81

MAY 2011 • DENTALCETODAY.COM

AESTHETICSdentalCEtoday.com Test 137

Congenitally missing maxillary later-al incisors are the second most com-mon dental agenesis, exceeded only

by third molars.1,2 Hypodontia, the absenceof one or a few teeth, arises from a distur-bance early in the tooth formation processduring initiation or proliferation of thetooth bud. As a rule, if a tooth is absent, themost distal tooth of a type will be affected.Tooth malformations result from later dis-turbances during the differentiation stagesof dental development, and these are mostcommonly manifested as size variations.3Other dental anomalies that are frequentlyassociated with congenitally missing teethinclude microdontia, delayed dental devel-opment, and certain discrete ectopic erup-tion of the tooth.4,5 There is a significantassociation between the agenesis of maxil-lary lateral incisors and the agenesis of oth -er permanent teeth, as well as an in creasedoccurrence of microdontia of the maxillarylateral incisors, palatal displacement ofcanines, and distal angulation of mandibu-lar second premolars.5,6

The congenital absence of one or moremaxillary lateral incisors introduces apotential imbalance in the maxillary andmandibular dental arch length in the per-manent dentition. Treatment planning forcongenitally missing maxillary lateral inci-sors often presents a difficult task for prac-titioners because aesthetic as well as func-tional treatment results are desired. There -fore, to produce the most predictable aes-thetic results, it is important to choose atreatment that will best focus on the initialdiagnosis.7 To provide aesthetic anteriortooth shape and correct the problem ofmissing teeth, patients must be informed oftheir total dental needs, not just those asso-ciated with a limited specialty. That is,patients need to be offered a total treatmentapproach from an interdisciplinary dentalspecialty team that will integrate and coor-dinate treatment to maximize function,aesthetics, and oral health.8

This article discusses factors in deter-mining whether to close an open space orto open enough space for a prosthetic treat-ment for congenitally missing maxillary

lateral incisors. Further, the importance ofa total treatment approach using an inter-disciplinary dental specialty team to maxi-mize function, aesthetics, and oral health isdiscussed.

TREATMENT SELECTIONThe treatment method selected for congeni-tally missing maxillary lateral incisorsshould provide treatment results acceptableto both facial and dental aesthetics. A num-ber of factors need to be considered whendeciding whether to close the space left by amissing maxillary lateral incisor or to openspace in preparation for a prosthetic tooth.These factors include the posterior occlusalrelationships, the position of the canines at

the time of diagnosis, the shape and color ofthe canines, whether or not extractionswould be necessary, and the potential forreferring and coordinating prosthodontictreatment with orthodontic therapy.8,9

In most cases, the existence of a skeletalmalocclusion serves as the primary criteri-on in the treatment selection for congenital-ly missing maxillary lateral incisors.10Apart from this, selecting an appropriatetreatment option for each patient dependson the specific space requirements, tooth-size relationship, and size and shape of thecanines. The ideal treatment is the mostconservative approach that minimizes theneed for tooth reduction and is the leastinvasive method of satisfying the patient’saesthetic and functional requirements. Incontemporary dentistry, there are 3 treat-ment options for replacing missing lateralincisors: a canine substitution, a tooth-sup-ported prosthesis, or a single-tooth implant.

Even though an orthodontist may posi-tion a canine in the most aesthetic and func-tional location, the prosthodontist often stillneeds to place a porcelain laminate or fullcrown to create normal lateral incisor shapeand color because the size and shape of max-illary canines is usually significantly differ-ent than that of maxillary lateral incisors.7Orthodontic space opening and lateral inci-

Figure 1. If the patient has a high smile-line, thegingival levels will be more visible with more prominent canine root eminence, which causesirregularities in maxillary gingival contours and anunaesthetic frontal view.

Figure 2. (a) Orthodontic extrusion of the maxillary canines. (b) The maxillary canine gingival lines are sim-ilar to the lateral incisors. (c) Equilibration of the canine cusp tips is completed. (d) Composite restorationof the mesioincisal areas.

