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Fusion of Central Incisors with Supernumerary Teeth:A 10-year Follow-up of Multidisciplinary TreatmentNelly Steinbock, DMD,*Ronald Wigler, DMD,*Arieh Y. Kaufman, DMD,*Shaul Lin, DMD,*

Imad Abu-El Naaj, DMD, and Dror Aizenbud, DMD, MSc

Abstract

Introduction:Macrodontia of anterior teeth may occuras an isolatedcondition or as a result of fusion or gemina-tion andmay causeclinical problems such as tooth crowd-ing and esthetic problems. Preliminary planning andcareful management are often required by a dentalteam comprising an orthodontist, an endodontist, a pros-thodontist, and an oral surgeon. A multidisciplinary treat-ment approach in a case with fused teeth is presented.Methods:A 9-year-old girl presented with macrodontia

of a leftmaxillary central incisor. The patient was referredto the orthodontic department because of a large centralincisor as a result of fusion with an unspecific supernu-merary tooth. The surgical procedure included sectioningoff the mesial segment as far as possible, both apicallyand subgingivally, and extracting 1 of the fused supernu-merary teeth. During the sectioning procedure, the pulpof the remaining tooth was exposed at the middle thirdof the root. Direct pulp capping was performed by anendodontist using mineral trioxide aggregate. Twelveweeks later, orthodontic treatment was commenced,and finally after a 26-month orthodontic treatmentperiod, the central incisors crown was restored using

composite material.Results: A 10-year clinical andradio-graphic follow-up revealed that the remaining resectedcentral incisor kept its vitality, and the patient waspleased with the esthetic result. Conclusions: Properinterdisciplinary treatment planning of complicated casessuch as anomalous teeth,which involve fusion to a super-numerary tooth, may lead to minimal invasive conserva-tive procedures that maintain tooth vitality and result in apleasing esthetic result.(J Endod 2014;40:10201024)

Key WordsCentral incisor, mineral trioxide aggregate, orthodontic,tooth sectioning

Occasionally, orthodontists and general dentistsencounter patients withmacrodontiaof anterior teeth as a result of fusion or gemination of maxillary incisors. It isextremely difficult to restore the natural look of such a wide tooth. Furthermore, if amacrodontic tooth is left in the dental arch, it may severely compromise the eruptionof adjacent teeth causing occlusal alteration. Fusion and gemination are anomalieswith close similarity inherited by different etiologies(1). Fusion is a double toothresulting from the union of 2 adjacent tooth germs (2). According to Regezi et al(3), it may involve the entire length of the teeth or the roots only, in which casecementum and dentin are shared. Root canals also may be separated or shared, which

may lead to a reduced number of teeth or may occur between a normal and supernu-merary tooth. Concrescence is a form of fusion in which the adjacent, already formedteeth are joined by cementum, which may take place even before the eruption of teeth.

Gemination is a disturbance during odontogenesis in which partial cleavage of thetooth germ occurs and results in a tooth that has a double or twin crown, it is usuallynot completelyseparated, and a common root and pulp space is shared (2). Geminationis an aborted attempt of a tooth bud to divide, and unlike fusion, the root and root canalremain undivided. The typical result is partial cleavage with the appearance of 2 crownsthat share the same root canal(3). The prevalence of these anomalies is reported to beless than 1%, occurring predominantly in incisors and canines with apparent equaldistribution between the 2 jaws, and more common in deciduous teeth (4).

Macrodontiaof anterior teeth, whether caused by fusion or gemination,creates prob-lems of crowding and esthetics. The absence of vertical to horizontal crown size harmony

(referred to as the golden proportions) is disturbing and esthetically unacceptable.Orthodontists treatment planning requires special attention, and such planning shouldbe performed by a multidisciplinary consultation team comprising endodontists, prostho-dontists, and oral surgeons to determine the best treatment approachwith the most accept-able outcome. When the treatment includes sectioning off the tooth, part of it may be leftintact. In this case, a possible communication between the pulp chambers and/or rootcanal systems should be considered, and an endodontic specialist should be involved inthe process. Proper treatment by an endodontic specialist may include pulp capping usingmineral trioxide aggregate (MTA) and avoidance of a complete root canal procedure.

