atypical extraction of maxillary central incisors · consisted of extracting the ankylosed central...

CASE REPORT

Atypical extraction of maxillary central incisors

Guilherme Janson,a Danilo Pinelli Valarelli,b Fabr�ıcio Pinelli Valarelli,c Marcos Roberto de Freitas,d

and Arnaldo Pinzane

Bauru, Brazil

This case report describes a Class I crowded malocclusion with an ankylosed maxillary central incisor that wasin infraocclusion and labially displaced. The patient had wide maxillary teeth, and the option of extracting themaxillary central incisors followed by space closure, with lateral incisors substituting for the central incisors,was chosen. (Am J Orthod Dentofacial Orthop 2010;138:510-7)

Ankylosed permanent maxillary central incisorsin a growing patient are a clinical challengefor any orthodontist. Ankylosis results from

the fusion of a portion of the cementum of the root tothe adjacent alveolar bone.1 Permanent ankylosis fre-quently occurs after trauma, especially intrusive luxa-tion.2 This means that the tooth becomes an integralpart of the bone remodeling system, and, whereas theneighboring teeth erupt normally with alveolar growth,the ankylosed incisor does not erupt and eventually is ininfraocclusion with a higher gingival margin and isoften displaced labially.3

In these cases, extraction of the ankylosed tooth andspace closure might be a solution. Decisions about thedirection of treatment usually are based on severalfactors: type of malocclusion, space conditions, lateralincisor width and root length, and shape and shadeof the canines.4,5 From an orthodontic perspective,absence of maxillary anterior teeth can provide thespace and opportunity to alleviate a crowded dentitionor an enlarged horizontal overlap without extractingother teeth. However, this approach requires thelateral incisors to assume the functional and estheticrole of central incisors; the canines become the lateral

aProfessor and head, Department of Orthodontics, Bauru Dental School,

University of Sao Paulo, Bauru, Sao Paulo, Brazil.bPostgraduate student, Department of Orthodontics, Bauru Dental School,

University of Sao Paulo, Bauru, Sao Paulo, Brazil.cPrivate practice, Bauru, Brazil.dProfessor, Department of Orthodontics, Bauru Dental School, University of

Sao Paulo, Bauru, Sao Paulo, Brazil.eAssociate professor, Department of Orthodontics, Bauru Dental School,

University of Sao Paulo, Bauru, Sao Paulo, Brazil.

The authors report no commercial, proprietary, or financial interest in the

products or companies described in this article.

Reprint requests to: Guilherme Janson, Department of Orthodontics, Bauru

Dental School, University of Sao Paulo, Alameda Octavio Pinheiro Brisolla

9-75, Bauru, SP, 17012-901, Brazil; e-mail, [email protected].

Submitted, July 2008; revised and accepted, August 2008.

0889-5406/$36.00

Copyright � 2010 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2008.08.042

510

incisors, and the first premolars take the role of thecanines, with all the prosthetic camouflage that thesepositional changes require. Therefore, the objective ofthis article was to demonstrate this situation witha clinical patient and discuss the advantages anddisadvantages of this approach.

DIAGNOSIS AND ETIOLOGY

A boy, aged 13 years 11 months, was brought to theDepartment of Orthodontics at Bauru Dental School,University of Sao Paulo in Brazil, for evaluation. Hischief complaint was impaired esthetics because ofcrowding. He had moderate dental irregularity anda Class I biprotrusive malocclusion (Figs 1-3). Theleft maxillary central incisor was ankylosed, witha higher gingival level than the adjacent teeth. He hada traumatic episode at age 11 years, and the maxillaryleft central incisor was avulsed. The tooth receivedendodontic treatment and was reimplanted. Theperiapical radiograph shows the endodontic treatmentand the root resorption of the ankylosed maxillary leftcentral incisor (Fig 3, D). His face was symmetric, butthere was no passive lip competence at rest.

TREATMENT OBJECTIVES

The primary objectives were to eliminate the pa-tient’s crowding and excessive lip protrusion and to im-prove his facial appearance. The maxillary anteriorgingival margins would need to be leveled, and the max-illary left central incisor ankylosis and root resorptionwould need to be addressed, to establish acceptable an-terior dental esthetics.

