Pattern of agenesis in the primary dentition: a radiographic study of 193 cases

The purpose of this study was to examine radiographs of a large sample of children who had congenital absence of primary teeth and to determine the number and distribution of the missing teeth. Radiographs collected within the Danish Municipal Child Oral Health Care System were available of 193 children, all of whom had congenital absence of one or more primary teeth but no other abnormalities in the jaws or dentition. More than half of the children (54.9%) had agenesis of only one primary tooth, and 7.8% of more than two primary teeth. Agenesis was found twice as frequently in the maxillary lateral incisor region (119 children) than in the mandibular lateral incisor region (53 children). Congenital absence of primary molars, canines and maxillary central incisors was extremely rare. However, agenesis of one maxillary primary central incisor was found in two cases. A follow-up study will compare the agenesis patterns recorded with the pattern of agenesis in the permanent dentition of the same group of children.