CLINICIAN’S CORNER

Treatment of an ankylosed maxillary incisor byintraoral alveolar bone distraction osteogenesis

YongIl Kim,a SooByung Park,b WooSung Son,c SeongSik Kim,d YongDeok Kim,e and James Mahf

Busan, Korea, and Los Angeles, Calif

An ankylosed tooth and adjacent alveolar process can lead to the development of an open bite, an unestheticsmile line, and abnormal function in mastication. Intraoral alveolar bone distraction osteogenesis is an optionfor treating an ankylosed tooth. The purpose of this clinical report was to show the treatment of a growing pa-tient with an ankylosed maxillary central incisor. A simple tooth-borne intraoral distractor was made with anexpansion screw and 0.9-mm stainless steel wire, which enabled it to move easily. Intraoral alveolar bone dis-traction osteogenesis will give the best results in patients with favorable root length and severely resorbed al-veolar bone in the vertical dimension. (Am J Orthod Dentofacial Orthop 2010;138:215-20)

Ankylosis means ‘‘failure to move’’ in Greek; itrefers to the fusion of a tooth and the alveolarbone that prevents the tooth from physiologic

and orthodontic movements. Deciduous molars oftenbecome ankylosed, but impacted canines and trauma-tized maxillary incisors can also be affected.1,2 Lackof normal physiologic tooth movements, such as thosethat occur with mastication and occlusion, can bea causative factor in ankylosis. Andreason3 suggestedthat splinting traumatized teeth, preventing physiologicmovements, would result in ankylosis.

If ankylosed teeth are misdiagnosed or unrecog-nized, treatment progress and results can be severelycompromised. Unfortunately, it is difficult to diagnoseankylosed teeth in the early stages. Key features leadingto diagnosis include lack of mobility and orthodonticmovement, tipping of adjacent teeth, ditching of the al-veolar process, infraocclusion, and a characteristic dullsound on percussion.

aClinical assistant professor, Department of Orthodontics, School of Dentistry,

Pusan National University, Busan, Korea.bProfessor, Department of Orthodontics, School of Dentistry, Pusan National

University, Busan, Korea.cProfessor, Department of Orthodontics, School of Dentistry, Pusan National

University, Busan, Korea.dAssociate professor, Department of Orthodontics, School of Dentistry, Pusan

National University, Busan, Korea.eAssociate professor, Department of Oral and Maxillofacial Surgery, School of

Dentistry, Pusan National University, Busan, Korea.fAssociate clinical professor, Division of Craniofacial Sciences and Therapeu-

tics, School of Dentistry, University of Southern California, Los Angeles, Calif.

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

ucts or companies described in this article.

Reprint requests to: SooByung Park, Department of Orthodontics, School of

Dentistry, Pusan National University, Ami 1ga 10, Busan, Korea; e-mail,

sbypark@pusan.ac.kr.

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

0889-5406/$36.00

Copyright � 2010 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2008.07.024

Ankylosis can have regional dentoalveolar and morewidespread craniofacial results. Infraocclusion of anankylosed tooth or tipping of adjacent teeth and thealveolar process can lead to an open bite in the anterioror posterior teeth, midline shifts, changes in facialvertical dimensions, unesthetic face and smile line,occlusal disharmony, and abnormal functions in masti-cation. The most common treatment for ankylosis isextraction.1,2 In a growing patient, extracting anankylosed tooth often allows for better developmentof the dentoalveolar process in this region. Theadjacent teeth continue to erupt normally and bringthe periosteum over the extraction site with them,thereby developing the alveolar bone. In addition, anysucceeding permanent teeth will erupt and continue todevelop the alveolar process.

In an adult, various procedures such as prosthodonticrestorations, luxation, and surgical repositioning areavailable, depending on the extent and the position ofthe tooth. Surgical repositioning might involve a single-tooth osteotomy alone or with distraction osteogenesis.

Since Ilizarov4 pioneered distraction osteogenesis,McCarthy et al,5,6 Toth et al,7 Molina and Ortiz Monas-terio,8 and Guerrero et al9 made improvements anddemonstrated many successful cases in the 1990s.Alveolar bone distraction osteogenesis was introducedto augment the alveolar bone both vertically andhorizontally.10-12

In this clinical report, we present the treatment ofa growing patient with an ankylosed maxillary incisortreated by intraoral alveolar bone distractionosteogenesis.

CASE REPORT

The patient was a girl, aged 11 years 11 months,who had bumped against the corner of a desk and

215

Fig 1. Pretreatment intraoral photographs, lateral cephalograph, and periapical and panoramicradiographs.

Fig 2. Posterior movement of the maxillary molars, with the ankylosed maxillary left central incisorproviding indirect anchorage.

