Current Concepts provides the opportunity for invited ir-dividLals to express their opinions on selected currenttopics oí interest in the field ot dentistry. The commentsexpressed herein represent personal opinion and notthe positions of Quintessence International.

The Hopeless Tooth:When is Treatment Futile?

MAJOR FACTORSAFFECTING THEPROGNOSIS OF THESTRATEGIC TOOTH

J0H^fW. HARRISON, DMD, MS

TIMOTHYA, SvEC, DDS, MS

When ¡s Treatment futile? The question appears deceptively simple, but theariswer ¡s surprisingly complicated. Without some qualifications, the answerwould also be far beyond the space constraints placed on the authors. Forthis reason, we will respond to the question with the following assumptions:

1. The derital practitioner has superb diagnostic, treatment planning, andtreatment skills,

2. Posttreatment management of oral hygiene is excellent.3. The involved tooth is a strategic tooth and, if successfully treated,

would become a functioning component of the patient's masticatoryapparatus.

4. There are no systemic contraindications or economic restrictions af-fecting treatment.

The tooth, rather than the entire dentition, will be the focus of our concern.The hopeless, untreatable tooth of the new millennium is far different

from its counterpart a half century ago. The advances since the 1950s and'60s in technology, biomaterials, delivery systems, surgical and nonsurgicaltherapies, scientific evidence, and access to continuing education havebeen remarkable The modern dental practitioner can accomplish whathis/her predecessor of a few decades ago would have considered impossi-ble But the hopeless tooth still exists.

There are two major factors that most commonly relegate a strategictooth to the "hopeless" status' restorability and periodontal support. Thetooth that cannot be restored or that has inadequate, unmanageable peri-odontal support is hopeless.

846 Volurjie 30, Niimhor ^2. 1999

D I Hariisnn is Professor ot Endodontics at Bay-lor College ot Dentistry, Texas ASM tJniuersilySystEm, in Dallas, Texas. He lias publislied en-lensii/ely in national and international journals.He IS 3 ÜLplomate and tormer President ol theAmerican Board of Endodontics and is coau-tfior ot a major lexlbook on surgical endodon-tics.

Dr Sïeu is Associate Protessor in the Depart-ment of Stomatoiogy at tlie University of TexasHeaith Science Center in Houston. He is aDiplomate ot the Amencan Board of Endodon-tics and an investigator for the Houston Bioma-terials Research Center.

Restorability. With modern restorative materials and techniques, mostteeth can be restored Even teetb with carious lesions causing destructionof most of the coronal tooth structure are now restorable. Extensive coro-nal destruction frequently requires endodontic therapy, and/or crown-lengthening therapy

Endodontic therapy. Restorative requirements often dictate endodontictreatment of the involved tooth. Restoration may require a post and core,superseding other considerations (eg, the status of the pulp) and renderingpulpal diagnosis essentially inconsequential The post and core function col-lectively. The core replaces lost coronal tooth structure and provides reten-tion for the crown. The post provides retention for the core. The post mustbe designed or selected to prevent the possibility of root fracture from in-sertional or functional forces The crown restores function and protects theremaining root and coronal structure from decay and trauma.

Clinical dilemma. If a post and core are not required for restorative pur-poses, the most frequently encountered clinical dilemma involves the deci-sion to treat or not to treat endodontically prior to coronal restoration. It isfar easier to perform root canal treatment before crown preparation and fab-rication, to allow better visibdtty, easier access, greater instrument control,and less likelihood of perforation, ledging. or other untoward treatment se-quelae. In addition, patients generally respond negatively to the necessity of"making a hole" in their new crown, especially when informed of the possi-bility of porcelain fracture in porcelain-fused-to-metal crowns. The decisionnot to treat endodontically prior to restoration is usually based on one ormore of the following factors: (1) the patient has no symptoms, (21 there isno periapicai radiolucency, and ßj there is no pulpal exposure after caries re-moval. Each of these factors may lead to false conclusions and poor clinicaldecisions that may be regretted later.

