Survey of anomalies in primary teeth and their correlation with the permanent dentition.

The purpose of the study was to investigate primary and permanent tooth anomalies of 5-year-old children in Taranaki; 1,680 children were examined by school dental therapists, and the presence of hypodontia, hyperdontia, and double teeth recorded. Panoramic radiographs were taken of those children with anomalies of the primary teeth. Anomalies of the primary teeth were detected in 23 children (1.4 percent). Six children (3 boys and 3 girls) had hypodontia, 3 children (2 boys and 1 girl) had a supernumerary tooth, and 14 children (9 boys and 5 girls) had double teeth. Six of the affected teeth (in 4 boys and 2 girls) were diagnosed as fusion, and 8 (5 boys and 3 girls) as gemination. The panoramic radiographs of the 23 children with anomalies of the primary teeth revealed that 14 (60.9 percent) also had anomalies of the succedaneous permanent teeth. Children with hypodontia in the primary dentition all had corresponding permanent teeth missing. In all but three children, only one tooth was involved. Nineteen of the 30 primary teeth (63 percent) and 12 of the 15 permanent teeth (80 percent) affected by hypodontia, gemination, or fusion were lateral incisors. For each type of anomaly, boys were affected more often than girls. The results of the study confirm that, when there is hypodontia, hyperdontia, gemination, or fusion of teeth in the primary dentition, there is an increased likelihood of anomalies of the succedaneous permanent teeth. Because of this close relationship between the dentitions, early identification of anomalies of the primary teeth can allow the dentist to investigate further and plan for treatment at the appropriate time.