Abstract
Children with supernumerary teeth are not rare. Although there are a number of reports concerning two supernumerary teeth, reports on eruption of more than three supernumerary teeth on the same site are rare. The incidence rates of permanent fused teeth are lower than those of deciduous fused teeth, estimated at 0.05 to 0.35%. The rates are approximately one tenth as low as the rates of deciduous fused teeth. A fused normal maxillary central incisor among the supernumerary teeth is in particular extremely rare in Japan.
We had an opportunity to treat a 9 years 4 months boy who visited our Department of Pediatric Dentistry, Suidobashi Hospital of Tokyo Dental College, complaining of supernumerary teeth. On the first examination, he appeared to have developed two supernumerary teeth on the median maxilla and a fused tooth consisting of another supernumerary tooth and the right maxillary central incisor to form twin teeth.
The general condition of the patient showed no abnormalities. A simple corn type of a supernumerary tooth had erupted in the left maxillary central incisor region, and another supernumerary tooth had erupted on the palate site of the right maxillary central incisor with only its caput erupting. The shape of the right central incisor appeared as fused tooth consisting of a supernumerary tooth and a labial portion of the incisor. Dental X-rays found that the simple corn shaped fused tooth had only one tooth root and that the left maxillary central incisor had not erupted. The right maxillary central incisor had a simple corn or double corn shaped appearance, indicating that the twin teeth were formed by the supernumerary tooth and the incisor. The X-rays also revealed that the twin teeth had a branched dental pulp on its crown with a common pulp on its root.