TREATMENT ALTERNATIVES

Based on the objectives, 3 treatment options wereproposed. The first option consisted of extracting the 4first premolars to relieve the crowding and dentoalveo-lar protrusion followed by extraction of the ankylosed

mailto:[email protected]

Fig 1. Pretreatment facial and intraoral photographs.

American Journal of Orthodontics and Dentofacial Orthopedics Janson et al 511Volume 138, Number 4

central incisor. A single-tooth implant would be consid-ered as a prosthetic option to replace the extracted inci-sor after facial growth. A disadvantage of this optionwas that it would commit this young patient to a perma-nent prosthesis in an area of the mouth in which toothshade, gingival contour, and margins are critical andnot always easy to control.6-8 The second optionconsisted of extracting the ankylosed central incisor,the maxillary right first premolar, and the mandibularfirst premolars. The left lateral incisor would bemoved into the central incisor extraction site. Acomposite buildup would transform the lateral intoa central incisor.9 But the anterior dental esthetic resultwould be a problem. When a maxillary lateral incisorreplaces a missing central incisor, the problem is toduplicate the shape of the contralateral central incisor.

It is difficult to create an ideal crown shape because ofthe reduced clinical crown height of the lateral incisor.In addition, the mesial and distal surfaces of the crownmust be overcontoured, because of the narrower cervi-cal region of the lateral incisor.10 The third optionconsisted of extracting both maxillary central incisorsand the mandibular first premolars. This option seemedto be the most plausible, because the lateral incisorswere unusually large mesiodistally, and they could eas-ily be contoured as central incisors. The lateral incisorswould be moved into the central incisor position, andcomposite buildup would transform the lateral incisorsinto central incisors. The patient and his parentspreferred this option, because fewer teeth would beextracted, and the overall esthetics would be easier tomanage.

Fig 2. Pretreatment dental casts.

Fig 3. A, Pretreatment lateral cephalogram; B, pretreatment tracing; C, pretreatment panoramicradiograph; and D, pretreatment periapical radiograph.

512 Janson et al American Journal of Orthodontics and Dentofacial Orthopedics

October 2010

Fig 4. A, Bone; and B, gingival defect after extraction.

Fig 5. A-D, Progress intraoral photographs.


TREATMENT PROGRESS

After completing the initial preorthodontic proce-dures, extraction of the maxillary central incisors andmandibular first premolars was requested. When the an-kylosed central incisor was extracted, the labial bonewas lost as expected, and a significant vertical and buc-colingual defect appeared (Fig 4). The first molars werebanded, and preadjusted 0.022 3 0.028-in bracketswere placed on all remaining teeth. Prosthetic maxillarycentral incisors were fixed to the archwire at the extrac-tions sites (Fig 5).

The artificial teeth were gradually reduced proxi-mally, and both arches were leveled and alignedorthodontically. At the end of the alignment phase, the

narrow prosthetic teeth were replaced by 1 artificial toothfixed on a palatal plate, which was removed later to facil-itate space closure (Fig 5). Space closure was accom-plished with rectangular 0.019 3 0.025-in stainless steelarchwires and intramaxillary elastic chains. The anteriorextraction spaces were partially closed, leaving well-distributed interproximal spaces to be filled by compositerestoration of the maxillary lateral incisors. The bone de-fect was filled progressively, while the lateral incisorswere moved into the central incisor extraction sites.

At the end of orthodontic treatment, gingivectomyand direct composite buildup of the maxillary lateral in-cisors and canines transformed them into central andlateral incisors, respectively.

Fig 6. Posttreatment facial and intraoral photographs.


