Analysis of orthodontic anomalies in mentally retarded developmentally disabled (MRDD) persons.

For this epidemiologic study, 458 individuals with mental retardation and developmental disability (MRDD), from 6 to 87 years old, from the Lower Hudson Valley region of New York, were evaluated for the occurrence of orthodontic anomalies. High occurrence of both anomalies of intermaxillary relation, as determined by Angle's classification, and the anomalies of occlusion were found in these individuals when compared with the general population. An increased incidence of both acquired (i.