Congenitally Missing MaxillaryLateral Incisors: Treatment

Jae Hyun Park,DMD, MSD,MS, PhD

Dong-Ae Kim,DDS, MS, PhD

Kiyoshi Tai,DDS

a b

c d

cece

FOR EDUCATIO

NAL AND/O

R PERSONAL

USE ONLY

sor replacement, the other treatmentoptions, are sometimes preferred. Asthe permanent canine is moved distal-ly to create space for a lateral incisorprosthesis or implant, an alveolar ridgeis created. The clinician should alignthe maxillary central incisor midlinewith the upper lip and face when cre-ating mesiodistal space for lateral inci-sor restoration. Radio graphs should betaken after the alignment is completeto confirm the ridge and root positionsof the central incisors and the canines.For implant or restorative cases, theroot position should be evaluated bythe orthodontist, the surgeon, and theprosthodontist.7-9

CANINE SUBSTITUTIONThere are several patient-specific den -tofacial criteria that must be evaluatedbefore selecting canine substitutiontreatment for replacing a missing max-illary lateral incisor. These in clude thepresence of malocclusion and amountof crowding, facial profile, canineshape and color, lip level, and gingivalcontours.11,12 A fixed prosthesis or sin-gle-tooth implant should be consid-ered if the patient fails to meet any ofthese criteria. Pa tients with a missingpermanent incisor and a coexistentmalocclusion must therefore be man-aged with an overall treatment plan inwhich aesthetics and long-term dentalhealth are of paramount impor-tance.7,11,13

MalocclusionThe presence of malocclusion is a pri-mary criterion for making canine sub-stitution the treatment choice for con-genitally missing lateral incisors. Thefirst type of malocclusion is an AngleClass II malocclusion with no or slightcrowding in the mandibular arch.With Class II malocclusion cases, themolar relationship remains Class II,and a first premolar is located in thetraditional canine position and acts asa canine. By closing space, anterioroverjet is corrected to achieve optimalinterincisal relationships. The nextalternative is an Angle Class I maloc-clusion with severe crowding, whichrequires extraction in the mandibulararch. In these 2 malocclusions, thefinal occlusion should be designed sothat the lateral excursive movementsare in an anterior group function.14Evaluation of the anterior tooth-sizerelationship is important when substi-tuting canines for lateral incisors.Canine substitution can create exces-sive size of maxillary anterior teeth,and in order to achieve a normal over-bite and overjet relationship, thisexcessive size must often be reduced.11

Completion of a diagnostic wax-up is avaluable tool in the treatment selec-tion process to identify tooth surfaces,which will require functional and aes-thetic changes to facilitate desiredocclusal relationships.

ProfilePatients with a balanced, relativelystraight profile are ideal candidatesfor canine substitution of congenital-ly missing lateral incisors. Patientswith a mildly convex profile may beacceptable, too, but patients having amoderately convex profile with a re -trusive mandible and a deficient chincontour may not be appropriate can-didates for this treatment. It would bemore appropriate to choose a treat-ment option that addresses not onlythe dental malocclusion but the facialprofile as well.7,15 With skeletal ClassIII profiles, it is often wiser to choosespace opening for a single-toothimplant or tooth-supported restora-tion because space closing may aggra-vate the Class III facial profile.

Canine Shape and ColorThe shape and color of the canine arenot the primary criteria for selecting

canine substitution as a treatment forcongenitally missing maxillary lateralincisors, but they are important factorsif the canine substitution is to be suc-cessful and aesthetic. The canine is amuch larger tooth than the lateral inci-sor it replaces, with a wider crown anda more convex labial surface. As such,canines usually require a significantamount of reduction in order toachieve acceptable occlusion and aes-thetics. However, removal of a consid-erable amount of enamel with the goalof establishing proper surface contoursmay result in the underlying dentinshowing through the thin enamel,thereby decreasing the aesthetics.7 In acanine with a greater degree of labialconvexity, dentin exposure can occur,leading to the need for prostheticreplacement. Depending on theamount of incisal edge wear of thecanine, it may be necessary to restorethe mesioincisal and distoincisal edgesto create normal lateral contours.12 Asignificant amount of incisal and lin-gual reduction is generally required tovertically position a canine in theappropriate lateral incisor location.7,8

The color of the substituted ca -nine should also be examined andshould be approximately the same asthe central incisor. However, caninesare usually darker than central inci-sors, therefore the most conservativeway to correct the color difference isto individually bleach them. If thisfails to approximate the desired color,a laminate may be indicated.

