Canine autotransplantation: Effect of extraction site ... · cally. After orthodontic treatment, a veneer could be placed on the canine to match the morphology of the contralateral

CASE REPORT

Canine autotransplantation: Effect of extractionsite preservation with a titanium prosthesis anda bioresorbable membrane

Nan Rua and Yuxing Baib

Beijing, China

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The permanent canine is the most frequently displaced or impacted tooth. The standard treatment for animpacted canine includes surgical exposure and orthodontic alignment. Autotransplantation is a treatmentalternative for canines with complete root formation. The purpose of this article is to report a canine autotrans-plantation where the extraction site was preserved with a titanium prosthesis and a bioresorbable membrane.The autotransplanted canine had minimal root resorption and no ankylosis. (Am J Orthod Dentofacial Orthop2013;143:724-34)

Permanent canines are important both functionallyand esthetically. However, they are also the mostfrequently displaced and impacted teeth in the den-

tition.1 The standard method to manage an impacted ca-nine includes surgical exposure and orthodonticalignment, but such treatment is often impractical.

Autotransplantation of teeth with completed rootformation is an alternative to orthodontic treatment,and this process refers to the autogenous repositioningof a tooth in a surgically formed socket to replace a tooththat might be congenitally missing or have severe caries.

Autogenous transplantation of impacted canines wastried by Widman in 1915.1 Root resorption is oftenfound after autotransplantation surgery. The prevalenceof external root resorption is high, and it is the mostcommon cause of the eventual failure of the autotrans-planted teeth.2 Periodontal healing is responsible forroot resorption after autotransplantation. Periodontalcells located at the surface of the transplanted rootsare known to facilitate ankylosis and root resorption.Preparing a suitable recipient site and protecting the

the Department of Orthodontics, School of Stomatology, Capital Medicalrsity, Beijing, China.candidate.ssor.uthors report no commercial, proprietary, or financial interest in thects or companies described in this article.t requests to: Yuxing Bai, Department of Orthodontics, School oftology, Capital Medical University, Tiantan Xili 4, Chongwen District,g, China 100050; e-mail, [email protected], February 2012; revised and accepted, April 2012.5406/$36.00ight � 2013 by the American Association of Orthodontists./dx.doi.org/10.1016/j.ajodo.2012.04.027

periodontal cells from damage should increase thesuccess rate of autotransplantation.

In this case report, we describe extraction sitepreservation by fixation with a titanium prosthesis anda bioresorbable membrane, and their effects on theautotransplanted canine during and after orthodontictreatment.

DIAGNOSIS AND ETIOLOGY

The patient was a 14-year-old adolescent boy whowas referred by his dentist for an orthodontic consulta-tion with the chief complaint of a missing canine. He washealthy with no remarkable medical history and had nocontraindication for dental treatment. No signs orsymptoms of temporomandibular disorders accordingto the guidelines of the American Academy of OrofacialPain were reported.

The pretreatment records showed that the patienthad normal vertical facial proportions, a straight profile,and good facial symmetry. The pretreatment intraoralphotographs showed that the maxillary left deciduouscanine was retained and decayed (Fig 1).

Analysis of the dental casts disclosed aClass IImolar re-lationship tendency on the both sides and several mildlyrotated teeth. The maxillary overjet was 3.5 mm, and thepatient had a normal overbite and no crossbites. Themaxillary andmandibularmidlineswere coincident (Fig 2).

The panoramic radiograph showed that the maxillaryleft canine was impacted at the apex of the maxillary leftlateral incisor, and this incisor had obvious root resorp-tion because of the impacted canine. No radiographicsigns of the third molars were visible at the beginningof the treatment (Fig 3).

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http://dx.doi.org/10.1016/j.ajodo.2012.04.027

Fig 1. Pretreatment photographs.

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The cephalometric evaluation confirmed a Class Iskeletal relationship with an average growth pattern.The maxillary dentition was placed normally on itsbase, but the mandibular dentition was retracted. Thevertical relationships appeared to be within normal limits(Table).

TREATMENT OBJECTIVES

Autotransplantation of a tooth can obviously shortenthe treatment time when a suitable donor tooth isavailable and the anatomic circumstances permit thisprocedure. The treatment objectives included extractingthe retained deciduous canine, transplanting theimpacted canine into the extraction site, and establishinga Class I molar relationship on both sides along withnormal overjet and overbite.