Preserving the dental pulp or part of it in a healthy state is important in treatingteeth with exposed vital pulp. MTAis a bioactive biocompatible material capable of seal-ing the pathways of communication between the root canal system and the external sur-faces of the teeth and creating an ideal environment for healing(5, 6). When placed in

direct contact with pulp tissue, it encourages formation of a calcified bridge, thuscreating both a mechanical and biologic seal(6).

From the *Departments of Endodontics and Dental Traumatology, School of Graduate Dentistry, Rambam Health Care Campus, Haifa Israel; and Departments ofOral and Maxillofacial Surgery and Orthodontic and Cranofacial, Rambam Health Care Campus, Technion Faculty of Medicine, Haifa, Israel.

Addressrequestsfor reprints to Dr DrorAizenbud,Orthodontic and Craniofacial Department, School of Graduate Dentistry, Rambam Health Care Campus,Haifa,P.O.Box 9602, 31096, Israel. E-mail address:aizenbud@ortho.co.il0099-2399/$ - see front matter

Copyright 2014 American Association of Endodontists.http://dx.doi.org/10.1016/j.joen.2013.12.004

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mailto:aizenbud@ortho.co.ilhttp://dx.doi.org/10.1016/j.joen.2013.12.004http://dx.doi.org/10.1016/j.joen.2013.12.004mailto:aizenbud@ortho.co.il

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The aim of this case report was to describe a 10-year outcome of acombined treatment of a fused maxillary incisor by means of an ortho-donticendodonticprosthodonticoral surgerymanagement protocol.

Case ReportA 9-year-old girl was referred for treatment in the year of 2002

while presenting with macrodontia of a left maxillary central incisor

because of esthetic complaints (Fig. 1A). The remaining primary andpermanentteethwereof normal size andshape, and thenumber of teethwas not reduced. Family and medical history were noncontributory.

Clinically, the maxillary left central incisor and an unspecificsupernumerary tooth appeared as fused teeth at the cervical third ofthe crowns, whereas separated roots could be diagnosed in the pano-ramic and periapical views (Fig. 1Band C[seearrows]). This may alsobe considered gemination with a deep vertical groove dividing the toothin the coronal two thirds to 2 conical-shaped parts wherein the distalsegment was wider. The total mesiodistal width of the fused left crownwas 15 mm compared with 10 mm of the right (normal) central incisorcrown. The resulting dental crowding of the maxillary incisor regioncaused a shifting of the fused distal segment toward the buccal (disto-buccalrotation) compared with themesial segment (Fig. 1). The vitality

test was conclusive, showing a normal response to the cold test (EndoIce; Hygenic, Akron, OH).

Radiographically, 2 distinct roots united by the cementum wereapparent (Fig. 1BandC), and a diagnosis of normal pulp with normalapical tissues and fusion of the left central incisor with an unspecificsupernumerary tooth was established by means of clinical and radio-graphic examination.

The surgical treatment plan included sectioning off the mesialsegment as far as possible, both apically and subgingivally, in orderto extract the mesial (small) fused tooth. The procedure was per-formed under local anesthesia. No premedication was required. Nospecial preparation of the oral cavity was implemented. A full-thickness buccal and palatal gingival mucoperiosteal envelope flapwas performed (Fig. 2A). A sharp osteotome was placed at the incisalnotch groove site aligned obliquely (distally) to the long axis of the

root in order to section the crown and part of the root. A sharp tapwith a mallet sectioned off the undesirable part of the oversized crown(fused supernumerary). The plane of the separation was terminatedsubgingivally as preoperatively desired and directed by angling theosteotome.

