isplaced teeth may th us be d rawnocdusally through the overlying bone . whichoffers no real resistance to the rnccharucallvass isted eruptive force: New alveolar boneaccompanies the erupting tee th as theyprogress towards the occlusal plane, in a

CLEIDOCRAN IAL DYSPLASIA

manner s imil ar to that occu rtng with normal,u nassisted eru ption in the normal pa tien t(Becker ct al, 1983; Kohavi et ,11, 1984). Thiswill en hance the vertical height of the alveo­lar procesSt.'S of the two jaws, incid ent allydeepening the labial and lingual su lci an dim pro ving the overa ll facial p roportions.

In the other two methods, the need tomaintain patency of the exposure and visualcontact with the un erupt ed tee th d icta tes thatthe bo ne level must be pared down to that ofth e deepest tooth. This clearly includ es thereduction of both the lingual an d buccal co rti­cal plates to this level - an d this in a patientwhose alveolar processes are already ofreduced height, because of the sy nd rome.

PATIENT VARIATION

Similarities are seen among all of the patientssu ffering from cleid ocra nial dysplasia, butthere is a varying degree of expression of thevarious characteris tic features of the d isease,tog ethe r with m.l ny other sporad ic p henom­ena that have been repor ted to occur with thecond ition. Eru pted pe rm an en t incisors aresometimes seen, and these may elimina te theneed for the 'incisor-eru p ting' initial heavyarchw lre, in one or both arches. Instead, thetreatment may begin w ith the levelling phasewit h the modi fied Johnson twin-wire arch.

Some patients make their appearance forthe first time at an ad vanced dental age, whenroot apex closu re has occu rred in most of theeru p ted an d un eru pted teeth. Obviously,there is no d evelopmenta l determinant todi vid ing the treatment in to the above­mention ed stages , althou gh it may still beadvisable from a strictly mechan ical point ofview. It is difficult to d esign an appliance tha tm ay efficiently extrude teeth in several areasat the same time. Never theless, the inclusionof the canines with the an terior tee th mayhave some merit in these cases.

At the completion o f all the treatment andthe p lacement of retainers, new radi ographsshould be taken to check for the develop mentof recurrent su pe rn u mera ry teeth, whichsometimes occurs in the 14-16-year-old

Figu re 9.20

Pano ramic radiog raph of a palil'nl 12 Yl',l"" after allappliances were removed. A newly developing su pcmu­me rary pre molar loot h is noted.

patient (Fig. 9.20) . At this po int, any decisionregard ing the extraction of such tee th isstrictly a sur gica l one (Bec ker c t al, 1982;Becker and Shteyer . 1987). When suc h teethare identified a t this late s tage, their extrac­tion is no lo nger an orthod ontic decision,since fu ll align me nt of the teeth has beenachieved and su ita ble retention will preventan y adverse effects. Such factors as locationand accessib ility. incip ien t resorption ofne ighbouring erupted teeth , and cysts will allinfluence the su rgeon rcgerdtng the necessityand timing of their extract ion .

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THE ORTHODONTIC TREATMENTOF IMPACTED TEETH228------------'-=-=----=----=--=-=----~=----::..:..="--=-'-

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Seow WK, Hertzberg J (] 995) Den tal devel op­ment an d mola r root length in chi ld ren withcleidocra nial d ysplasia . Pediatr Dent 17: ]01- 5.

Stewart RE, Prescott GH (ed s) (1976) OralFacial Genetics. Mosby, St Lo uis.

Tachd jian MO (]990) Pediatric Orthopedics.2nd edn, pp 840-4. Saun ders, Philadelphia .

Trimble LD, West RA, McNeill RW (1982)Cleidocran ial d ysp lasia: comprehensive treat­ment of the dentofadal abnormalities. j AmDelli Assoc105: 661-6.

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von der Heyd t K (]9 75) The su rgical uncover­ing and orthodontic positioning of uneru ptedmaxillary canines . Am / Orthod 68: 256--76.

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Zachri sson au (1977) Clinical experience withdi rect-bond ed orthodontic retainers. Am jOrtJl/lit 71: 440-S.

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Zilberman Y, Fuks A, Ben Basse t Y et al (1986)Effect of trauma to pr imary incisors on rootdevelopm en t of their permanent successors.Ped Dellt 8: 289-93.