American Journal of Orthodontics and Dentofacial Orthoped

TREATMENT ALTERNATIVES

One treatment alternative for this patient was toextract the deciduous canine and move the permanentcanine into position orthodontically. This option wouldtake 2 to 3 years and could jeopardize the root of themaxillary left lateral incisor.

The second option was to extract both the deciduouscanine and the impacted permanent canine, adjust thecanine space orthodontically, keep the space untiladulthood, andplace an implant in the canine space.How-ever, from the esthetic point of view, the patientwould nottolerate the missing canine throughout adolescence. Fur-thermore, after removal of the tooth, the alveolar processeswould begin to atrophy, affecting the maintenance of thealveolar bone and the attached gingiva.

The other option was extraction of the left lateralincisor and the deciduous canine with canine

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Fig 2. Pretreatment dental casts.

Fig 3. Pretreatment lateral cephalogram and panoramicradiograph.

Table. Cephalometric analysis

Pretreatment PosttreatmentTwo years

posttreatmentSNA (�) 83.1 84.3 85.2SNB (�) 81.5 83.2 84.2ANB (�) 1.6 1.1 1FMA (�) 29.3 29.4 29.7U1 to NA length (mm) 2.4 7.5 7.3U1 to NA angle (�) 16.8 30.5 30L1 to NB length (mm) 1.6 5.3 5.5L1 to NB angle (�) 22.7 29.1 29Wits (mm) �1.8 �3.3 �3.5

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transposition into the lateral incisor site orthodonti-cally. After orthodontic treatment, a veneer could beplaced on the canine to match the morphology ofthe contralateral incisor, and a future implant wouldbe placed in the left canine position. However, thesuccess of this treatment option depends on thesuccess of the extrusion of the impacted canine, thefuture cost of an implant, and the appearance ofthe incisor's gingiva.

TREATMENT PROGRESS

After discussion with the oral surgeon, whoperformed the autotransplant surgery, we decided totreat with full fixed appliances, incorporating extractionof the deciduous canine and autotransplantation of theimpacted canine into the extraction site.

Journal of Orthodontics and Dentofacial Orthopedics

Fig 4. Computerized tomography scan showed a complete transposition, with the crown of the caninemesial to the root of the lateral incisor and palatal to the root of the left incisor, and the maxillary leftincisor had obvious root resorption.

Fig 5. A, Nickel-titanium open-coil spring was used to gain more space for the donor tooth (0.019 30.025 in);B, the deciduous canine was extracted, and the extraction site was kept for the titanium tooth;C, the impacted canine was extracted and transplanted into the extraction site; D, the impacted caninewas brought into the arch with light 0.012-in nickel-titanium wire.

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Before the orthodontic treatment, we could notaccurately identify the position of the impacted toothon the pretreatment panoramic radiograph. A medicalcomputerized tomography scan was planned to assessthe position of the canine relative to the root of thelateral incisor.

The composite image showed complete transposi-tion, with the crown of the canine mesial to the rootof the lateral incisor, yet palatal to the root of the incisor(Fig 4). Degeneration of alveolar bone would most likelyoccur after extraction; thus, to maintain the height ofthe alveolar ridge, a pure titanium canine prothesiswas planned for the extraction site. With the computer-ized tomography images, 2 acrylic teeth were made, and


the sizes were the same as the impacted tooth. One wasfor the autotransplantion surgery to prepare therecipient site, and the other was invested, cast, andsoldered with special equipment in an oxygen-free envi-ronment to produce a pure titanium canine prothesis.

Fixed appliances (Mini Uni-Twin, 0.022-in slot; 3MUnitek, Monrovia, Calif) were placed on the maxillary andmandibular teeth in February 2009. A nickel-titaniumopen-coil springwas used to gainmore space for the donortooth.Within 6months of leveling and alignment, stainlesssteel overlay arches (0.0193 0.025 in) were placed in themaxillary and mandibular arches for stabilization, and thespace in the recipient site was prepared for the transplant(Fig 5,A). The recipient site was the same size as the acrylic


Fig 6. A, The impacted canine was extracted; B, the xenogeneic graft of deproteinized bovine bonemineral was placed between the root and the gingival flap; C, the bioresorbable membranes wereplaced between the bone substitute and the gingival flap; D, the gingival flap was closed; E, theautotransplanted surgery was finished.

Fig 7. Treatment progress radiographs: A, immediately;B, 1 month later; C, 6 months later; D, 10 months afterthe transplantation of the impacted canine.

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tooth. At this time, themolar and canine relationships wereClass I on the right side, with a Class II tendency on the leftsidebecause the impacted caninewas smaller than the rightcanine.