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damaged her maxillary incisors when she was 7 yearsold. The incisors were reimplanted, but the left centralincisor eventually became ankylosed, preventing furthergrowth of the alveolar bone, creating an open bite in themaxillary incisors, and resulting in tilting of theadjacent teeth as further dentoalveolar growth anddevelopment occurred. The diagnosis of ankylosis ofthe maxillary incisor was based on loss of movement,infraocclusion, lack of radiographic periodontal liga-ment space, tilting of adjacent teeth and the alveolarprocess, and a dull sound on percussion. Additionaldiagnosis included a skeletal Class II Division 1

malocclusion with cephalometric values of SNA of87.1�, SNB of 79.1�, and ANB of 7.9� (Fig 1).

In consideration of the patient’s age and the occlusaland esthetic goals, conventional approaches were ruledout. Leaving an ankylosed maxillary left central incisorin place and restoring it prosthetically would furtherimpede vertical development of the alveolar bone, in-crease the infraocclusion, and severely compromisethe esthetic results. However, if the tooth was extracted,significant bone would be lost in this area, and recessionof the adjacent periodontal support could occur. Boneaugmentation would be required at extraction and again

Fig 3. Intraoral tooth-borne distractor.

Fig 4. Interdental and subapical osteotomy.

American Journal of Orthodontics and Dentofacial Orthopedics Kim et al 217Volume 138, Number 2

after growth. If a bridge was placed at this time, the cen-tral incisor crown would be significantly longer than thecontralateral tooth, or there would be a large gap underthis pontic. These compromises were considered unac-ceptable; therefore, extraction and prosthodontic treat-ment were excluded.

The 2 procedures considered to alter the vertical po-sition of the maxillary incisor and the alveolar bonewere a single-tooth osteotomy and alveolar bone dis-traction ostegenesis. However, the ankylosed incisorneeded to be repositioned by approximately 8 mm.This large movement with a single-tooth osteotomywould be impossible because of gingival pull. In con-trast, a great deal of bony movement, histogenesis,and tissue remodeling would be possible with distrac-tion osteogenesis. Therefore, this was considered thetreatment of choice. The plan was to take advantageof the ankylosed maxillary left central incisor and useit as anchorage to distalize the molars. Subsequently,the ankylosed tooth would be moved by distraction os-teogenesis with a tooth-borne alveolar bone distractor.

Several teeth in the maxilla were banded, and an im-pression was taken to construct an indirect anchoragetranspalatal appliance with a 0.9-mm stainless steelarchwire (Fig 2). This would be used to consolidate ananterior anchor unit for the distalization of the posteriormaxillary dentition.13

After the maxillary molars were adequately distal-ized, .022-in slot fixed appliances were placed on themaxillary and mandiblular teeth to provide adequate

arch length for the maxillary left central incisor. Afterpresurgical orthodonthic treatment, an intraoral tooth-borne distractor was fabricated with an expansion screw(#198-1223, Forestadent, Pforzheim, Germany) (Fig 3).

The ankylosed tooth was banded and an impressiontaken. After preexpanding the screw to its final position,it was adapted to the band and the 0.9-mm stainless steelwire. The archwire was carefully soldered to the preex-panded screw and the band. This is important to deter-mine the direction of the distraction. Six to 8 spurs,1.5 to 2 mm long, were soldered to this wire at interden-tal spaces for stability.

With the patient under local anesthesia, an interden-tal osteotomy and subapical osteotomy were performedaround the maxillary left central incisor (Fig 4). Mobil-ity of the osteotomy block containing the incisor and theoperation of the distractor were confirmed. A key aspectof the surgical procedure was to conserve as muchattached gingiva as possible during the incision andsuturing.

After a 5-day latency period, distraction was started(Fig 5). Distraction is typically carried out at a rate ofapproximately 1 mm per day for larger segments ofthe maxilla and mandible, but 0.5 to 0.8 mm per daywould be appropriate for this procedure in alveolarbone.14 However, in consideration of the strong resis-tance to movement of the osteotomy block in the earlystages of distraction, we elected to distract at the rateof 1 mm per day for the first 4 days. To induce histogen-esis, the rate was decreased to 0.4 mm per day.15 An

Fig 5. Intraoral photographs and radiographs during distraction osteogenesis.

Fig 6. Fine adjustment with nickel-titanium overlay wire.

218 Kim et al American Journal of Orthodontics and Dentofacial Orthopedics

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overcorrection of 1 mm was planned to account forcontinued vertical growth of the dentition and the poten-tial for relapse. After 2 weeks of consolidation, the dis-tractor was removed, and the maxillary left centralincisor bracket was ligated onto the .019 3 .025-inheat-activated nickel-titanium archwire (Fig 6). Furtherhealing, remodeling, and consolidation of the osteot-omy site continued while the archwire sequence pro-gressed to .019 3 .025-in stainless steel (Fig 7). Thefinal results are shown in Figure 8.