Index

Page num Oer'l in itaIIic refer to theillustr.l tions

active ~l;aul arches 121-2. / 21active remova ble pbites 18 1- 2. /88Adam's clup 166. 18 1ad...1tpatienud~is 178-80m:;mqement 180-1tempora ry pros the ses 18 1- 7

alignmentgroup I anines I 17. 1/7group 2 unines 120-3. 120group 3 can ines 131-4grou p " canines 134grou p 5 anines 135-9spootaneous 62

anchor tee th 187anchorage

implanu 196uniu -«. 109. 120. 167

Angle'sClan II malocclUSion 10ankylosis29. 35. 'IS. 8 1

crown resorptio n 17 1-2apical roo t dilaceratio n 73appeara nce 11)-11. 62-3 . 202. 211appl iance s 109

see also mechanotherapyactive re movable plate 181-2Adam's clasp 166. lS Iadult patients 193, 194auxiliary labial w ire 122- 3. / 24auxiliary springs 37 . 38, 46-9ballist3 37, 121, 112Begg brac kets 65. 222box elast ics 72. 215-16bracke ts 46-7, 46buttons 77. 81, 170early mixed dentit ion 63-4ectopic first mo lars 166Edgewise bracket! .016, 65. /59er uptio n 113extra -ora l headgear 157, 169'finger sprinc /64fixed versus remo vable 166

flipper (Spoo<1) dentures n . 179. 181.187

Johnson 's (mod ified) twin-wire archmaxillary central incisors &4--8.

67-70root dilace ration 7.01. 78

magnet! SO, 50mandibtllar second molars 167. 168multi-bncketed 44. 190orthodontic bands .016removable 123separato rs 166Siam"'se bracketS 46. 167threaded pins 45--6. 45

arch lengths 111archfo rm 110--11. 217archwires

anchorage eases 44buccal 68elasuc di spla~ement 49incisor-aligning M. 213. 2 16--17. 2/ 7incisor-erupting 2I3. 2/3, 2!.oI , 2/5mandibular canines 15.01palatally di sp la~ed ~an;nes 111- 12toot h transposition 190

attachments .01 4-8bonding 30, 31. 36-40. 38butto ns 77.81extra-oral anchorage 196eyelets 37. 39, 47-8, 47

group I canines I 18- 19gro up 2 canines 120group 3 canines 130-1

Goshgarian bar 186-7, /88- 9auxiliary labial wires 122- 3. / 24auxiliary spr ings 37. 38. 48- 9. 120--3.

/2 4

ballista 37, 12 1, / 21bands, orthodontic 46Begg brackets 65. 222Beggtech nique 111- 12Il<! It.ut-Hamburg appro ach 205-7bonding 46

acid-etch 159

;agents39atta chmenu 30. 31. 36--.0\{). 38unfilled resin 196

boeochannelling 26cleidocranial dysplasia 207height 71support I 13-1.01. 1/4

bolt e lastics n .215-16bnckeu . o rthodont iC 46-7, 46bridge abutment 193. 196buccal arches 187buccal impaction

maxillary a nines 151-3. 152-3surgical e"posure 30-2. 3/ . J2

buccal traction 128. /32-3buttonholing 32. J2butto ns n. 8 I. 170

caninesCT scanning 22deciduous

cynic changn 97-98 , 97e"traction 102. 103. 104morbidity 96root non-resorption 90, 9 /

development 86-8, 87",ruptio n 6. 88mandibular .ol, 154-6 . /H. 155, 156,

/88-9maxillary 89

eruptio n 26impa ~ti on . buccal 151- 3, 152- 3inspection 100missing 186-7palatal /5radiography 21root developm ent 4

palatalclassification 112-47displacement theories 88-96impaction 86

complications 96-100diagnosis 100- 1""'tra ctio n I I I, 113

INDEX232 --.::.:::::

cont'dgroup I 115-19,116-1 7group 1 119- 27. 1/ 9, 126-7gro up 3 128-3'4. /29group ~ 134-5. /36-7groo p 5 135-9. /38. 139grou p 6 139-46heredity 95- 6mectu.oothelOlp~ 110-12, I so.

1/ 1.//2prevalence 85-6treatment. tim ing 10 1- 9

radiography / 9. 101t rea tment, pre~tiYe 102-5

cen tral incisorscongeniW . bsen<:e 53di~5;S S~ 1

dilaceration 2 /. ss-e.72-6erup tion 53prognos is 71-6root~elopment 55. 56. 58. 72-6lpOIce Ion 8. /6~.ttml!flt 61-82

centnlma ndlbular incisors 4-Schildre n

central inci$Ol"$ 53. 54. 62detlD.l age I-t.. 2. "dq,gnosis 8orthodo ntic separ.llton 166surgical interventio n 9traumatic injury 55-9 , 68-70

c1eidOCl7onial dylpl.tsia 199-200.200.20/ ,202

Belfast -Hamburg appro4lch 205- 7diagnosis 211Jenosalem approach 207-9. 211-22.

