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arly Management of Congenitally Missing Teethince Kokich, Jr.

Often children and adolescents are congenitally missing their maxillary lateral incisors ormandibular second premolars, and frequently it is the orthodontist who diagnoses theagenesis. In fact, early orthodontic intervention may eliminate some of the periodontal andrestorative problems that could arise in these patients as adults. An excellent implant sitecan be developed in the mixed dentition by extracting the maxillary primary lateral incisorand guiding the eruption of the permanent canine into the lateral incisor space. Occasion-ally, the mandibular primary second molar also may require extraction during early ado-lescence. This is due to ankylosis, which could become a significant periodontal concern,if not addressed early. When there is no permanent successor, an ankylosed primary molarmay need to be extracted so the alveolus will develop vertically as the patient grows.Therefore, the orthodontist plays a key role in monitoring eruption and growth of thesepatients at an early age. If this were done, the final result could be esthetic and predictable.This article will discuss the importance of early diagnosis and intervention in order topreserve various treatment options in the future.Semin Orthod 11:146–151 © 2005 Elsevier Inc. All rights reserved.

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axillary Lateral Incisorshe maxillary lateral incisor is one of the most commoncongenitally absent teeth. Two treatment options for pa-

ients with missing laterals are opening space or closingpace. Today implants have become the restoration of choice,hen the treatment plan is to open space. Since implants

annot be placed until facial growth is complete, monitoringruption, implant site development, and retention are impor-ant at an early age. This raises several interesting questions:

hat can be done in the mixed dentition to develop a futuremplant site? How much space is necessary? How will theingival architecture be affected in the area of the missingooth? These are concerns that the orthodontist must addresshen planning treatment for these patients in the mixedentition.

hat Can Be Done in the Mixed Dentitiono Develop a Future Implant Site?s orthodontists, we evaluate patients with missing teeth atn early age. This allows us to monitor and guide eruptionhrough selective primary tooth extraction. Frequently, these- to 9-year-old children have retained maxillary primary

ateral incisors. Evaluation of periapical or panoramic radio-

niversity of Washington, Seattle, WA.ddress correspondence to Vince Kokich, Jr, DMD, MSD, 1950 S. Cedar

Street, Tacoma, WA 98405. Phone: (253) 627-5688; Fax: (253) 272-

t6719; E-mail: vkokich2@u.washington.edu

46 1073-8746/05/$-see front matter © 2005 Elsevier Inc. All rights reserved.doi:10.1053/j.sodo.2005.04.008

raphs may reveal that the crown of the developing perma-ent canine is positioned apical to the root of the primaryanine. Is early orthodontic treatment necessary? If an im-lant restoration will replace the missing lateral incisor, theaciolingual thickness of the alveolus must be adequate. Thelveolar ridge thickness may be influenced by the eruption ofhe permanent canine. Therefore, the orthodontist shouldncourage the canine to erupt adjacent to the permanententral incisor (Fig 1A and B).1 This may involve selectivextraction of a retained primary lateral incisor. As the perma-ent canine erupts into the edentulous space, it establisheshe thickness of the alveolus. As the canine is moved distally,n increased buccolingual alveolar width is established (FigA and B).2 Occasionally the canine may not erupt adjacento the central incisor. When this occurs, a bone graft may beecessary to establish the appropriate ridge thickness to placen implant.

ow Much Space Is Necessary?he orthodontist plays a key role in determining and estab-

ishing space requirements for patients with missing maxil-ary lateral incisors. The question that is often asked is: How

uch space is necessary for missing lateral incisor restora-ions? There are three ways to determine the appropriatepace for these missing teeth. The first is the golden propor-ion.3 This method measures teeth by evaluating a smiling orrontal intraoral photograph in a two-dimensional view.ince the maxillary teeth are positioned in a curved arch, each

ooth should be 61.8% wider than the tooth distal to it (Fig

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Congenitally missing teeth 147

).4 For example, a photograph of a maxillary dental archith an 8-mm-wide central incisor crown should contain a

ateral incisor crown width of 5 mm.The second method to determine the appropriate restor-

igure 1 (A) Often the primary lateral incisor will be retained inatients with congenitally missing maxillary lateral incisors. (B) Theoal is often selective extraction of the retained primary canine toncourage eruption of the permanent canine into the missing lateralncisor position. This will ultimately develop the alveolar ridge formplant placement.