The deciduous canine was extracted, and theextraction site was maintained to implant the titaniumcanine prosthesis (Fig 5, B). After a month of recovery,the titanium prosthesis was removed, and the extrac-tion site was the same as the titanium prosthesis,with no inflammation. The impacted canine was ex-tracted and transplanted into the extraction site. Be-cause there was not enough bone on the buccalalveolar process, we placed a xenograft of deprotei-nized bovine bone mineral (Bio-Oss; Geistlich, Wolhu-sen, Switzerland) between the root and the gingivalflap. We also placed a bioresorbable membrane be-tween the bone substitute and the gingival flap (Fig6). We removed the donor tooth's occlusal contactfor early stability in the first 2 weeks and useda 0.012-in nickel-titanium segment wire to level andalign the autotransplanted tooth into its normal posi-tion (Fig 5, C and D). One month after the transplan-tation surgery, root canal treatment was performed(Fig 7, B). During the final stages, Class II elasticsand anterior box elastics were used to idealize the oc-clusion.

After 18 months of treatment, the appliances wereremoved, and a Hawley retainer was delivered withinstructions to wear it for 24 hours each day for the firstyear and at night in the second year. We also asked thepatient not to chew hard food with the maxillary leftlateral incisor because of its short root.


Fig 8. Posttreatment photographs.

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TREATMENT RESULTS

After 18 months of treatment, the autotransplantedcanine was in a good position in the arch. Clinically,there was no evidence of attachment loss of the tooth.The gingival margin of the canine was not ideal butcould be idealized with a gingivectomy. Ideal overjetand overbite were achieved with adequate caninedisclusion and protrusive guidance. Ideal Class Imolar and canine relationships were achieved as well(Figs 8 and 9).

On the panoramic radiograph, no signs of ankylosis,mobility, increased pocket depth, or inflammation in therecipient site were detected. There was a little apical rootresorption and a small notching of the root on the distalaspect near the alveolar crest of the canine. The rootresorption of the maxillary left central incisor hadstabilized (Fig 10).


The pretreatment and posttreatment cephalometricanalyses were outlined. The mandibular incisors wereideal in their posttreatment relationships to the nasion-supramentale line. The protrusion of the maxillary inci-sors and the lip to E-plane distance were maintained(Fig 11). The posttreatment facial esthetics were excel-lent, and the patient was satisfied with the results ofthe treatment.

The treatment results were maintained after 2 yearsof retention, and the occlusion had improved (Fig 12).The periapical radiograph of the transplanted caninetaken 2 years posttreatment showed no obvious rootresorption, and the notching of the root on the distalaspect near the alveolar crest of the canine had repaired(Fig 13). The panoramic radiograph after 2 years ofretention showed that all other teeth were in goodcondition, without root resorption (Fig 14).


Fig 9. Posttreatment dental casts.

Fig 10. Posttreatment lateral cephalogram and pano-ramic radiograph.

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Superimposition of the posttreatment and the 2-yearsposttreatment tracings showed that facial growth hadcontinued during the 2 years (Fig 15).

DISCUSSION

This patient had an impacted canine and severeincisor root resorption. Both the crown and the rootof the canine were mesial to the crown and theroot of the lateral incisor. The case was further com-plicated because the canine was unerupted, and theconventional radiographs offered conflicting evidenceof its relative position to the lateral incisor. The pan-oramic and periapical films could not provide accu-rate assessments of the relative position of theimpacted tooth or of the root resorption of the lateralincisor because of the 2-dimensional images. How-ever, the ultimate success of the treatment planhinged on accurate assessment of the relative positionof the impacted tooth. There have been reports ofsuccessful use of computerized tomography in thelocalization of impacted canines.3,4 Computerizedtomography can provide buccolingual, axial,coronal, sagittal, and panoramic views to identifyroot resorption of a lateral incisor. Furthermore,with the software, the computerized tomographyimages can be accurately converted into 3-dimensional images, which are helpful for theextraction procedure and the creation of a toothprototype.

May 2013 � Vol 143 � Issue 5 American Journal of Orthodontics and Dentofacial Orthopedics

Fig 11. Pretreatment and posttreatment superimposed cephalometric tracings: A, superimposed onthe sella-nasion plane at sella; B, superimposed on the posterior portion of the hard palate; C, super-imposed on the mandibular plane at menton.