October 2010

RESULTS

The patient returned 6 months after the end oforthodontic treatment, with the gingivectomy andesthetic restorative treatment completed. Favorablefacial changes were observed with reduction ofthe biprotrusion and attainment of passive lip seal(Figs 6-8). Upon smiling, an ideal amount of toothstructure was displayed, and the anterior gingivalmargins were leveled. Intraorally, there was dramaticimprovement in dental esthetics. The arch lengthdeficiency was eliminated in both arches, satisfactorytooth alignment was obtained, and overbite andoverjet were improved (Figs 6 and 7). Extraction ofthe maxillary central incisors and mandibularpremolars facilitated coordination of the dental

midlines with the facial midline. The Class I molarrelationship was maintained, and a Class II caninerelationship was obtained, with the canines replacingthe maxillary lateral incisors. Composite restorationsand labial surface reductions were necessary totransform the maxillary canines into lateral incisors.Direct composite was built up on the lateral incisorsto transform them into central incisors. Thecephalometric superimposition showed significantchanges in the soft-tissue profile and the maxillomandib-ular relationship (Fig 8, Table). The posttreatment pano-ramic radiograph shows healthy supporting tissue andslight root blunting, despite the extensive tooth move-ment and lengthy treatment time (Fig 8). The patientand his parents were pleased with the final results.

Fig 7. Posttreatment dental casts.


DISCUSSION

An Angle Class I malocclusion with crowding anddentoalveolar biprotrusion is traditionally treated ortho-dontically with extraction of 4 first premolars.11 How-ever, this patient also had an ankylosed maxillarycentral incisor, which caused marked infraocclusion ofthe ankylosed tooth and migration and malpositioningof adjacent teeth. Additionally, the patient had widemaxillary anterior teeth, with the maxillary lateral in-cisors measuring 9 mm, compared with the averagewidth of 6.5 mm.12 These characteristics and the con-cern about anterior esthetics suggested the option ofextracting the maxillary central incisors and closingthe spaces by substituting the lateral incisors for thecentral incisors. But extracting an ankylosed tooth re-sults in vertical and horizontal loss of alveolar bone.3

A technique for extracting the ankylosed tooth andavoiding such bone loss is to remove the crown andleave the ankylosed root in the alveolus to be replacedby bone. In children, new marginal bone will then beformed coronal to the resorbing root. The height ofthe alveolar bone is thus improved vertically and pre-served in a faciolingual direction.13 Although this treat-ment alternative could have avoided the bone defect andimproved the conditions for subsequent prosthetic ther-apy, the selected treatment plan did not include a perma-nent prosthesis but, rather, the patient’s natural teeth,

which were moved into the extraction sites. Tooth move-ment to fill bone defects is possible. Alveolar bone willbe deposited ahead of the tooth if light and continuousforces are used and the gingival tissue is healthy.14,15

By moving the tooth slowly, the periosteum on thebuccal and lingual surfaces of the alveolus will formbone as the tooth is moved into the extraction site.15

The tooth is not moved like a mobile entity througha rigid bone channel but with its periodontal support.16

With the selected treatment protocol, bone graftsurgery and a permanent prosthesis were avoided. Inaddition, the final anterior esthetic appearance wassatisfactory. Nevertheless, the maxillary lateral incisorsand canines needed to be equilibrated, reshaped, and re-stored.17 For a successful esthetic and functional out-come, several issues had to be addressed and resolved.

When a maxillary lateral incisor is substituted fora missing central incisor, the problem is to simulatethe shape of the central incisor. It is difficult to createan ideal crown form because of the reduced clinicalcrown height. In addition, the mesial and distal surfacesof the crown must be overcontoured because of thenarrower cervical region of the lateral incisor.10 In thispatient, extraction of both maxillary central incisorsand substitution with the lateral incisors facilitatedcorrection of the maxillary anterior esthetics with gingi-vectomy and composite buildup.

Fig 8. A, Posttreatment lateral cephalogram; B, superimposition of pretreatment and posttreatmenttracings, on SN line centered at sella; C, posttreatment panoramic radiograph; and D, posttreatmentperiapical radiograph.