Lip LevelThe amount of gingival exposure dur-ing a smile may cause aesthetic con-cerns after canine substitution in somecases. Gingival levels will be more visi-ble, and canine root eminence will bemore prominent, in patients with ex -cessive gingiva-to-lip distance whensmiling. This may be due to a verticalmaxillary excess or a lip incompetency.Occasionally, a gingivectomy may needto be performed to properly scallop thegingival margins.6,7 In patients withhigh smile-lines, a prominent canineroot eminence may also be unaesthetic(Figure 1).16,17

Gingival ContoursMaxillary canines frequently exhibithigh gingival contours, which pro-duce unaesthetic smile-lines. Thiscauses irregularities in the maxillarygingival contour. After the maxillarycanines have been extruded, a res -torative touch-up is often needed torecreate an ideal lateral incisor con-tour.7

Since maxillary canines havemore triangular contours than inci-sors, the contact point between maxil-lary central incisors might show opengingival embrasures. This causes aes-thetic problems, and gingival inflam-mation is more frequent due to plaque

82

DENTALCETODAY.COM • MAY 2011

AESTHETICS

Figure 3. (a) Recontouring (red area) of themaxillary canine to simulate a lateral incisor.(b) Enamel recontouring (blue area) of the maxillary first premolar for canine substitution.

continued on page 84

a b

Figure 4. (a) Recontouring (red area) of theprominent labial ridge of a canine beforebonding a bracket. During the finishing stage,the lingual surface is reduced (blue area) toestablish a balanced occlusion. (b) To makethe canine appear less curved and more likea lateral incisor, the bracket is positionedmore distally.

a b

Figure 5. Pretreatment intraoral photographs and a panoramic radiograph showing missing maxillary lateral incisors with unaesthetic gingival contours and deep overbite.

FOR EDUCATIO

NAL AND/O

R PERSONAL

USE ONLY

accumulation in these embrasures.18Open gingival embrasures are influ-enced by the direction of tooth move-ment and by the labiolingual thick-ness of the supporting bone and softtissue after orthodontic treatment. Inorder to eliminate or reduce open gin-gival embrasures, it is recommendedthat the root movement of substitut-ed maxillary canines be adequate toconverge roots after space closure. Inaddition, restorative reshaping of thecrown may be indicated.

Orthodontic Treatment for Space Closing

The decision whether to close space andsubstitute maxillary canines for lateralincisors or to open space for restorationof missing teeth will de pend on severalfactors including the patient’s age, atti-tude toward orthodontic treatment,treatment ex pec tations, and financialobligations.19,20 To substitute caninesfor maxillary lateral incisors, spaceshould be created either by extractingdeciduous canines or by allowing per-manent canines to move mesiallyadjacent to the maxillary central inci-sors. Lateral brackets may be placed oncanines when treating patients withcanine substitution, positioned ac -cording to gingival margin heightrather than on the cusp tip of the sub-stituted canines. The brackets on thesubstituted canines should be placedat a distance from the gingival marginsuch that they will erupt these teeth tothe appropriate lateral incisor verticalheight. The canine tips may then berecontoured to mimic lateral incisors,thus leveling the gingival margin. Byplacing canines in the correct verticalheight, aesthetic gingival contourscan also be achieved. The gingival

mar gin of the substituted canineshould be positioned slightly incisal tothe central incisor gingival margin.This helps camouflage the substitutedcanine (Figure 2).7

In the finishing stage, the ortho-dontist must reduce the width of thecanine interproximally to achieveoptimal aesthetics and a normal over-jet relationship. Interproximal as wellas occlusal canine tips need to be con-toured to imitate lateral incisors.Adjunctive prosthetic treatment isoften necessary to create ideal lateralincisor shape and color. When thefinal stages of orthodontics are com-plete, verify that the space closure isproper and that angulation and me -siodistal positioning of incisors areappropriate. Interdisciplinary treat-ment is often necessary to achieveoptimal final aesthetics and may in -volve additional crown recontouring,composite restorations, or gingivecto-my (Figures 3 and 4).8

Patients treated with orthodonticspace closure were generally more sat-isfied with the appearance of theirteeth than patients treated with pros-thetic replacements. Although no sig-nificant differences in the prevalenceof signs and symptoms of temporo-mandibular joint disorders were foundbetween the 2 treatment mo dalities,21patients treated with prosthetic re -placement experienced im paired peri-odontal health from plaque accumula-tion and gingivitis.18

SPACE OPENING FOR PROSTHETICREPLACEMENT OF MAXILLARY

LATERAL INCISORSIn cases with Class I skeletal relation-ships where there is neither mandibu-lar arch crowding nor dentoalveolar

protrusions, orthodontic space open-ing treatment and prosthetic lateralincisor replacement is preferred totreatment by space closing for main-taining posterior occlusion. To re -place a congenitally missing lateralincisor with a prosthetic restoration,specific criteria must be evaluated ona patient-by-patient basis by an inter-disciplinary team of prosthodontistand orthodontist to achieve the mostpredictable treatment results. Thetreatment of choice should be theleast invasive option that satisfies theexpected aesthetic and functionalobjectives for the individual patient.