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Autotransplantation of teeth has evolved as anaccepted treatment option in orthodontics over thelast 3 or 4 decades.5-9 Andreasen et al10 reported survivalrates of 95% and 98% for teeth transplanted withincomplete and complete roots, respectively. Pogrel11

reported a success rate of 72%. The most relevantcomplications in autotransplantation of teeth that affectthe success rate are inflammatory or replacementresorption. Inflammatory resorption could lead to toothloss without proper endodontic treatment.12 Toothankylosis can be visible on radiographic examinationsas the disappearance of the periodontal ligament space,with or without resorption of the root, and, clinically, asa high metallic sound with the percussion test. Thiscomplication, although considered untreatable, can besymptomless, and the tooth can function normally for10 to 15 years.13,14

The prognosis of autotransplantation has beengreatly improved with the prevention of infection inmedical science, but some unfavorable results such asroot resorption and ankylosis still remain.15-20 It wasreported that the successful prognosis of transplantedteeth depends on the following factors: the conditionof the remaining periodontal ligament attached tothe extracted donor tooth,21-23 the adaptation of the


donor tooth to the socket,24 the duration and themethod of splinting after transplantation,25,26 andthe timing of endodontic treatment of thetransplanted teeth.23,27

Based on those findings, an attempt to reduce thedamage to the periodontal ligament was an acceptablesolution for us. We created a prototype acrylic toothmade of pure titanium and transplanted it into theextraction site for healing. Titanium is a biologicallycompatible metal and widely used in medicine anddentistry. After it was placed in the socket for 1 month,the socket healed quite well around the prosthesiswithout inflammation, and the alveolar process ofthe extraction site remained at a constant height.This method avoided removing much bone duringpreparation of the extraction site and allowed forstable insertion of the transplanted tooth in theextraction site.

We also used somemethods to prevent root resorptionor ankylosis. During the autotransplantation procedure,the buccal alveolar process needed grafting. To fix thedonor tooth and sustain the height of the alveolarprocess, we placed the bone substitute between theroot and the gingival flap, and then applieda bioresorbable membrane between the bone substitute


Fig 12. Two years posttreatment.

732 Ru and Bai

and the gingival flap. This treatment is derived from theconcept of guided tissue regeneration. While improvingthe osseous conditions of the recipient site, the use ofa membrane permitted recolonization of the periodontalcells into the extraction site and optimized the periodon-tal healing.28

Some reports have focused on the prevention ofankylosis. Mine et al29 reported that an occlusal stimulusafter transplantation might promote regeneration of theperiodontal ligament. Some clinical studies havesuggested that the preapplication of mechanical stimulito the donor teeth might stimulate the periodontalligament, prevent ankylosis, reduce the damage to theperiodontal ligament, and prevent root resorption afterreplantation.30,31 Nevertheless, the jiggling forces usedin those experiments were also reported to causegreater destruction of the periodontium, including rootresorption.32,33 During the first 2 weeks after the


autotransplantation procedure, we removed the donortooth's occlusal contact to prevent any jiggling forceson it. Then we applied a light force to the donor toothto stimulate the periodontal ligament to reduce rootresorption or ankylosis. It was apparently helpful inour patient to prevent ankylosis.

The final result demonstrated mild apical rootresorption of the maxillary left canine and severeroot resorption on the maxillary left lateral incisor.Compared with the incisor root before treatment, theroot length did not change much. Several authorshave looked at the long-term consequences of apicalroot resorption. Falahat et al34 demonstrated favor-able long-term prognoses in a long-term follow-upof resorbed maxillary incisors, and no incisors lostvitality or exhibited ankylosis. Remington et al35

suggested that orthodontically induced root resorp-tion does not progress once the appliances are


Fig 13. Periapical radiograph of the canine taken 2 yearsposttreatment showed no obvious root resorption.

Fig 14. Lateral cephalogram and panoramic radiographat 2 years posttreatment.

Fig 15. Posttreatment and 2-years posttreatment superimposed cephalometric tracings: A, superim-posed on sella-nasion plane at sella; B, superimposed on the posterior portion of the hard palate; C,superimposed on the mandibular plane at menton.

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734 Ru and Bai

removed. The patient and his family were satisfiedwith the results.

CONCLUSIONS

Autotransplantation with orthodontic treatmentcould be considered as a treatment alternative for animpacted tooth. Computerized tomography imaging isnecessary to develop a successful treatment plan.Extraction site preservation and fixation with titaniumprosthesis and a bioresorbable membrane on theautotransplanted canine during orthodontic treatmentwere helpful to prevent root resorption and ankylosis.

