[A supernumerary primary tooth inducing impaction of primary incisor: a case report].

A case of a primary supernumerary tooth in a 18 month old girl was reported. 1. The supernumerary tooth was located in the maxillary incisor area. 2. The maxillary left primary central incisor and the primary supernumerary tooth were impacted. 3. The clinical and radiographic findings indicated that the primary tooth in the mesial position was the supernumerary tooth, and therefore it was removed. 4. Three days after extraction of the mesiodens, the left primary central incisor erupted. The tooth completely erupted in two months. 5. The radiographic examination showed no supernumerary succedenous teeth.