tive space is to use the contralateral lateral incisor.3 If this t

ooth has a normal width, it can often be used as a guide forhe orthodontist to establish ideal spacing for the missingateral incisor. Unfortunately, this method of space appropri-

igure 2 (A) As the permanent canine erupts adjacent to the centralncisor, its large buccolingual width begins to develop the alveolaridge in the edentulous area. (B) The canine is moved distally, leav-ng behind an adequate buccolingual width for implant placement.

igure 3 The “golden proportion” is a two-dimensional measure-ent of esthetics. It is applied dentally when viewing the arrange-ent of the maxillary anterior teeth in a frontal photograph. Each

ooth, beginning with the central incisor, should be 61.8% larger

han the tooth distal to it.

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148 V. Kokich Jr

tion is not appropriate for adolescents with missing or peg-haped contralateral lateral incisors. Therefore, a thirdethod of space appropriation is to conduct a Bolton analy-

is.5 Bolton first introduced his ratio in 1958 as a way toompare the mesiodistal widths of the dental arches to

igure 4 (A) The maxillary canine should be positioned in the em-rasure between the mandibular canine and first premolar. This willllow for proper canine disclusion. (B) The maxillary central inci-ors should be positioned in the appropriate overbite and inclina-ion to achieve ideal esthetics.

igure 5 As the canine is moved mesially in a nongrowing patient,

the papilla is left in its original position, mesial to the premolar.

chieve ideal occlusal relationships. His anterior measure-ent involves dividing the sum of the mesiodistal width of

he mandibular six anterior teeth by the sum of the mesiodis-al width of the maxillary six anterior teeth. This ratio ispproximately 0.786 and can be used to mathematically cal-ulate the width of the edentulous spaces for a patient who isongenitally missing one or both maxillary lateral incisors.

The most predictable guide for determining ideal spacings to construct a diagnostic wax setup. This simplifies treat-

ent for the orthodontist and restorative dentist. Fortunatelyost adolescents have healthy, nonrestored teeth and do not

xhibit significant wear. Therefore, the spacing will be deter-ined ultimately by the occlusion. The canines should belaced in a position that will achieve canine disclusion withhe central incisors in a position that will provide optimalsthetics (Fig 4A and B).3,7,8 The space that remains should bedeal for the lateral incisor restoration. This space is generally

to 7 mm.To select the appropriate restoration for the edentulous

pace, several diagnostic criteria should be evaluated. Thereatment of choice should be the least invasive option thatatisfies the esthetic and functional objectives. Single-toothmplants are often the most conservative restoration, because

igure 6 (A) In this adult patient, the canine was moved mesially,hus everting the sulcus distal to the canine. (B) This red, nonkera-inized, sulcular epithelium gradually keratinizes over time. How-ver, the position of the papilla does not change.

hey do not require tooth preparation. However, they should

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Congenitally missing teeth 149

ot be placed until facial growth is complete. Therefore,ong-term retention of these edentulous spaces may be nec-ssary. Fixed bridges are less conservative. These tooth-borneestorations include resin bonded, canine cantilever, and fulloverage bridges. Selection of the appropriate fixed bridgeepends on the position and condition of the abutment teeth.

ow Will the Gingival Architecturee Affected in the Edentulous Area?

magine a patient in the mixed dentition with missing lateralsnd a wide diastema between the permanent central incisors.he centrals could occupy over half of the natural lateral

ncisor position. When the centrals are moved mesially, andhe diastema is closed, there should be adequate alveolaridth for an implant. However, in an adult, this direction of

ooth movement will affect papilla heights on the distal of theentral incisors as the teeth are moved mesially to close theiastema (Fig 5). According to Atherton, the distal sulcus wille everted as the space is closed leaving the papilla behind.9

s the nonkeratinized gingiva is exposed, the tissue appearsed. Over time this tissue will keratinize, but the location ofhe papilla does not change (Fig 6A and B). In an adult this

Figure 7 (A) Before reducing the width of the primary moappropriate final dimensions. (B) After the mesial and dito 8.0 mm. This is allowed to heal for 2 to 3 weeks. (C) Winterproximally and occlusally to recreate an acceptableis then banded or bracketed and the residual space is cl

lar, lines can be drawn on the occlusal surface to delineate thestal surfaces are reduced, the overall width should measure 7.5hen the patient returns 2 to 3 weeks later, composite is bondedpremolar shape and occlusion. (D) The primary second molar

ould be an esthetic challenge for the periodontist and restor- t

igure 8 As a patient grows, the teeth continue to erupt to maintaincclusion. However, an ankylosed, primary molar will not erupt. Asresult, a significant marginal ridge discrepancy develops between

he ankylosed molar and the teeth adjacent to it. If the tooth is notxtracted early, the adjacent teeth can begin to tip over the crown of

he ankylosed molar, as can be seen in this picture.