In creating the proper mesiodistalspace for lateral incisor restoration, theclinician should position the centralincisors with respect to the midpoint ofthe cupid’s bow on the philtrum of theupper lip and upper face, and havemaxillary and man dibular midlinescoincide.8 Aligning the maxillary mid-line to the upper lip and face is moreimportant. Radio graphs should betaken after the alignment is completedto confirm the ridge and root positionsof the central incisors and canines. Forimplant or prosthetic cases, the rootposition must be evaluated by an ortho-dontist, surgeon, and prosthodontist.7-9

Determination of Appropriate Spacing

The first step in opening space for atooth-supported prosthesis or single-tooth implant is to determine howmuch space is necessary for the miss-ing lateral incisor replacement. Thereare several methods for doing this. Thefirst method is called the ‘‘golden pro-portion.’’22 The perceived width ofeach anterior tooth should have a ratioof 1:1.618 to the tooth adjacent to it.

The second method is to use thecontralateral lateral incisor as a refer-ence,23 but this method is not suitedfor patients with missing or peg-shaped contralateral incisors.

The third method is to conduct aBolton analysis.24 It involves dividingthe sum of the mesiodistal widths ofthe 6 anterior mandibular teeth by thesum of the mesiodistal widths of the 6anterior maxillary teeth. The anteriorBolton ratio should be approximately77.2.24,25 The Bolton analysis is aquick and reliable way to determinethe appropriate space necessary forpatients with congenitally missinglateral incisors.

The fourth and most predictableguide for determining the ideal re -placement space is to construct a diag-nostic wax-up. Generally, the max -illary lateral incisor width rangesfrom 5 to 7 mm.

84

DENTALCETODAY.COM • MAY 2011

AESTHETICS

Figure 6. Intraoral treatment progressviews.

Figure 7. Post-treatment intraoral photographs and a panoramic radiograph with missing maxillary lateral incisors. The maxillary left lateralincisor space was closed, and the maxillary right lateral space was opened. The gingival contours and deep overbite have been improved.

Congenitally Missing Maxillary...continued from page 82

FOR EDUCATIO

NAL AND/O

R PERSONAL

USE ONLY

85

MAY 2011 • DENTALCETODAY.COM

Three Types of Tooth-SupportedProstheses

There are 3 basic types of tooth-sup-ported prostheses available today.They are a resin-bonded fixed bridge, acantilevered fixed bridge, and a con-ventional full-crown fixed bridge. Theprimary consideration among thesetreatment options is conservation oftooth structure. Ideally, the treatmentof choice should be the least invasiveoption that satisfies both aesthetic andfunctional objectives for the patient.

Resin-bonded Fixed Bridge—This isthe most conservative method forreplacing a missing lateral incisorwith a tooth-supported prosthesis.The success rate with this type of pros-thesis varies widely from 46% over 11months to 90% over 11 years, with themost common form of failure beingdebonding.26 The specific criteria for a

successful treatment using a resin-bonded fixed bridge include the posi-tion, mobility, thickness, and translu-cency of the abutment teeth as well asthe overall occlusion.

Resin-bonded fixed bridges placedin a deep overbite relationship havebeen shown to have a higher incidenceof failure.27 The ideal anterior relation-ship for a resin-bonded fixed bridge is ashallow overbite. Another concernregarding tooth position is inclinationof the abutment teeth. Abutment teethwith increased inclination are moreprone to debonding. The mobility ofthe abutment teeth is a contraindica-tion for a resin-bonded fixed bridge. Afinal area of concern regarding place-ment of a resin-bonded fixed bridge isocclusal parafunction, which placestoo much stress on the pontic and sub-sequently results in prosthesis failure.Abutment teeth that are immobile,moderately thick, and have translu-cency mainly localized in the incisalone third are ideal candidates for aresin-bonded fixed bridge. A shallowoverbite allows maximum surface areafor bonding retainers with little or notooth preparation.27,28

