Bilateral Fusion of Mandibular Second Molars with Supernumerary Teeth: Case Report

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Braz Dent J (2002) 13(2): 137-141

Bilateral fusion

ISSN 0103-6440

Bilateral Fusion of Mandibular Second Molars with
Supernumerary Teeth: Case Report
Eduardo NUNES 1
Ivaldo Gomes de MORAES 2
Paulo Márcio de Oliveira NOVAES 3
Simone Maria Galvão de SOUSA4
1 Department

of Endodontics, Pontificial Catholic University, Belo Horizonte, MG, Brazil

2 Department of Endodontics, Bauru Dental School, Bauru, SP, Brazil 4 Department

3 Private Endodontic Practice, Belo Horizonte, MG, Brazil
of Oral Pathology, Faculty of Dentistry, University of Sacred Heart, Bauru, SP, Brazil

Fusion is a developmental anomaly characterized by the union of two adjacent teeth. In this article we report a rare case of bilateral fusion of permanent mandibular second molars with supernumerary teeth. The rarity with which this entity appears, along with its complex characteristics, often make it difficult to treat. The endodontic management of one tooth is described, as well as the successful treatment of a periradicular lesion.

Key Words: dental anomaly, fusion, supernumerary tooth, endodontic treatment.

Fusion is commonly identified as the union of
two distinct dental sprouts which occurs in any stage of
the dental organ. They are joined by the dentine; pulp
chambers and canals may be linked or separated depending on the developmental stage when the union occurs. This process involves epithelial and mesenchymal germ layers resulting in irregular tooth morphology (1). Moreover, the number of teeth in the dental arch is

less than normal. A review of the literature reveals great
difficulty in correctly differentiating fusion and gemination. For a differential diagnosis between these anomalies, the dentist must carry out a highly judicious
radiographic and clinical examination.
The aetiology of fusion is still unknown, but the
influence of pressure or physical forces producing close
contact between two developing teeth has been reported as one possible cause (2). Genetic predisposition and racial differences have also been reported as contributing factors. This anatomic irregularity occurs more often in

the deciduous than in the permanent dentition. Only a

few cases of fusion involving molar and premolar teeth
have been reported (3-5) whereas, in both dentitions,
the prevalence is higher in the anterior region (6-9).
Cases of bilateral fusion are less frequent than unilateral fusion (6). Turell and Zmener (3) described a case of fusion involving a mandibular third molar and fourth
molar (distomolar). Unfortunately, most of these fusions require surgical removal because of their abnormal morphology and excessive mesiodistal width, which
cause problems with spacing, alignment and function
(6,8). In the anterior region this anomaly also causes an
unpleasant aesthetic tooth shape due to the irregular
morphology. These teeth also tend to be greatly predisposed to caries and periodontal disease and, in some cases, endodontic treatment is very complicated (7,10).
Fusion can occur between teeth of the same
dentition or mixed dentitions, and between normal and
supernumerary teeth (3,7-9,11,12). In these cases, the
number of teeth in the dental arch is also normal and
differentiation from gemination is clinically difficult or
impossible. A diagnostic consideration, but not a set
rule, is that supernumerary teeth are often slightly
aberrant and present a cone-shaped clinical appear-

Correspondence: Profa. Dra. Simone Maria Galvão de Sousa, Disciplina de Patologia Bucal, Faculdade de Odontologia, USC, Rua Irmã Arminda, 10-50, 17044-160 Bauru, SP, Brasil. Tel: +55-14-235-7144. Fax: +55-14-227-6581. e-mail:

Braz Dent J 13(2) 2002


E. Nunes et al.

ance. Thus, fusion between a supernumerary normal
tooth will generally show differences in the two halves
of the joined crown. However, in gemination cases the
two halves of the joined crown are commonly mirror...
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