Bilateral fusion of mandibular second molars with supernumerary teeth: case report

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. 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. Genetic predisposition and racial differences have also been reported as contributing factors.