Cantilever Bridge—The secondmost conservative tooth-supportedprothesis designed to replace a con-genitally missing lateral incisor is acantilevered fixed bridge. The successof this type of restoration is notdependent on the amount of proclina-tion or mobility of the abutment teeth.Intracoronal pins provide retentionand resistance for a cantilevered

bridge; therefore the size of the pulpand its location within the tooth mustbe evaluated prior to the selection ofthis type of restoration. The long-termsuccess of the cantilevered fixedbridge depends on management of theeffects of occlusion on the pontic(s).29Heavy occlusal forces applied on thepontics cause early failures.

Conventional Full-Coverage FixedBridge—The least conservative butsturdiest of all tooth-supported prothe-ses is a conventional full-coverage fixedbridge. A conventional fixed bridgeexerts control over the occlusion andocclusal forces. Before a full-coveragefixed bridge is placed, the alignment ofthe anticipated abutment teeth along acommon pathway must be verified.From the frontal view, the long axis ofthe central incisor and the labial surfaceof the canine should be parallel. This

allows the prosthodontist to achievethe proper ‘‘line of draw’’ when prepar-ing these teeth. Also, from a lateral per-spective, the long axis of the canine andthe labial surface of the central incisormust be parallel for proper tooth prepa-ration. The orthodontist must knowhow to align these teeth according tothe specific restorative requirements forthe chosen prosthesis. Another consid-eration is the faciolingual position ofthe abutment teeth as it relates topalatal tooth preparation and theamount of preparation. The orthodon-tist can help to reduce the need for toothpreparation by leaving an overjet ofapproximately 0.5 to 0.75 mm.28

Each of the above prosthetic meth-ods can be used with a high degree ofsuccess if used in the appropriate situ-ation. Interdisciplinary managementof patients with congenitally missinglateral incisors often plays a vital rolein the success of the treatment. Thecombined efforts of the prosthodon-tist and orthodontist can produce pre-dictable and aesthetic treatment re -sults for congenitally missing lateralincisors (Figures 5 to 9).

SINGLE-TOOTH IMPLANT Today, the single-tooth implant hasbecome one of the most common treat-ment alternatives for the replacementof missing teeth. As with treatmentthat uses fixed bridges, an interdiscipli-nary approach is necessary to providethe most predictable treatment resultswhen single-tooth im plants are insert-ed to replace congenitally missing lat-eral incisors. Osseo integration enableslong-term stability of a prothesis sup-ported by a single-tooth implant.29-31The most important advantage ofusing implants to replace missing lat-eral incisors is that they leave proximalteeth untouched. Implants have be -come the restoration of choice for mostpatients when the treatment option isto open space. For implant treatmentto be successful, there must be an ade-quate intercoronal and interradicularspace opening and root paralleling ofthe adjacent teeth, including the apicalareas, and the abutment teeth must becompletely stabilized.32

When maxillary lateral incisorsare congenitally missing, permanentcanines frequently erupt mesial totheir normal positions. After the ca -nine has erupted, it can be moved dis-tally into its normal position by

AESTHETICS

Figure 8. Post-treatment intraoral photo-graphs after restoring 4 anterior teeth.

Figure 9. Post-retention intraoral photographs and a panoramic radiograph after 2 years of orthodontic treatment.

There are 3 basic types of tooth-supported prostheses available today.

FOR EDUCATIO

NAL AND/O

R PERSONAL

USE ONLY

86

orthodontic treatment. By moving thetooth distally, bone is laid down,forming an alveolar ridge with ade-quate buccolingual width to allowproper implant placement. Since im -plants are most suitable as a res -torative option for adults after facialgrowth is complete, the need to main-tain alveolar bone for several yearsuntil growth has ceased presentsanother challenge.32,33

SUMMARYThe 2 major treatment approaches forcongenitally missing maxillary lateralincisors are space closure via orthodon-tic therapy, or space opening to allowprosthodontic replacements eitherwith a fixed prosthesis or single-tooth

implant. Both of these treatmentapproaches can potentially compro-mise aesthetics, periodontal health, andfunction. It is essential for an interdisci-plinary dental specialty team to estab-lish realistic treatment objectives, com-municate the sequence of treatment,interact during treatment, evaluate den-tal and gingival aesthetics, and positionteeth to permit proper prosthetic treat-ment. If this interdisciplinary approachis used, the aesthetics and long-termdental health of the patient followingtreatment will be greatly enhanced.�

References1. Polder BJ, Van’t Hof MA, Van der Linden FP, et al.A meta-analysis of the prevalence of dental age-nesis of permanent teeth. Community Dent OralEpidemiol. 2004;32:217-226.