226lo ng-t erm retentiOl'l 2 10pat ient variat ion 227pnil'l'1t well·being 209. 210To ronto-Melbourne appro ach 204-5treatment 202-4, 222, 225. 226-7

computed to mography (e T) scann ing 22,23. 2001

palatally impacted canines 99cross-bite 182cro wding 7. 8. J2

c1eidocraniai dysplasia 209- 10extraction 111 - 12mandibular canines 156mandibular second premolars 157maxiilary f,rst mo lars 165palatally impacted canine s 89-90. 89.

102crowns

amputation 76calcificat ion 4dilaceration 56. 73-4. 75resorption 33

see also replaceme nt res~ption

ankylosis 171-2impaction 169-70

paiatally impacted canines 98, 98CT see com put ed toroograp hycYSts

de ntigerous 8. 98, 174, 176palata lly imp;acted canines 97. 97,

"mars upialization 174

deciduous teethcyst ic changes 97-98. 9 7extraction 102. 103, 104reClined 3, 3. 5, 8. /0

cleidocranial dysp lasia 202, 107mandibular second prem olars

157-8supernumerary teeth /6surgical intervention 17-tl

dena l age 1--0. 102. 211denta l foiliciM

cystic change 97. 98. 99surgical exposure of imp;act ed teeth 9.

33-5.34de l'lQl history 59dentigerous cysts 8, 174. 176

p;alatally impacted canines 97. 9 7. 99d~eloprnent

canines 86-8. 87denCll age 1--0. 33denal fo llicles 33dilaceration 55-7

dilacera tionapical root 13central incison 2/. 55-8. 60--1, 66,,2-<>

Edgewise brackets 46. 65. /59elas tic ligat ures 47- 9. 48, 49, 72elastic traction 193-96enucleation 174eruption

can ines 6, 26. 88delayed 3, 6-7, 53, 61for ced 113- 14full flap closur e 31-2maxillary central inciso rs 6, 53prem ature 6. 9pr imary failur e of 17 1spontaneous 62surgical intervention 26-8, 27t ract io n 109

etching 38. 130. 196exp osure 27--8, 2 7,28, 38, 109extra-o ral anchorage 196extra -oral headgear 157. 169extra-o ral rad iograp hy 17extra ctio n

cro wding 111-1 2de<iduolJS canines 102. 103. 104denLlI age 2first premolars 102, /05infraocclusion 16 1latera l inciso rs 103--5. 106

mandib ular seco nd pr eroolars 157palatally impacted canines I I I. 113preventive trea tment 102-5, 103,

104, 105eyelets 47-8. 47

atta chment 37, 39Srou p I canines 118-1 9s roup 2 canines 120s roup 3 canines 13e-1

facial appea ranc e 10--1 1. 62- 3. 202.211

'finger' spring /64flipper (spoon) dentures n. I~. 181.

18'follicular sacs 97. 98. 99free-end edentulous saddles 193

gold cllain ligatu res 47Goshgarian bar 186-7, 188-9",idance theory 90-3

hard tissue obstnlctions 28-9headg ear 157, 169healing, by sKondary int ention 9he redity

cleidocranial d'y$plasia 199guidance theory 9s-6. 95infnocclusion r71. / 73

Hertwigs root sheath 57. 58. 58

Impactionbuccal 15 1- 3. 152- 3

surgica l e xpos ure 30-2. 3 1. 32co mplicatio ns 58crown re sorption 169-70diagnosis 6-11, 9disguise 178-80guidance theory 90-3hard tissue ob stnJctiOf128-9negle<:t and disS"ise 178-80obstructed 71-2odoraome s 86palatal

complitations 96- 100diagnosis 100- 1grou p I canines 11 5- 19, 1/ 6-17grou p 2 can ine~ 1 19~27, 1/9 .

/ 26- 7group 3 canines 128- 34, 129group 4 ceooes 134-5, 136- 7group 5 canines 1 3 5~9, /38. /3 9group 6 canees 139--46heredity 95-6me chanother apy 110- 12, , 10. III,

112prevalence 85-6t reatme nt t iming 10 1- 9

r.ld'osraphy 13- 24surgical ex posure 8-10. 25-'11tra umat ic causes n-82

implants 180. 196

INDEX

incisor-aligning archwir('$ 6-4, 2 1),2 16-17. 2 / 7

incisor~rupting archwire$ 2 13. 2/3. 214.115

incisorscentnl

dilacented 2 1rTWCi llary

arrested root development 58co neenita l absenc e 53diagnosis 59-61eruption 53obs tru aive causes 53--5, 71-2prognos is 71-6space los s 8. 16tra umanc caus es 55--9. 72-5treatmeM 6 1-82

min ing 182- 5root develo pment 4-S

eruption 6, 53latera l

extraction 1 03~5. 106maxillary 4-5, 10palatally impaned canines 9 1-3. 92.