Symptoms. It is essential to carefully artaiyze all subjective informationand obiective findings to obtain an accurate diagnosis of the pulpal status. Ifthe diagnosis is either pulpal necrosis or irreversible pülpitis, endodontictreatment is indicated. If the diagnosis is questionable (ie, between irre-versible and reversible pulpitis), the experienced practitioner will wisely de-cide to initiate endodontic treatment If symptoms such as moderate to se-vere thermal sensitivity and/or masticatory sensitivity exist, endodontictreatment is clearly indicated.

Pulpal necrosis presents many chnical faces and therefore can be a realchallenge to diagnose. Pulpal necrosis can cause such severe, spontaneouspain that the patient seeks immediate palliative treatment (many times mthe hospital emergency room). It can also present with no symptoms andno prior history of symptoms. Most practitioners have observed the latter bydiscovering an obvious periapicai radiolucency associated with an asympto-matic tooth. When apprised of this objective finding, the patient often hasdifficulty believing that a problem exists Therefore, the absence of symp-toms IS not adequate justification for the decision not to perform endodontictreatment prior to full coronal coverage.

Periapicai radiolucency. The absence of a periapicai radiolucency does notindicate that there is no periapicai inflammation resulting from pulpal break-down. The presence of a radiolucency suggests pulpal necrosis with exten-sion of the pulpal disease into the penapical tissues (the most common ofseveral differential diagnoses requiring evaluation).

Radiographic evidence of periapicai bone loss does not appear untilbone destruction occurs at the junction of cancellous and cortical bone.'The anatomic relationship of the root apex to the adjacent bucea! or lingualcortical plate dictates the amount of bone loss that must occur before it isobservable radiographically. In maxillary lateral incisors, mandibular ante-riors, and certain roots of maxillary and mandibular premolars and molars.

Qiiinli.847

If the diagnosis isquestionable, the

experiencedpractitioner willwisely decide to

initiate endodontictreatment. If

symptoms exist,endodontic

treatment is clearlyindicated.

periapical bone loss can be considerable v^iithout radiographie evidence o(a radioiucency.

The presence of a periapical radiolucency with diagnostic evidence of pul-pal necrosis indicates the need for endodontJc therapy. The absence of a pe-riapical radiolucency means nothing.

Pulpal exposure. There is a common misconception within the dentalprofession that the only important dimension of a carious lesion is thedepth of penetration. This reflects a lack of understanding of pulpal patho-sis and Its etiology. It also suggests that many dentists do not understandthat pulpal iniuries are cumulative. The fact that there is no pulpal exposureIS meaningless.

Pulp never retums to a normal state after the first carious assault. Furtherpulpal injury occurs with cavity preparation and with insertion of any restora-tion replacing coronal tooth structure. Each succeeding carious attack,caries removal, and restoration adds its damaging effects on the pulp As aresult, pulp that has suffered through several carious lesions and severalrestorations may not be capable of withstanding the damage inherent incrown preparation (There should be no delusion that coronal preparation ofanv type is not damaging to the pulp,) Unfortunately, obvious symptoms andsigns of pulpai breakdown, a result of cumulative injuries over many years,may not become clinically evident until long after full coronal coverage.

The wise practitioner considers the cumulative effect of injuries to thepuip (similar to the cumulative damage of irradiation to tissues) when mak-ing the appropriate clinical decision regarding the need for endodcntic ther-apy prior to full-coverage restoration of the tooth with moderate to severecoronal destruction.

Success rate in modern endodontics. The success of endodontic therapyin the new miiiennium will be approaching 95%, a phenomenally high rate incomparison to several decades ago. The technological boom in endodonticshas provided the general dentist and the specialist with methods and instru-ments that allow successful treatment of teeth with calcified chambers, cal-oified canals, severe root curvature, ledging, resorptive defects, perfora-tions, and canal blockage. With enhanced vision, direct lighting, use ofultrasonics, nickel-titanium mechanical and hand instruments, and multipledelivery systems for obturation, almost all teeth requiring endodontic ther-apy can be successfully treated. In fact, the two primary causes of endodon-tic failure are actually due to restorative and periodontal failures,