2. Graber LW. Congenital absence of teeth: a review

with emphasis on inheritance patterns. J AmDent Assoc. 1978;96:266-275.

3. Proffit WR, Fields HW Jr, Sarver DM. Con -temporary Orthodontics. 4th ed. St. Louis, MO:Mosby; 2007:135-141.

4. Sacerdoti R, Baccetti T. Dentoskeletal featuresassociated with unilateral or bilateral palatal dis-placement of maxillary canines. Angle Orthod.2004;74:725-732.

5. Peck S, Peck L, Kataja M. Concomitant occur-rence of canine malposition and tooth agenesis:evidence of orofacial genetic fields. Am J OrthodDentofacial Orthop. 2002;122:657-660.

6. Garib DG, Alencar BM, Lauris JR, et al. Agenesisof maxillary lateral incisors and associated den-tal anomalies. Am J Orthod Dentofacial Orthop.2010;137:732.e1-732e6.

7. Kokich VO Jr, Kinzer GA. Managing congenitallymissing lateral incisors. Part I: Canine substitu-tion. J Esthet Restor Dent. 2005;17:5-10.

8. Park JH, Okadakage S, Sato Y, et al. Orthodontictreatment of a congenitally missing maxillary later-al incisor. J Esthet Restor Dent. 2010;22:297-312.

9. Miller WB, McLendon WJ, Hines FB III. Two treat-ment approaches for missing or peg-shaped maxil-lary lateral incisors: a case study on identical twins.Am J Orthod Dentofacial Orthop. 1987;92:249-256.

10. McNeill RW, Joondeph DR. Congenitally absentmaxillary lateral incisors: treatment planning con-

siderations. Angle Orthod. 1973;43:24-29.

11. Kokich VG. Managing ortho-dontic restorative treatmentfor the adolescent patient.In: McNamara JA Jr, BrudonWL, Kokich VG, eds. Or -tho dontics and Dento facialOrthopedics. Ann Arbor,MI: Needham Press;2001:1-30.

12. Zachrisson BU. Improvingorthodontic results incases with maxillary inci-sors missing. Am J Orthod.1978;73:274-289.

13. Kokich VO Jr. Congenitallymissing teeth: orthodonticmanagement in the ado-lescent patient. Am JOrthod Dentofacial Orthop.2002;121:594-595.

14. Tuverson DL. Orthodontictreatment using canines inplace of missing maxillarylateral incisors. Am JOrthod. 1970;58:109-127.

15. Carlson H. Suggested treat-ment for missing lateralincisor cases. Angle Orthod.1952;22:205-216.

16. Henns RJ. The canine emi-nence. Angle Orthod.1974;44:326-328.

17. Senty EL. The maxillarycuspid and missing lateralincisors: esthetics andocclusion. Angle Orthod.1976;46:365-371.

18. Robertsson S, Mohlin B.The congenitally missingupper lateral incisor. A retro-spective study of orthodon-tic space closure versusrestorative treatment. Eur JOrthod. 2000; 22:697-710.

19. Armbruster PC, GardinerDM, Whitley JB Jr, et al. Thecongenitally missing maxil-lary lateral incisor. Part 2:assessing dentists’ prefer-ences for treatment. World JOrthod. 2005;6:376-381.

20. Czochrowska EM, SkaareAB, Stenvik A, et al. Out -come of orthodontic spaceclosure with a missingmaxillary central incisor.Am J Orthod DentofacialOrthop. 2003;123:597-603.

21. Nordquist GG, McNeill RW.Orthodontics vs. restora-tive treatment of the con-genitally absent lateralincisor—long term peri-odontal and occlusal eval-uation. J Periodontol.1975;46:139-143.

22. Spear FM, Mathews DM,Kokich VG. Inter dis cipl i -nary management of sin-gle-tooth im plants. SeminOrthod. 1997;3:45-72.

