canine substitution imp

Managing patients with congeni-tally missing maxillary lateral

incisors raises several important issues:Amount of space? Patient age? Type ofmalocclusion? Condition of the adja-cent teeth? There are three treatmentoptions that exist for replacing missinglateral incisors. These options include:canine substitution, a tooth-supportedrestoration, and a single-tooth implant.There are also specific criteria that mustbe addressed when choosing the appro-priate treatment option. The primaryconsideration among all treatment plansshould be conservation. Generally, thetreatment of choice should be the leastinvasive option that satisfies the expectedesthetic and functional objectives. Theorthodontist plays a key role in achiev-ing specific space requirements by po-sitioning teeth in an ideal restorativeposition. For example, canine substitu-tion can be an excellent, esthetic treat-ment option for replacing missing lat-erals. However, if it is used in the wrongpatient, the final result may be lessthan ideal.

SELECTING THE APPROPRIATE PATIENT

There are specific dental and facialcriteria that must be evaluated before

choosing canine substitution as thetreatment of choice for replacing missingmaxillary lateral incisors. They includemalocclusion and amount of crowding,profile, canine shape and color, and liplevel (Figure 1A through Figure 1C).1,2

If these selection criteria are fulfilled,the patient can expect a functional andesthetic final result.

MALOCCLUSIONThere are two types of malocclu-

sions that permit canine substitution.The first is an Angle class II malocclu-sion with no crowding in the mandib-ular arch. In this occlusal pattern, themolar relationship remains class II andthe first premolars are located in thetraditional canine position (Figure 2Aand Figure 2B). The second alternativeis an Angle class I malocclusion withsufficient crowding to necessitate man-dibular extractions. With either of thesetwo malocclusions, the final occlusalscheme should be designed so that thelateral excursive movements are in ananterior group function.2-4

Evaluation of the anterior tooth-sizerelationship is important when substi-tuting canines for lateral incisors. Theanterior tooth size excess that is creat-ed in the maxillary arch must often be

Managing Congenitally Missing LateralIncisors Part 1: Canine Substitution

Learning Objectives

After reading this article, thereader should be able to:

• evaluate specific patient selec-tion criteria and determine ifcanine substitution is an ap-propriate treatment alternativefor replacing congenitally miss-ing maxillary lateral incisors.

• identify how to position thecanines to satisfy functionalrequirements and achieveproper esthetics.

• recognize the importance ofinterdisciplinary treatmentplanning to achieve optimalanterior esthetics.

GGrreeggggoorryy AA.. KKiinnzzeerr,, DDDDSS,, MMSSDDAffiliate Assistant Professor

School of DentistryUniversity of Washington

Seattle, Washington

Private PracticeSeattle, Washington

VViinncceenntt OO.. KKookkiicchh JJrr,, DDMMDD,, MMSSDDAffiliate Assistant Professor

Department of OrthodonticsSchool of Dentistry

University of WashingtonSeattle, Washington

Abstract:Dentists often encounter patients with missing or malformed teeth. The maxillary lateral incisor is the sec-ond most common congenitally absent tooth. There are three treatment options that exist for replacingmissing lateral incisors. They include canine substitution, a tooth-supported restoration, or a single-toothimplant. Selecting the appropriate option depends on the malocclusion, specific space requirements, tooth-size relationship, and size and shape of the canine. The ideal treatment is the most conservative alternativethat satisfies individual esthetic and functional requirements. Often the ideal option is canine substitution.Although the orthodontist positions the canine in the most esthetic and functional location, the restora-tive dentist will often need to place a porcelain veneer or crown to re-create normal lateral incisor shapeand color. This article closely examines patient selection and illustrates the importance of interdisciplinarytreatment planning to achieve optimal esthetics. This article is the first of a three-part series discussing thethree treatment alternatives for replacing missing lateral incisors.

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2 ADVANCED ESTHETICS & INTERDISCIPLINARY DENTISTRY SEPTEMBER 2007—VOLUME 3, NUMBER 3

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reduced to establish a normal overbiteand overjet relationship.1 Therefore, acritical step in the patient-selection pro-cess is the completion of a diagnosticwax-up. This enables the orthodontistand dentist to evaluate the final occlu-sion, measure how much canine reduc-tion is necessary, and determine if anesthetic final result is achievable.3,4

PROFILEAfter one of the two occlusal criteria

has been satisfied, the profile should beevaluated. Generally, a balanced, rela-tively straight profile is ideal (Figure 3Aand Figure 3B). However, a mildly con-vex profile also may be acceptable (Figure4). A patient with a moderately convexprofile, retrusive mandible, and a defi-cient chin prominence may not be anappropriate candidate for canine substi-tution. A better alternative may be onethat addresses not only the dental mal-occlusion, but the facial profile as well.