During the sectioning, a 4-mm-wide oval hole was observed atthe midthird of the root, and the pulp was observed through it.The hole was filled with MTA using a dental spatula and burnishedon the root surface to facilitate direct pulp capping (Fig. 2B). Beforeflap suturing, nonrotary bone contouring was performed to removesharp margins and to enable tight covering of the original gingival tis-sue over the MTA site.

After a 12-week asymptomatic follow-up period (Fig. 3A), the or-thodontic treatment was initiated. The patient was diagnosed with skel-

etal class II and an Angle class II division I malocclusion. The pattern ofjaw growth was normal, and a slightly constricted maxilla was diag-nosed; however, no crossbite was recorded. Maxillary incisor dentalcrowding was noted. Orthodontic treatment extended over a periodof 3.5 years (Fig. 3C). After achieving all orthodontic goals, compositerestoration was applied to the sectioned maxillary central incisor inorder to achieve final esthetics by mimicking the right central incisor

Figure 1. The preoperative macrodontic maxillary left central incisor fused to an unspecific supernumerary tooth. (A) The intraoral frontal view. (B) The pano-ramic radiograph view. (C) The periapical radiograph view. The arrowspoint to the separate root.

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(Fig. 3C). Periapical radiographs that were taken right before (Fig. 3B)and immediately after orthodontic treatment (Fig. 3D) revealed a goodhealing process of the sectioned incisor.

Follow-upFollow-up appointments included standard orthodontic-

restorative-endodontic clinical examination and vitality tests at 6-monthintervals. A periapical radiograph was annually performed during thefirst 3 years. After 3 years, because of relocation, the patient declinedrecall and reappeared 10 years after surgery.

Ten years postoperatively, the tooth preserved its vitality. The pulpwas evaluated by means of lack of symptoms, vital signs by pulp testing,and the normal periapical area as determined through the radiographs.The composite restoration was intact with no clinical or radiographicsigns of secondary carries, and replacement was recommendedbecause of discoloration (Fig. 4AC).

DiscussionThe presence of an abnormally sized anterior tooth with a funny-

shaped crown presents a challenge that is difficult to treat by conventional

Figure 2. The surgical procedure. (A) A full-thickness buccal and palatal gingival mucoperiosteal envelope flap raised, facilitating sectioning off of the undesirablepart of the oversized crown (fused supernumerary tooth). (B) Periapical radiograph views of the tooth after removal of the extra tooth material (supernumerary

tooth) and the application of MTA performing direct pulp capping.

Figure 3. Pre- and post-orthodontic treatment stage. (A) The preorthodontic intraoral frontal view of the asymptomatic maxillary left central incisor taken aftersectioning off the fused supernumerary teeth and MTA sealing. (B) The preorthodontic periapical radiograph view. (C) The intraoral frontal view at the end of theorthodontic treatment and after performance of composite restoration to achieve final esthetics by mimicking the dimensions of the right maxillary central incisorscrown. (D) The postorthodontic periapical radiograph view.

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orthodontic treatment planning. Matching maxillary and mandibularmidlines may not be possible, and ideal overbite and overjet measure-ments may be compromised.

Clinically, it is difficult, if not impossible, to differentiate fusionfrom gemination when supernumerary teeth are involved. However,

the aim of the treatment and the protocol are the same. In this case,a full-thickness buccal and palatal gingival mucoperiosteal envelopeflap was performed under local anesthesia containing lidocaine +1:100,000 epinephrine, facilitating sectioning off the root and part ofthe crown and removal of the extra tooth material (supernumerarytooth) by an osteotome. The resulting wide whole in the root areaincluded pulp exposure that was sealed with MTA, thus forming directpulp capping. Consequently, a normal dimension of the maxillarycentral incisor crown was restored, enabling a normal class I occlusionand better esthetics.

The communication between the pulp chambers and/or root canalsystems of fused or geminated teeth is a known fact(7, 8). Treatmentplanning for surgical exposure should be considered when performing

sectioning of the malformed tooth. Although root canal treatment isroutinely considered in these cases(4), it may be avoided if the exposedsite is not infected and is limited in size by performing pulp capping usingMTA. With this method, remainingcoronal andradicular pulp tissue pres-ervation is expected. MTA may induce the healing process of the exposedpulp tissue including reorganization of the soft tissue, differentiation ofodontoblast-like cells from subodontoblast cells, and repair of theexposed dentine tissue with reparative dentine bridge formation(6).