23.Lombardi RE. The princi-ples of visual perception

and their clinical application to denture esthet-ics. J Prosthet Dent. 1973;29:358-382.

24.Freeman JE, Maskeroni AJ, Lorton L. Frequency ofBolton tooth-size discrepancies among orthodon-tic patients. Am J Orthod Dentofacial Orthop.1996;110:24-27.

25.Bolton WA. Disharmony in tooth size and its rela-tion to the analysis and treatment of malocclu-sion. Am J Orthod Dentofacial Orthop.1958;28:113-130.

26.Pröbster B, Henrich GM. 11-year follow-up studyof resin-bonded fixed partial dentures. Int JProsthodont. 1997;10:259-268.

27.Creugers NH, Käyser AF, Van’t Hof MA. A seven-and-a-half-year survival study of resin-bondedbridges. J Dent Res. 1992;71:1822-1825.

28.Kinzer GA, Kokich VO Jr. Managing congenitallymissing lateral incisors. Part II: tooth-supportedrestorations. J Esthet Restor Dent. 2005;17:76-84.

29.Decock V, De Nayer K, De Boever JA, et al. 18-year longitudinal study of cantilevered fixedrestorations. Int J Prosthodont. 1996;9:331-340.

30.Noack N, Willer J, Hoffmann J. Long-term resultsafter placement of dental implants: longitudinalstudy of 1,964 implants over 16 years. Int J OralMaxillofac Implants. 1999;14:748-755.

31.Zuccati G. Orthodontics and implant therapy toreplace a congenitally missing lateral incisor. JClin Orthod. 2004;38:563-567.

32.Turpin DL. Treatment of missing lateral incisors.Am J Orthod Dentofacial Orthop. 2004;125:129.

33.Kinzer GA, Kokich VO Jr. Managing congenitallymissing lateral incisors. Part III: single-toothimplants. J Esthet Restor Dent. 2005;17:202-210.

Dr. Park is a board certified orthodontist. Whileat New York University College of Dentistry(NYUCD), he received the Dean’s Award, theMaster of Science Resident Research Award,and the Post Graduate Resident ResearchAward. NYU submitted Dr. Park’s research for apatent. He also worked as an orthodonticteaching Fellow and member of the undergrad-uate clinical orthodontic faculty. He was select-ed as the NYUCD orthodontic resident repre-sentative to participate in the Ortho donticResident Scholars Program during the 2006American Association of Ortho dontists (AAO)session in Las Vegas and won first place, sci-entific section, in the orthodontic residentscholars program, competing with 47 nation-wide orthodontic resident representatives. Heis currently working as an associate professorand chair of the Postgraduate OrthodonticProgram at Arizona School of Dentistry and OralHealth and as an international scholar for theGraduate School of Dentistry at Kyung HeeUniversity in Seoul, Korea. The AAO recentlyappointed him to be the recipient of the AAOAcademy of Aca demic Leadership SponsorshipProgram Award for 2010. He can be reached at(480) 286-0455 or at jpark@atsu.edu.

Dr. Kim is an international visiting scholar,Postgraduate Orthodontic Program, ArizonaSchool of Dentistry and Oral Health, AT Still Uni -versity, Mesa, Ariz. She is also a clinical assistantprofessor, college of dentistry, Dankook Uni versityin Korea. She works as a concurrent professor inthe department of dental hygiene at PohangCollege in Korea. She is a Fellow of the WorldFederation of Orthodontists and an active mem-ber of the European Society of Lingual Ortho -dontics as well as an accredited orthodontist withthe Korean Association of Ortho dontists. She canbe reached via e-mail at kda2885@hanmail.net.

Dr. Tai graduated from the Dental School ofTokushima University in Japan. He is a visitingadjunct assistant professor, Postgraduate Ortho -dontic Program, Arizona School of Dentistry andOral Health, AT Still University, Mesa, Ariz. He isalso adjunct faculty at the Graduate School ofDentistry at Kyung Hee University in Seoul, Ko -rea. He is currently enrolled in the PhD program,Okayama department of oral and maxillofacialreconstructive surgery, Okayama UniversityGraduate School of Medicine, Dentistry andPharmaceutical Sciences, in Japan. He has lec-tured internationally on orthodontics. He can bereached at ktai@tai-ortho.com.

Disclosure: The authors report no disclosures.

AESTHETICS

FOR EDUCATIO

NAL AND/O

R PERSONAL

USE ONLY