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150 V. Kokich Jr

tive dentist when placing the implant and designing theestoration. Fortunately, in the mixed dentition as the child’sace continues to grow and the teeth erupt, the bone andingiva constantly change. As a result, the papillae adjacento the implant site are not affected permanently.

andibular Second Premolarshe mandibular second premolar is another common con-enitally missing tooth. An important factor in managinghese patients at an early age is space maintenance. Fre-uently the orthodontist diagnoses the agenesis on a pan-ramic radiograph. If the patient has no arch length defi-iency and will not require extractions to treat thealocclusion, it is important to maintain the primary molar

s long as possible. However, the mesiodistal width of therimary second molar creates a mandibular tooth-size excesshat makes it difficult for the orthodontist to achieve idealnterdigitation of the posterior teeth. How can the orthodon-ist achieve an acceptable posterior occlusion and still retainhe primary molar for long-term space maintenance? What ifhe primary molar becomes ankylosed? How should the orth-dontist evaluate whether or not the ankylosed tooth re-uires extraction? These are questions that the orthodontistust answer during dental development to preserve various

reatment options in the future.

ow Can the Orthodontist Achieve ancceptable Posterior Occlusionnd Use the Primary Second Molars a Long-Term Space Maintainer?

t is advantageous to maintain the primary second molar asong as possible to maintain the alveolar bone both verticallynd buccolingually. However, it is often difficult for the orth-dontist to achieve ideal posterior interdigitation of the oc-lusion, due to the width of the primary molar.2 A normalrimary second molar is about 9.5 mm wide. Therefore, itay be beneficial to reduce the mesiodistal width so that it

pproaches the width of a second premolar 7.5 to 8.0m.1,3,10 When determining the extent of tooth reduction,

he clinician should evaluate crown width and root diver-ence on a periapical radiograph. The crown of a primaryolar converges significantly toward the cervical region and

llows the orthodontist to reduce the crown width by 1.5 to.0 mm. However, the extent of reduction may be limited, ifhe roots diverge significantly.

Once the appropriate amount of reduction has been cal-ulated, this information can be drawn on the occlusal sur-ace. A fissure bur in a high speed handpiece is the mostfficient way to achieve adequate reduction. Typically pa-ients do not require local anesthesia, because the pulp hasndergone significant constriction by age 14 to 15, when therocedure is usually performed.2 After the tooth reductionas been completed, light-cured composite may be placed

nterproximally to cover the exposed dentin. It is often nec-ssary to bond composite on the occlusal surface to establish

dequate crown height and occlusal contact. Then the orth- t

dontist can bracket the primary molar, close the residualpace, and finish the occlusion. The result is an esthetic,unctional restoration that will maintain space and alveolarone support before implant placement (Fig 7A-D).2

hen Should an Ankylosedrimary Molar Be Extracted?ortunately primary molar ankylosis is a relatively uncom-on occurrence, which is often diagnosed during the mixedentition. As the face grows and the mandibular ramus

engthens, teeth must erupt to remain in occlusion. An anky-osed tooth cannot erupt. As the adjacent teeth continue torupt, an ankylosed primary molar appears to submerge far-her below the level of the occlusal plane (Fig 8).11,12 Thisften results in a vertical bony defect between the primaryolar and the adjacent permanent teeth, which ultimatelyay affect implant placement.It is easy to misdiagnose ankylosis of a primary molar.

fter all, the crown height of the primary molar is shorterhan the adjacent permanent first molar. Therefore, a mar-inal ridge discrepancy between these teeth does not indicatehat the primary molar is ankylosed. Methods of detecting

igure 9 (A) A developing vertical, bony defect is becoming visibleadiographically as seen on this bitewing radiograph. (B) This youngatient exhibits a severe vertical, bony defect. The ankylosed, pri-ary second molar requires extraction in order for the alveolus to

ontinue developing vertically as the patient grows and the adjacent

eeth erupt.