CANINE SHAPE AND COLORThe shape and color of the canine are

important factors to consider for caninesubstitution to be considered “esthetic.”Naturally, the canine is a much largertooth than the lateral incisor it is replac-ing. With a wider crown and a more con-vex labial surface, a significant amountof reduction is often required for theorthodontist to achieve a normal oc-clusion and acceptable esthetics (Figure5). If a significant amount of enamelmust be removed to establish propersurface contours, the underlying dentinmay begin to show though the thin enam-el, thereby decreasing the esthetics.5 Ina canine with a greater degree of labialconvexity, dentin exposure can occurleading to the need for restorative inter-vention. Depending on the amount ofincisal edge wear of the canine, it may benecessary to restore the mesioincisal anddistoincisal edges to recreate normal lat-eral contours.2 The color of the naturalcanine should also be addressed andshould approximate that of the centralincisor (Figure 6). However, it is notuncommon for the canine to be moresaturated with color. The result is a tooththat is one to two shades darker than the

SEPTEMBER 2007—VOLUME 3, NUMBER 3 ADVANCED ESTHETICS & INTERDISCIPLINARY DENTISTRY 3

FFiigguurree 11AA tthhrroouugghh FFiigguurree 11CC Evaluation of specific dental and facial criteria is necessary when select-ing the appropriate patient for canine substitution.

FFiigguurree 33AA aanndd FFiigguurree 33BB A balanced facial profile is ideal.

FFiigguurree 44 A mildly convex profile may also beacceptable.

FFiigguurree 22AA aanndd FFiigguurree 22BB Maxillary canines erupting into the edentulous lateral incisor position (A).Class II molar relationship in canine substitution patients (B).

A B

C

A B

A B

Gnerally, the treatmentof choice should be theleast invasive option

that satisfies the expected esthetic andfunctional objectives.

central incisor. The most conservativeway to correct the color difference is toindividually bleach the canine. If thisfails to approximate the desired color, aveneer may be indicated.

A significant amount of incisal andpalatal reduction is generally requiredfor the orthodontist to vertically posi-tion the canine in the appropriate later-al incisor location. Unfortunately, thisexposes dentin that occasionally requiresrestorative intervention. Zachrisson hasshown that extensive grinding using dia-mond instruments with abundant waterspray cooling can be performed on youngteeth without long-term changes in toothsensitivity. However, he found that short-term increases in tooth sensitivity werenoted with temperature changes for 1 to3 days after grinding.5,6

Finally, crown width at the cemento-enamel junction (CEJ) should be evalu-ated on the pretreatment periapical ra-diograph to help determine the finalemergence profile (Figure 7). A caninewith a narrow mesiodistal width at theCEJ produces a more esthetic emergenceprofile than one with a wide CEJ width(Figure 8). The ideal lateral incisor sub-stitute is a canine that is the same coloras the central incisor, narrow at the CEJbuccolingually and mesiodistally, and hasa relatively flat labial surface and narrowmid-crown width buccolingually.

LIP LEVELIf the patient has an excessive gingi-

va-to-lip distance on smiling, the gin-gival levels will be more visible. Thismay be due to a vertical maxillary ex-cess or a hypermobile lip. The gingivalmargin of the natural canine should bepositioned slightly incisal to the central


FFiigguurree 88 A narrow width at the CEJ produces amore esthetic emergence profile.

FFiigguurree 77 Radiographic evaluation of crownwidth at the CEJ.

FFiigguurree 1100 The canine root eminence may beprominent.

FFiigguurree 66 Significant reduction is often required toachieve an acceptable occlusion and ideal esthetics.

FFiigguurree 55 The color of the canine and central inci-sor crowns should match.

FFiigguurree 99AA and Figure 9B Gingivectomy reestablishes proper gingival margin contours (A). Onemonth post-gingivectomy demonstrates nice gingival architecture (B).

FFiigguurree 1111 Significant equilibration of the labialand palatal crown surfaces is often required.

A B

The maxillary lateralincisor is the second most

common congenitallyabsent tooth.

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incisor gingival margin. This helps cam-ouflage the substituted canine. Occasion-ally, a gingivectomy may need to be per-formed to properly position the mar-ginal gingiva (Figure 9A and Figure9B). The gingival margin of the firstpremolar is naturally positioned morecoronally than the central incisor. Ifthis is a concern to the patient, crownlengthening can be performed followedby a veneer to establish ideal crown lengthsand gingival margin contours. Finally, inpatients with high smile lines, a promi-nent canine root eminence could also bean esthetic concern (Figure 10).4

TREATMENTProper bracket placement is impor-

tant when treating patients with caninesubstitution. The orthodontist shouldplace the brackets according to gingi-val margin height rather than incisaledge or cusp tip. Typically, the brack-ets on the canines should be placed ata distance from the gingival marginthat will erupt these teeth into theappropriate lateral incisor vertical posi-tion. As they erupt, a thicker portionof the crown comes into contact with

the mandibular incisors (Figure 11).This often causes prematurities thatmust be equilibrated periodically dur-ing the alignment stage of orthodontictreatment. During finishing, the ortho-dontist must reduce the width of thecanine interproximally to achieve optimalesthetics and a normal overjet relation-ship. After the teeth have been alignedand the canines reshaped, there is fre-quently a need for restorative treatmentto recreate ideal lateral incisor color andcontour. This may be accomplished withbleaching, composite resin, or a porce-lain veneer. Generally, the treatment ofchoice is the most conservative restora-tion that satisfies the patient’s estheticrequirements. A stepwise simulation ofthe typical treatment sequence can beseen in Figure 12A through Figure 12H.