October 2010

When the canines occupy the lateral incisors’ posi-tions, the canines’ greater labiolingual dimension cancreate an occlusal interference with the mandibular inci-sors. Therefore, palatal trimming throughout treatment isnecessary when occlusal prematurities with the mandib-ular incisors are detected to prevent having the caninepositioned labially.9,17 The canine’s labial surfaceshould also be reduced to make it flatter. Studies haveshown that fairly extensive dental grinding can beperformed without significant discomfort, and withminor or no pulp and dentin reactions.18 Long-termobservations indicate that any unfavorable reactions aretemporary.19 The cusp tip and the labial surface werereduced to produce a flat incisal edge, and compositebuildups at the mesial and distal angles of the caninewere needed to complete the canine transformation.

When premolars are substituted for maxillary ca-nines, they should look and function like canines. Thepremolars were extruded relative to the adjacent teethand rotated mesially for a better contact point.9,17,20

The premolars’ roots were also torqued buccally tosimulate a canine prominence.9

Canine-protected occlusion is not feasible when thecanine is replaced by the premolar. As a result, the forces

generated through lateral excursive movements are placedon the roots of the first premolar21 or distributed by groupfunction.5,17,22 Some investigators fear loss of periodontalattachment, because of the stresses placed on thepremolars.22 However, long-term periodontal and occlu-sal studies on congenitally missing lateral incisors haveshown that space closure with premolars substituting forcanines was equally sound occlusally and preferableperiodontally to orthodontic space opening with pros-thetic replacement of the missing lateral incisor.23

The treatment plan for this patient addressed theproblem of the ankylosed central incisor, which was re-placed by adjacent teeth filling the extaction defect. Alltreatment objectives were satisfied, and the patient waspleased with the end result.

CONCLUSION

Extraction of the maxillary central incisors is nota usual treatment protocol in orthodontics. However,in some patients with ankylosis of the maxillary centralincisors and wide maxillary anterior teeth, this might bea good alternative to preserve tooth structure and avoidpermanent prostheses as long as the patient’s diagnostic

Table. Cephalometric treatment changes

Variable Pretreatment Posttreatment

Maxillary component

SNA 88.2� 87.2�

Co-A 90.5 mm 90.4 mm

A-Nperp 5.1 mm 2.2 mm

Mandibular component

SNB 83.6� 84.9�

Co-Gn 121.5 mm 127.4 mm

P-Nperp 3.1 mm 1.9 mm

Maxillomandibular relationship

ANB 4.6� 2.3�

Wits appraisal �0.3 mm �1.8 mm

NAP 7.3� 2.6�

Vertical and horizontal components

Mandibular plane angle (FMA) 26.2� 27.8�

SN.GoGn 30.7� 30.5�

Maxillary Dentoalveolar Component

Mx1.NA 22.9� 22.5�

Mx1-NA 6.9 mm 6.1 mm

Mandibular dentoalveolar component

Md1.NB 33.1� 33.8�

Md1-NB 9.4 mm 7 mm

Soft-tissue variables

H.NB 16.6� 10.7�

Nasolabial angle 100.3� 108.9�

Co-A, Linear distance from condylion to Point A; A-Nperp, linear dis-

tance from Point A to a line perpendicular to Frankfort plane from na-

sion; P-Nperp, linear distance from pogonion to a line perpendicular to

Frankfort plane from nasion; Co-Gn, linear distance from condylion to

gnathion; Mx1.NA, angle between the maxillary incisor long axis to

NA line; Mx1-NA, linear distance from the tip of the maxillary incisor

to NA line; Md1.NB, angle between the mandibular incisor long axis to

NB line; Md1-NB, Linear distance from the tip of the mandibular

incisor to NB line; NAP, NA to AP angle; H.NB, Angle between H

(Holdaway line) and NB lines.


characteristics will permit this plan. Additional cos-metic finishing on the anterior teeth might be necessaryto provide good esthetic results.

REFERENCES

1. Isaacson RJ, Strauss RA, Bridges-Poquis A, Peluso AR, Lindauer SJ.

Moving an ankylosed central incisor using orthodontics, surgery and

distraction osteogenesis. Angle Orthod 2001;71:411-8.