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Congenitally missing teeth 151

nkylosis, such as tapping the tooth to detect a difference inound, are generally not reliable. The best method of detect-ng ankylosis is evaluation of interproximal bone levels on aitewing radiograph. When the bone level is flat, adjacenteeth are erupting at the same rate. However, if a vertical boneefect is visible radiographically, then the primary tooth isnkylosed and may require extraction to avoid a significantertical ridge defect (Fig 9A and B). The extraction can be aifficult procedure, which often requires a flap and boneemoval. The result may be a narrow alveolar ridge that re-uires bone grafting before implant placement.Growth potential and tooth position determine whether or

ot an ankylosed primary second molar should be extracted.patient with significant growth potential, such as a 15-year-

ld male, may require extraction of an ankylosed primaryolar. This allows the alveolar ridge to develop occlusally as

he adjacent teeth continue to erupt.3,13 Donnelly andwoope demonstrated that as the periosteum is stretchedver an edentulous ridge, osteoblastic activity is stimulated toay down bone and promote alveolar ridge development.14

owever, extraction of an ankylosed primary second molaray not be necessary in a 15-year-old female with little or no

rowth potential. If the primary molar is in an acceptableosition, it can be maintained, but likely will require inter-roximal reduction and restoration of the occlusal surface tochieve an optimal occlusion.

onclusionsrthodontists frequently encounter patients with congeni-

ally missing teeth. The most common are maxillary lateralncisors and mandibular second premolars. Treatment deci-ions must be made based on eruption pattern, growth po-ential, tooth position, and tooth health. If the patient is miss-ng one or both maxillary lateral incisors, guided eruption

nd ridge development are critical. Early diagnosis and treat-

ent of ankylosed primary second molars also may be im-ortant for the periodontal and restorative treatment of thedolescent patient. Therefore, monitoring these patients inhe mixed dentition is essential to preserve various treatmentptions in the future.

eferences1. Biggerstaff RH: The orthodontic management of congenitally absent

maxillary lateral incisors and second premolars: a case report. Am JOrthod Dentofacial Orthop 102:537-545, 1992

2. Kokich VG: Managing orthodontic—restorative treatment for the adoles-cent patient, in McNamara JA, Brudon WL (eds): Orthodontics and Dento-facial Orthopedics. Ann Arbor, MI, Needham Press, 2001, pp 423-452

3. Spear F, Mathews D, Kokich VG: Interdisciplinary management ofsingle-tooth implants. Semin Orthod 3:45-72, 1997

4. Lombardi RE: The principles of visual perception and their clinicalapplication to denture esthetics. J Prosthet Dent 29:358-382, 1973

5. Freeman JE, et al: Frequency of Bolton tooth size discrepancies amongorthodontic patients. Am J Orthod 110:24-27, 1996

6. Bolton WA: Disharmony in tooth size and its relation to the analysis andtreatment of malocclusion. Am J Orthod 28:113-130, 1958

7. McNeill RW, Joondeph DR: Congenitally absent maxillary lateral inci-sors: treatment planning considerations. Angle Orthod 43:24-29, 1973

8. Nordquist GG, McNeill RW: Orthodontic vs. restorative treatment ofthe congenitally absent lateral incisor—long term periodontal and oc-clusal evaluation. J Periodontol 46:139-143, 1975

9. Atherton JD: The gingival response to othodontic tooth movement.Am J Orthod Dentofacial Orthop 58:179-186, 1970

0. Sabri R: Management of congenitally missing second premolars withorthodontics and single tooth implants. Am J Orthod Dentofacial Or-thop 125:634-642, 2004

1. Kurol J, Thilander B: Infroaocclusion of primary molars with aplasia ofthe permanent successor. a longitudinal study. Angle Orthod 54:283-294, 1984

2. Bennett J: The long term survival of lower second primary molars in sub-jects with agenesis of the premolars. Eur J Orthod 22:245-255

3. Ostler MS, Kokich VG: Alveolar ridge changes in patients congenitallymissing mandibular second premolars. J Prosthet Dent 71:144-149, 2000

4. Donnelly MW, Swoope CC: Periosteal tension in the stimulation ofbone growth in the mandible. Master’s thesis. Seattle, WA, University of

Washington, 1973