DISCUSSION

For clinicians, bony deficiencies in the dentoalveo-lus complicate treatment, particularly in growing pa-tients, because the situation often worsens withgrowth and time. In many instances, bony deficienciesor early loss of permanent teeth causes adjacent alveolarbone to resorb and periodontal tissues to recede, neces-sitating additional surgery. Intraoral alveolar bonedistraction osteogenesis can initiate histogenesis,regenerate tissues, and compensate for vertical alveolarbone loss.11,12

Ankylosis of a tooth during its development is rare;however, when it occurs, it can prevent vertical growthof the alveolar bone, leading to bony deficiency.16,17

Fortunately, permanent molars are not ankylosed asoften as deciduous molars in growing patients.However, reimplantation after injury or impaction isa common cause of ankylosis in the permanentdentition. Andreason3 suggested that splinting injured

teeth without allowing for physiologic movement wouldresult in ankylosis. Maxillary incisors are traumatizedmost frequently; thus, they occasionally become anky-losed, leading to arrested vertical growth of the alveolarbone.

Ankylosed teeth are often discovered because oftheir infraocclusion.2 This has regional effects and canresult in open bites in the maxillary incisors and unes-thetic smiles, and ultimately lead to midline shifts andtilting of adjacent teeth and alveolar bone.

In growing patients, ankylosed teeth are often ex-tracted to reduce their interference with vertical devel-opment of alveolar bone.18,19 Prosthodontic treatmentalone can produce unacceptable results, particularly ifthe dentition and alveolar bone continue to grow anddevelop. Extraction of the ankylosed tooth results insignificant loss of alveolar bone, ultimately creatinga need for bone augmentation. Because of theselimitations, an option for managing ankylosed teeth ingrowing patients is alveolar bone distraction.

In this clinical report, the patient’s maxillary leftcentral incisor was ankylosed without severe rootresorption. Extraction was not a viable treatment option,although the tooth was severely infraoccluded and thepatient did not have sufficient attached gingiva. Thiswas a severe limitation for a single-tooth osteotomyalone, because this would limit bony movements andultimately the stability of the alveolus. Therefore, alve-olar bone distraction osteogenesis was considered thebest treatment alternative to produce optimal occlusaland esthetic results.14

Fig 7. Finishing.

Fig 8. Posttreatment intraoral photographs, lateral cephalograph, and periapical and panoramicradiographs.

American Journal of Orthodontics and Dentofacial Orthopedics Kim et al 219Volume 138, Number 2

The process of intraoral alveolar bone distractionhas unique challenges because of the nature and typesof tissues, such as the attached gingival and the denti-tion. Therefore, the design of intraoral distractors is ofgreat importance. Intraoral distractors used in the pastrequired direct attachment to the alveolar bone, typi-cally with bone screws. This necessitated additionalsurgery to remove the screws. Recent developmentshave led to new designs of tooth-borne alveolar bonedistractors with modified expansion screws.13,20,21

A challenging aspect of alveolar bone distraction isdirectional control. It is difficult to regulate the directionof distraction if the distractor is directly attached to boneor to all maxillary teeth. We used a 0.9-mm stainlesssteel wire, supported by the maxillary teeth to allowfor directional control.

Recently, several authors have described bonemolding in the period of consolidation of distraction os-teogenesis. Kinzinger et al22 adapted the floating boneconcept to distraction osteogenesis and adjusted the

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wires when callus was formed. In our patient, the rect-angular archwire was carefully adjusted with a reducedconsolidation period after achieving adequate verticaldistraction. Adjustments were primarily aimed at bring-ing the palatally positioned tooth into the arch line.

The dentoalveolus continues to change for sometime into adulthood. Thilander et al23 followed 10 pa-tients for 8 years after they received dental implants.All showed changes detected with cephalometric radio-graphs during the first 3 years. Continued growth anddevelopment resulted in implant displacements of 0.46to 0.95 mm less than adjacent teeth. This differencewas greater if the patients had more growth remaining.In a sample of adults (ages, 25-45 years), Forsberget al24 reported continued increases in dentoalveolardimensions, concluding that there is small but constantvertical growth in the maxillary and mandibular denti-tions. This suggests that a small amount of continueddentoalveolar development must be accounted forwhen determining the amount of distraction required.In addition, potential relapses and the actual amountof discrepancy must be factored in when performingvertical distraction osteogenesis in growing patients.Unfortunately, it is not possible to accurately determinethe exact amount of additional dentoalveolar develop-ment. More long-term studies of dentoalveolar changes,particularly after clinical procedures such as dentalimplants and dentoalveolar distraction, are needed.

CONCLUSIONS

We presented a patient with an ankylosed maxillarycentral incisor with favorable root length, severe verti-cal alveolar bone height discrepancy, and adjacentdental collapse and tipping. Treatment includeddentoalveolar distraction osteogenesis and a strategicbiomechanical plan to provide excellent occlusal andesthetic results.

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