Oligodontia: a radiographic comparison of subjects with Down syndrome and normal subjects.

Panoramic radiographs and clinical records were used to investigate developmentally absent permanent teeth in 98 subjects with Down syndrome (trisomy-21). This retrospective study was based on the records and panoramic radiographs of subjects from approximately five years of age (the age at which mineralization of the permanent tooth germ could be identified) through to their most recent records. The time period covered by records ranged from 6 to 28 years. The majority of subjects with Down syndrome (63%) exhibited oligodontia, and many subjects were missing two or more teeth (53%). The most frequently absent teeth were the lower lateral incisors (23.3%), the upper second premolars (18.2%), the upper lateral incisors (16.5%), and the lower second premolars (15.3%). In general, the distribution of the developmentally absent teeth was similar for teeth in homologous positions (i.e., left and right canines, etc.) on either side of the midline or between the maxilla and the mandible. The only significant exceptions to this pattern were seen with the central incisors and the second molar. This study's findings suggest a high risk of oligodontia in subjects with Down syndrome.