Crown-iengthenmg therapy. With extensive carious destruction of coro-nal tooth structure, crown lengthening procedures are frequently indicated.The purpose is to allow sufficient exposure of tooth structure to preventcrown margins from impinging on the biologic width of the cervical attach-ment apparatus. This may be accomplished by periodontal surgery or ortho-dontic extrusion,

Periodontal health is essential for long-term success of the restoredtooth, and the effect of the planned restoration on the cervical attachmentapparatus must be considered. Violation of the biologic width by the crownmargins invites failure due to the increased potential for progressive peri-odontal disease This problem is easily solved by periodontal crown-length-ening surgery, which essentially moves the cervical attachment apparatusapically prior to crown preparation. The same result can be obtained by or-thodontic extrusion, but this treatment is more complicated and requires alonger period of time.

Periodontal support. Periodontal disease may oause destruction of theperiodontal support of a tooth to the extent that it becomes a hopelesscause. But modern treatment and maintenance capabilities have madetremendous advances in allowing the severely damaged, penodontallyinvolved tooth to continue as a functioning member of the masticatory

Volume 30, Number 12, 1999

Radiographicevidence of

periapical bone lossdoes not appear until

bone destructionoccurs at thejunction of

canceilous andcortical bone.

apparatus.' The periodontally hopeless tooth, similar to the restorativelyhopeless tooth, will be quite different in the new mJllennium as comparedto Its counterpart in tfie mid-20th century.

Major factors affec:ing prognosis. Among the determinants most com-monly used in the assessment of the prognosis for a tooth with a diseasedperiodontium are: (1) pocket depth, (2! pattern and degree of bone loss, (3)degree ot mobility, and (4) crown-root rafio In addition, the practitionermust be able to idenfify and eliminate (or control) the etiologic factors re-sponsible for the periodontal destruction. (Vitality status of tfie pulp is a po-tential etiologic factor that always requires evaluation.) Pocket formation,bone loss, mobilitv, and an unfavorable crown-root ratio are reflections ofthe normal progression of periodontal disease.' If the history related to eacbof these factors can be determined, the rate of progression of the diseaseand the age of the patient can be used as important considerations m deter-mining the prognosis. The older the patient, the more favorable the progno-sis for any degree of periodontal destruction,

Periodontal pockets. The depth, size, and location of periodontal pocketsprovide a preliminary assessment of the extent of disease. In general, thedeeper the pocket, the poorer the prognosis. If the deeper pocket accu-rately reflects greater loss of alveolar bone, the problem is more seriousPockets associated with single-rooted teeth usually respond to treatmentbetter than those associated with multirooted teeth, especially if the furca-tion area is involved. The presence of furcation involvement does not indi-cate a hopeless prognosis. However, involvement of the furca area by peri-odontal disease causes two significant problems: (V limited access forscaling and root planing and for performing surgery and (2) limited accessfor plaque removal by the patient. The more accessible the pocket for treat-ment, the better the prognosis. Deep proximal and circumferential intrabonydefects do not respond predictably to treatment.

Bone loss. The greater the bone loss, the more guarded the prognosis.As bone loss approaches and exceeds 50% and as the pattern of bone lossbecomes more irregular, the prognosis worsens. Irregular, vertical, andtroughlike intrabody defects adversely affect prognosis, especially if the in-terradicular bone of a furcation is involved. If the roots are widely spreadand root concavities are minimal, furcation involvement is more amenable toroot resection procedures (after endodontic therapy when possible) andother types of corrective surgery. If the entire interradicular septum hasbeen lost or if the roots converge or fuse at or near the apices, the progno-sis is hopeless.""

In the past decade, a new form of periodontal treatment has proved tobe remarkably successful. Many teeth previously regarded as hopeless aresalvageable via guided tissue regeneration (GTR). Badly involved class ¡I fur-cation involvements, large three-walled intrabony defects, and osseouscraters that wete nontreatable have become predictably treatable. Recentadvances with extensive GTR procedures have made most two-walled in-frabony defects routinely treatable. Multiple-tooth GTR procedures are be-coming increasingly successful, even groups of teeth with more than 50%loss of attachment can be maintained with regenerated suppoa."