94.99, 110, 110root developmen t 4-5. / 0root re rorption 141. 142-3.

144-5. /46. /47-8late 98-100. 99

maxillary 87 . 14 7-8. 19/-JinlTaocciusion

deciduous teedlI 59-6 1.1 62. /63.164-5

extn<:Von 161non- ankylotic In. 174perma nent tee th 17H , /71, 172surgia l e ltposure 29

intru sive luu tion 58-9. 76-82, 77--lJO

jer usaleen approachdiagnosis 21 Iormodontic~ 2 /2-/3. 213-1 8. 214.

22G-2, 223--4 •surgery 214, 219

[chr ac n's (modified) tw in-wire archcleidocranial dysplasla 213maxillary central inciso rs 64-5, 64.

66, 67-8,6 7, 68-70root dilaceration 74. 78

lasso wires 45. 45lateral i nci ~Ol's

exrra ct ion 103--5, 106palatally impacted caoees 9 1- 3. 92,

94,99.1 10. I / Oroot deve lopme nt 4-5. /0root resorption 98-100. 99. 111.

/ 41-8lateral mandibular incisol"$, root

de~lopment 1. 5b ter.lllopen bite 16 1. / 63lesions, so ft tissue 28

ligatu reselu Dc18-9, 48. 49, ngold chain 17p~1 17-8 . 214-15

sllnp hot ebstic 49. 1/ 6. 118stainless n eel17--lJ

magnets 50, 50malocclusion 10. -41mandibles

arch. r.lIdiogr.llphy 11. / 4a nines 1. 154-6, 154-6, /88-9removable appliance 123~econd molars 167. 169~ecood premolan 157, 157-9, 158,

160marsupialization 174maxilla

ante rior occlusa l 14. /5arch radiography 14. /5canin es 89

erupt ion 26impact ion, buccal 151-3, 151- 3inspection 100missing 186-7palata l /5r;adiogr;aphy 2 1root developm ent 4

centr.l l incisorsarrested root de~lopment sacoo gen ital abse nce 53diaenos is 59-6 1prognosis 11-6space Ios ~ 8. / 6treatment 61-82

first molars 165--7. 175-6first premolars, root development 4inciSOI"$ 8 7. /47--8latenl incisors. root development

+-5. /0second premolars 16 1. 161. 163,

164-5mechanotherapy

see also appliance scleidocranial dyspla$ia 208-9eruptio ns 62group 5 canines 138- 9, /38palatally impacted canines 109- 12timing 105, 108-9

medical hiSto ry 59mesial crown displacement 118--19molar bands 187. 188. 190molars

elastic traction 193-6eruption 6mandibular sec ond 167.1 69root development 4--5second deciduo us 159--61third 193. 196

mosquIto forc eps 39

odontome~ 7. 5.04, 60O nts pro jection /5onl hygiene n. 108. I 12. 125, 176, 211orthophosphoric acid 36ovNjets 182

palatal ippro<lch 131. /3 'palau l arch 37. 65, 187, 190palaul displacement 88-96palatal impaction

canines 86classif,catio n 112......7complication s 96-1 00diagno$i$ 100-1he redity 95-6prevalence 85-6treat ment 110-12. I/ O. 1/ I. 112tr eatment timing 101-9

palatal mucos a 32-3palatal roo t displacement 119, 125palpation 59-60,100- 1patients

adultsd i agno ~i ~ 178-80management 150- 1temporary pros thes es 18 1-7

appear.llnce 10-1 1, 62-3, 202, 21 1children

diagnos is 8orthodo ntic separ.llto<'s 166surgical interwmtiQn 9tr.l umatic injury 55--9. 68-70

dental age 1---6. 1. 4histo ry 59mOtivation IG-IIpsychologica l well-being 209, 210

pe rmanent tee th. lat lHlev eloping 6piguilligature s 17--lJ. 2 14-15premolars

deve lopment S. 6. 7extraccon 102. 105impacted 10mandibular

abnormalorienution 157- 9. 158./5 9

crowding 157extraction 157late_developing 160

maxillary 16 1, 162. /6 3. 164--5root develcpmenr e

movement 135preventive treatment 102- 5prosthetics

deidocr.lln ial dysplasia 203tempo rary 181- 7. 190

psychologiCiI well· being 209. 2 10pulp nec ro sis 8 1. 97

r.lIdk ular cysts see dentigerous cystsr;adiogTaphy

a nines 19, 10 1central inciro rs 60--1

INDEX234---------- ----------"=confd

cephalometric 20. 20. 2 / , 22cleidocranial dysplas ia 200. 201crown reso rp tion 169de<iduous teeth 8. 9extra -ora l 17mandibular arches 1<4 . ' 4nundibul ar a nines 15<4

nuxillary canines 2 1maxillary firs t molars 165maxillary second prem obn 16 1occlusal 14-1 6. / 4. /5odon tomes 60p.lrall:u method 17- 2l 1Bpenapia.18. 1l -1 4,/6roo t resorption 140views at right-aneles 1&-22. / 9. 20.