SUMMARYCanine substitution can be an excel-

lent treatment alternative for congeni-tally missing maxillary lateral incisors.Patient selection depends on the type ofmalocclusion, profile, canine shape andcolor, and smiling lip level. Pre-treatmentevaluation of these selection criteria is

necessary to ensure treatment successand predictable esthetics.

The orthodontist typically plays thekey role in diagnosis and treatment ofthese patients. However, adjunctive res-torative treatment is often necessary torecreate ideal lateral incisor shape andcolor. Therefore, interdisciplinary treat-ment planning is necessary to achieveoptimal final esthetics.

REFERENCES1. Kokich VG. Managing orthodontic-restora-

tive treatment for the adolescent patient. InMcNamara JA, Brudon WL, eds. Orthodonticsand Dentofacial Orthopedics. 2001; AnnArbor, Michigan: Needham Press, Inc.

2. Zachrisson BU. Improving orthodonticresults in cases with maxillary incisors miss-ing. Amer J Orthod. 1978;73(3):274-289.

3. Tuverson DL. Orthodontic treatment usingcanines in place of missing maxillary lateralincisors. Amer J Orthod. 1970;58(2):109-127.

4. Senty EL. The maxillary cuspid and missinglateral incisors: Esthetics and occlusion. AngleOrthodontist. 1976;46:365-371.

5. Zachrisson BU, Mjor IA. Remodeling of teethby grinding. Amer J Orthod. 1975;68(5):545-553.

6. Thordarson A, Zachrisson BU, Mjor IA.Remodeling of canines to the shape of later-al incisors by grinding: A long-term clinicaland radiographic evaluation. Amer J OrthodDentofac Orthop. 1991;100(2):123-132.

SEPTEMBER 2007—VOLUME 3, NUMBER 3 ADVANCED ESTHETICS & INTERDISCIPLINARY DENTISTRY 5

FFiigguurree 1122AA tthhrroouugghh FFiigguurree 1122HH Irregular gin-gival architecture (A). Incisal wear affects propercrown width-to-length proportion (B). Ortho-dontic intrusion is necessary to facilitate restora-tive lengthening of the central incisors (C).Provisional composite restorations completed(D). Orthodontic extrusion of the canines (E).Ideal length of the canines as lateral incisors (F).Cuspal equilibration completed (G). Compositerestoration of the mesio-incisal corners (H).

A B C

D E F

G H


1. The treatment options that exist forreplacing missing lateral incisors include: a. canine substitution.b. a tooth-supported restoration.c. a single-tooth implant.d. all of the above

2. The primary consideration among alltreatment plans should be:a. function.b. esthetics.c. conservation.d. cost.

3. The specific dental and facial criteria that mustbe evaluated before choosing canine substitu-tion as the treatment of choice for replacingmissing maxillary lateral incisors include:a. malocclusion and amount of crowding.b. canine shape and color.c. age and gender of the patient.d. a and b

4. How many types of malocclusions permitcanine substitution?a. a. oneb. twoc. threed. four

5. To establish a normal overbite and overjetrelationship, what must often be reduced?a. The teeth directly posterior to the malocclusion.b. The anterior tooth size excess that is created in

the maxillary arch. c. The posterior tooth size that is created in the

mandibular arch.d. The teeth directly anterior to the malocclusion.

6. Depending on the amount of incisal edgewear of the canine, it may be necessary torestore which edges to recreate normallateral contours?a. distolateral and mesiobuccalb. lingual and labialc. mesioincisal and distoincisald. distolingual and mesiobuccal-lingual

7. A significant amount of what reduction is gen-erally required for the orthodontist to verticallyposition the canine in the appropriate lateralincisor location?a. incisal and palatalb. lingual and labialc. incisal onlyd. labial only

8. The ideal lateral incisor substitute is a caninethat is the same color as the central incisor,narrow at the CEJ buccolingually andmesiodistally, and has a relatively flat labialsurface and narrow mid-crown width:a. a. mesiodistally.b. labially.c. buccolingually.d. mesio-occlusally.

9. The orthodontist should place thebrackets according to gingival marginheight rather than:a. incisal edge.b. cusp tip.c. lingual angle.d. a and b

10. Typically, the brackets on the canines shouldbe placed at a distance from what gingivalmargin that will erupt these teeth into theappropriate lateral incisor vertical position?a. labialb. lingualc. gingivald. interproximal

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