According to Parirokh and Torabinejad(6), MTA is a promisingmaterial for preserving pulp tissue when used as capping material afterpartial or total pulpotomy. The study by Pitt Ford et al(5)on monkeysshowed that most of the pulps that were capped with MTA were free ofinflammation, and all of them showed formation of a calcified bridgeafter 5 months. In the study by Salako et al(9)with rats, MTA proved

to be the ideal agent in terms of dentin bridge formation and preservingnormal pulpal architecture.

The radiographs taken throughout the treatment and follow-upperiod show a reduction in the thickness of the layer of MTA(Figs.2B, 3D,and 4C). It is knownthat MTApossesses dissolution char-

acteristics(10). The bioactivity of MTA is explained by the release of Caand the resultant formation of hydroxyapatite. This suggests that MTAcould be used to repair procedural accidents as well as intentionalpulp capping as described in the present case report. The vicinity ofthe location of theprocedure to the gingival margincouldbe elaboratedto the extended MTA dissolution as marginal gingivitis, which is a com-mon phenomenon in orthodontic cases and could cause pH reduction,which affects MTA solubility(11).

A decision must be made about the treatment options and eventualrestoration of the anterior segment. Extraction is considered a poor so-lutionduring childhoodand adolescence because an implant is notrec-ommendeduntil skeletalmaturation (12). Alternative treatment optionsmight be closure of the edentulous space and substitution of the ipsilat-

eral lateral incisor as the central incisor or autotransplantation. How-ever, the patient must have an arch-length deficiency and dental archasymmetry, so that a premolar from a posterior quadrant can be trans-planted to the edentulous site.

Generally, teeth surrounded by healthy periodontal tissues yield avery high longevity rate (over 50 years in up to 99.5%)(13). Likewise,periodontally compromised yet treated and maintained teeth andendodonticallycompromisedbut successfully treatednonvital teeth yieldhigh survival rates. Currently, oral implant survival rates (82%94%) donot surpass the longevity of even compromised but successfully treatednatural teeth.

Because of these difficulties and the high longevity of treated andmaintained teeth, dentists should avoid extraction whenever possible.Reduction of the over plus crown size in order to achieve a normal

Figure 4. Ten-year follow-up revealing an asymptomatic vital left maxillary central incisor, a stable anterior and posterior occlusal relationship, and estheticallypleasing dental and facial appearance of the original composite restoration. (A) The intraoral frontal view. (B) The panoramic radiograph view. (C) The periapicalradiograph view.

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crown is a preferable anda conservativetreatment optionin macrodon-tic tooth cases. If the pulp is exposed during sectioning of the crown,pulp capping should be performed. If the pulp is injured, root canaltreatment should be performed.

ConclusionSuccessful orthodontic-endodontic-surgical treatment of a central

incisor fused witha supernumerarytooth was presented. Althoughthere

was communication between parts of the pulp chambers, root canaltreatment was avoided because of the vital pulp therapy that was per-formed. Proper clinical and radiographic multidisciplinary examina-tion, correct diagnosis, and treatment planning are key features ofsuccessful vital treatment. The novelty of this case is the multidisci-plinary modern approach toward a macrodontia that was taken, whichresulted in keeping the tooth vital as documented in the long-termfollow-up period of 10 years.

AcknowledgmentsThe authors deny any conflicts of interest related to this study.

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6. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature

reviewpart III: clinical applications, drawbacks, and mechanism of action.J Endod 2010;36:40013.7. Libfeld H, Stabholz A, Friedman S. Endodontic therapy of bilaterally geminated per-

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10. Bozeman TB, Lemon RR, Eleazer PD. Elemental analysis of crystal precipitate fromgray and white MTA. J Endod 2006;32:4258.

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