REFERENCES

1. Moss JP. The indications for the transplantation of maxillarycanines in the light of 100 cases. Br J Oral Surg 1975;12:268-74.

2. Hall GM, Reade PC. Root resorption associated with autotrans-planted maxillary canine teeth. Br J Oral Surg 1983;21:179-91.

3. Schmuth GP, Freisfeld OK, Schuller H. The application of comput-erized tomography (CT) in cases of impacted maxillary canines. EurJ Orthod 1992;14:296-301.

4. Ericson S, Kurol J. Radiographic examination of ectopicallyerupting maxillary canines. Am J Orthod Dentofacial Orthop1987;91:483-92.

5. Slagsvold O. Autotransplantation of premolars in cases of missinganterior teeth. Rep Congr Eur Orthod Soc 1970;66:473-85.

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8. Slagsvold O, Bjercke B. Applicability of autotransplantation incases of missing upper anterior teeth. Am J Orthod 1978;74:410-21.

9. Northway WM, Konigsberg S. Autogenic tooth transplantation.The “state of the art.” Am J Orthod 1980;77:146-62.

10. Andreasen JO, Paulsen HU, Yu Z, Bayer T, Schwartz O. A long-termstudy of 370 autotransplanted premolars: part II— tooth survivaland pulp healing subsequent to transplantation. Eur J Orthod1990;12:14-24.

11. Pogrel MA. Evaluation of over 400 autogenous tooth transplants. JOral Maxillofac Surg 1987;45:205-11.

12. Jonsson T, Sigurdsson TJ. Autotransplantation of premolarsto premolar sites. A long-term follow-up study of 40 consec-utive patients. Am J Orthod Dentofacial Orthop 2004;125:668-75.

13. Schwartz O, Bergmann P, Klausen B. Resorption of autotrans-planted teeth. A retrospective study of 291 transplantations overa period of 25 years. Int Endod J 1985;18:119-26:31.

14. Schwartz O, Bergmann P, Klausen B. Autotransplantation ofhuman teeth. A life-table analysis of prognostic factors. Int JOral Surg 1985;14:245-58.

15. Andreasen JO. Periodontal healing after replantation andautotransplantation of incisors in monkeys. Int J Oral Surg1981;10:54-61.

16. Andreasen JO. Analysis of pathogenesis and topography ofreplacement root resorption (ankylosis) after replantation of


mature permanent incisors in monkeys. Swed Dent J 1980;4:231-40.

17. Andreasen JO. Analysis of topography of surface and inflammatoryroot resorption after replantation of mature permanent incisors inmonkeys. Swed Dent J 1980;4:135-44.

18. Andreasen JO, Kristerson L. The effect of limited drying or removalof the periodontal ligament. Periodontal healing after replantationof mature permanent incisors in monkeys. Acta Odontol Scand1981;39:1-13.

19. Andreasen JO. Relationship between cell damage in the periodon-tal ligament after replantation and subsequent development ofroot resorption: a time-related study in monkeys. Acta OdontolScand 1981;39:15-25.

20. Andreasen JO. Relationship between surface and inflammatoryresorption and changes in the pulp after replantation of perma-nent incisors in monkeys. J Endod 1981;7:294-301.

21. Blomlof L, Lindskog S, Andersson L, Hedstrom KG,Hammarstrom L. Storage of experimentally avulsed teeth in milkprior to replantation. J Dent Res 1983;62:912-6.

22. Schwartz O, Andreasen FM, Andreasen JO. Effects of temperature,storage time and media on periodontal and pulpal healing afterreplantation of incisors in monkeys. Dent Traumatol 2002;18:190-5.

23. Cvek M. Treatment of non-vital permanent incisors with calciumhydroxide. I. Follow-up of periapical repair and apical closure ofimmature roots. Odontol Revy 1972;23:27-44.

24. Oswald RJ, Harrington GW, Van Hassel HJ. Replantation 1: the roleof the socket. J Endod 1980;6:479-84.

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26. Terheyden H, Gerhardt U, Konig J. Long-term follow-up of toothtransplantation from the functional and periodontal viewpoint.Fortschr Kiefer Gesichtschir 1995;40:84-7.

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29. Mine K, Kanno Z, Muramoto T, Soma K. Occlusal forces promoteperiodontal healing of transplanted teeth and prevent dentoalveo-lar ankylosis: an experimental study in rats. Angle Orthod 2005;75:637-44:SAME AS 25.

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Canine autotransplantation: Effect of extraction site ... · cally. After orthodontic treatment, a veneer could be placed on the canine to match the morphology of the contralateral

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