2. Malmgren O, Malmgren B, Goldson L. Orthodontic management

of the traumatized dentition. In: Andreasen JO, Andreasen FM,

editors. Textbook and color atlas of traumatic injuries to the teeth.

3rd ed. Copenhagen, Denmark: Munksgaard; 1993. p. 587-633.

3. Sabri R. Treatment of a Class I crowded malocclusion with an

ankylosed maxillary central incisor. Am J Orthod Dentofacial

Orthop 2002;122:557-65.

4. Zachrisson BU. Improving orthodontic results in cases with max-

illary incisors missing. Am J Orthod 1978;73:274-89.

5. McNeill RW, Joondeph DR. Congenitally absent maxillary lateral in-

cisors: treatment planning considerations. Angle Orthod 1973;43:24-9.

6. Oesterle LJ, Cronin RJ Jr. Adult growth, aging, and the single-

tooth implant. Int J Oral Maxillofac Implants 2000;15:252-60.

7. Thilander B, Odman J, Jemt T. Single implants in the upper inci-

sor region and their relationship to the adjacent teeth. An 8-year

follow-up study. Clin Oral Implants Res 1999;10:346-55.

8. Iseri H, Solow B. Continued eruption of maxillary incisors and

first molars in girls from 9 to 25 years, studied by the implant

method. Eur J Orthod 1996;18:245-56.

9. Newsome PR, Cooke MS. Modifying upper lateral incisors to

mimic missing central incisors: new ways to overcome old prob-

lems? Restorative Dent 1987;3:91-5:97, 99.

10. Kokich VG, Nappen DL, Shapiro PA. Gingival contour and clin-

ical crown length: their effect on the esthetic appearance of max-

illary anterior teeth. Am J Orthod 1984;86:89-94.

11. Tweed CH. Indication for the extraction of teeth in orthodontic

procedures. Am J Orthod Oral Surg 1944;30:405-28.

12. Garn SM, Lewis AB, Walenga AJ. Maximum-confidence values

for the human mesiodistal crown dimension of human teeth.

Arch Oral Biol 1968;13:841-4.

13. Malmgren B, Cvek M, Lundberg M, Frykholm A. Surgical treat-

ment of ankylosed and infrapositioned reimplanted incisors in ad-

olescents. Scand J Dent Res 1984;92:391-9.

14. Geraci TF, Nevins M, Crossetti HW, Drizen K, Ruben MP. Reat-

tachment of the periodontium after tooth movement into an osse-

ous defect in a monkey. 1. Int J Periodontics Restorative Dent

1990;10:184-97.

15. Spear FM, Mathews DM, Kokich VG. Interdisciplinary manage-

ment of single-tooth implants. Semin Orthod 1997;3:45-72.

16. Fontenelle A. A periodontal concept of induced tooth movement:

clinical evidence. Rev Orthop Dento Faciale 1982;16:37-53.

17. Tuverson DL. Orthodontic treatment using canines in place of

missing maxillary lateral incisors. Am J Orthod 1970;58:109-27.

18. Zachrisson BU, Mjor IA. Remodeling of teeth by grinding. Am J

Orthod 1975;68:545-53.

19. Thordarson A, Zachrisson BU, Mjor IA. Remodeling of canines to

the shape of lateral incisors by grinding: a long-term clinical and

radiographic evaluation. Am J Orthod Dentofacial Orthop 1991;

100:123-32.

20. Sabri R. Management of missing maxillary lateral incisors. J Am

Dent Assoc 1999;130:80-4.

21. Balshi TJ. Osseointegration and orthodontics: modern treatment

for congenitally missing teeth. Int J Periodontics Restorative

Dent 1993;13:494-505.

22. Nordquist GG, McNeill RW. Orthodontic vs. restorative treatment

of the congenitally absent lateral incisor—long term periodontal

and occlusal evaluation. J Periodontol 1975;46:139-43.

23. Senty EL. The maxillary cuspid and missing lateral incisors:

esthetics and occlusion. Angle Orthod 1976;46:365-71.

atypical extraction of maxillary central incisors · consisted of extracting the ankylosed central...

Documents