An isolated vertical intrabony defect may result from a fracture extendingvertically and apically along the root (vertical root fracture). This type of frac-ture may be due to occiusal trauma {especially in teeth with restorationsinvolving the mesial and distal marginal ridges), post placement, or exces-sive compaction (condensation) forces during root canal treatment -̂ Theseare difficult to diagnose because they mimic other conditions, includingfailed root canal treatment and periodontal disease. If only one root of amultirooted tooth is involved, root resection is an option Otherwise, verticalroot fractures have a hopeless prognosis.

0 u i nres s prmw-ti-)tiimn litinnt 849

The greater the boneloss, the moreguarded the

prognosis. As honeloss approaches andexceeds 50% and as

the pattern of thebone loss becomesmore irregular, theprognosis worsens.

Mobility. Teeth with deep pockets and bone loss have a more favorableprognosis if they are stable rather than mobile. Mobility may be caused byinflammatory changes in the periodontal ligament, trauma from occlusion,or loss of alveolar bone. Mobility caused by inflammation and traumatic oc-clusion are often easily corrected, but mobility caused by loss of alveolarbone support presents a much greater problem. Teeth with 50% loss of at-tachment and 2 to 3 degrees of mobility have a very guarded prognosis,perhaps hopeless. However, if the cause of mobility can be eliminated andthe mobility can be controlled (by splints, fixed prostheses, etc), then theprognosis is bettet in general, a direct association exists between increas-ing mobility and worsening prognosis. If a tooth is depressible, the progno-sis is usually hopeless.

Crown-root ratio The more favorable the crown-root ratio, the better thetooth can withstand masticatory forces and the better the prognosis. Teethwith short, slender, or tapering roots have a poorer prognosis than thosewith long and broad roots. Multirooted teeth usually resist traumatic forcesbetter than single-tooted teeth. Flared moiar roots give better support thanfused, conical roots. Broad occiusai tables and large crowns can contributeto increased mobility. The support of the tooth is determined by the heightof the alveolar crest and the iength and shape of the root. Canines can with-stand loss of support better than iaterai incisors by virtue of their longerroots and root concavities. Maxillary first premoiars show early mobility be-cause of the tapered roots.' Some patients have teeth with short roots andothers have root résorption, both of which may be the result of orthodontictherapy. Such teeth are less resistant to excessive occiusai forces,

Assessing toss of periodontal support. It is apparent from this ali-too-hriefreview of the problems inherent in the loss of periodontal support that theclinical decision to declare a tooth hopeless is not an easy call The variablesof periodontai disease are numerous when faced with determining the long-range (another variable) prognosis of a given tooth. The interrelationship ofthe four major factors affecting prognosis is very obvious, Ali are essentiallya form of loss of attachment (loss of periodontal support) and a methcd ofmeasuring the potential for future maintenance and function.

Summary. The decision to place a tooth in the hopeless category is byno means a simple one. There is always the possibility of being wrong, thepossibility that this tooth may prove to be the exception and, against ailodds, survive as a functioning component of the masticatory apparatus.These are the decisions that make us dentists rather than technicians.

References1 Bender IB, Seltzer S, Roentgenographic and direct observation of experimental le-

sions in bone II J Am Dent Assoc 1961:62,708-716,2, Wilson TG, Kornmsn KS, Mellonig JT, Brunsvold MA, Treating aggressive fotms of

periodontal disease. In: Wilson TG, Kornman KS (eds). Fundamentals of Periodon-tics. Chicago- Quintessence, 'i996389-421

3, Grant DA, Stern IB, Listgatten IvlA (eds), Periodontics, ed 6. St Louis: Mosby,1988:573-591.

4, Hall WB. Deotsion Making in Periodontology, ed 3, St Louis: Mosby, 1998:70-75,5, American Association of Endodontists, Cracking the oraoked tooth code. Endodon-

tios. Colleagues fot Excellence 1997;FallA'Vinter:1-8,

For reprints contact; Dr John W. Harrison, Department of Restoratice Sciences,Baylor College of Dentistry, PO Box 660677, Dallas, Texas 75266-0677, Fax: 214-874-4544.

850 Volume 30, Number 12, 1999