21,22~pbcement re5o.-ption 8 1. 98. 169

seealso anlo:yIosis~iOIi>tJon

see also ankylosIScrown 33. 98. 98. 169- 72incisort 98-100. 99. '4 1, / 42-8replacement 81. 98. 169

rcc r:axial ori entation 220. 222development 4-5. /0

OlITflt ed 58canioes ..

dentalace 2. 3-5, Jimpacted centrlll incisors 55. 56.

58.72-6dilaceration 73displacem ent 119. 125Hertwigs Illeam 57. 58. 58non-resorp tion 90. 9 1,1 14- 15orientation. cor rectio n 75resc rpucn

central inciso rs 98- 100. 99. ''' 1./4 2-3. /4 4-5. 146

lat er al incisors 141, 147-8p~lnOi lly impOicted canines 140

rotati on 118, 120, I2S

secondary intent io n, healing 9

separators, orthodontic 166Siamese brac kets 46, 167slingshot elastic 49, 1/ 6, 118soft tissue 28, 55, 72soldered palau l arc hes 182, / 83. 184--6space closure 153space opening 105, /07, 110, /1 0spongiosum 207su inless steel ligamres 47-8supe rnumerary teem 7, 5 3~5. 202. 207supplemen tal teem 199surgery

atD.chm ent bo nding 36----40cletdoc......ial dysplasia 20 3-9de ntigerous <:y5ts 174, 1766'Upti on s 26-8, 27exposure 27-8. 27.28.38group I canines 117groop 2 c,mi nes 119- 20gro up 3 canines 128-34group 4 canines I Hgroup 5 canines 135impaa ed teem 8-10, 25. 31)..-5, 41mandibular canines 15-4mandibular second ....emolars 157wft tissue lesions 28timing 9--10, 207-8

surgical flaps~cal repositioning 30. 31. 109. 128closu re 3 1-3. 35, 47

mird molars 193, 196m readed pins 45-6, 45Tip-Edge technique 11 1-1 2teeth buds 54--6tooth developm em

canine s 86-8, 8 7de ntal age 1--6, 33den ta l follicle 33dilaceration 55-7

tooth germ displacement 95. 96, 96,97

tooth position, parallax method 17- 22,! 7, 18

Toromo -Melbourne approach 204--5t raction

attachment bond ing 40buccal. grou p 3 canines 128, 132-3de ntal follicle 33-5direc t versus two-stage /3/elastiC 193--6mechanotherapy 109orthodontic 33- 5.40

tra ns-palata l bars 186-7, /88-9tra nsplantation 203tra nsposition 138-9./38. 156, 190tra uma

u.nines 72-72centra l incisors 55-9children 55-9, 68-70intrusive luxation 58-9, 76-82. 77-410soft tinue 55

tr en ml!fltsee aiSlI appliancesAn&fe's Class II malocclusion <Hattachments «attltudfl to 61-3. lOB, 141. 18 1bands. orthodontic 46bra ckets. orthodontic 46-7. 46buttonholing 32.32duration 43--4elastic ligature 48-9, 48I!flucleation 174eyelets 47-8, 47impacted intisors 63-7 1lasso wi res 45. 45ligatures

elastic 48-9, 48. 49, 72gold chain 47pigui147-8,2 14-15slingsl>ot elastic 49, /16, 118sta inles s Steel 47-8

magnets 50, 50pre ventiv e 102- 5m readed pins 45--6. Htiming 6 1. 10 1- 9

tr ue (vert e"') occ lusal IS, / 5runnel approach 128, 130

well. being. psycho logical 209, 210Whitehe ad's varnish 9, 25, 159

B1BUOTI"' ~ I"'\ I .l e:: n~ L'tnll""O~S'TE::r--t ...: :;1 "': '!

U ,r' ,8 . 0 ' T--:~ l r""'L'JG I~

1 , ru ) : ,- ~ ,, : 1 . -. ..r.~" '(

92 12 0 :VIONTROU G E