[A case of a so-called congenital tooth appeared in maxilla].

: The congenital teeth are not only classified by Massler et al. as a natal tooth that has erupted at birth and a neonatal tooth that erupts at neonatal period, but also divided into a normal deciduous tooth and a supernumerary tooth. The congenital teeth are mostly found in the mandibular anterior region, but extremely rare in other regions. The authors met a rare case, that had a so-called congenital tooth in the maxillary anterior region, which was a supernumerary and fused tooth. The case was a boy patient, 4 months of age, who visited the pedodontic clinic, of Ohu University Dental Hospital, with the complaint of ruber and swelling of the maxillary anterior gum pad, October 17th in 1986. By oral inspection of the dental radiogram and his past history, the authors found a odontoid material in the swelled gum pad and diagnosed it as a so-called congenital and supernumerary tooth. The tooth was extracted. The extracted tooth was investigated histopathologically. It had the v-shaped incisula at the middle of its edge, and seemed as if two teeth had coalesced. The serial preparations by the labio-lingual section showed no partition, such cementum as to divide the enamel, the dentin and the pulp near the incisula. Therefore it was diagnosed as fused tooth correctly. In the labial surface of the root formed about a third root length, the thickness of the cellular cementum was observed. It was considered as a physiological reaction to no support of the alveolar bone and to the excess mobility of the tooth. The prognosis after its extraction was good, and all normal deciduous incisors appeared in his mouth, 7 month later.