Length of the cleft in relation to the incidence of hypodontia of the second premolar and to inheritance of cleft lip and palate in children with isolated cleft palate.

We studied severity of the isolated cleft palate expressed as the length of the cleft in relation to hypodontia in the second premolar regions and known inheritance of any type of cleft lip and palate. The material consisted of 47 children at 10 years of age born with non-syndromic isolated cleft palate of varying extent, who all had hypodontia of at least one second premolar, and had panoramic radiographs taken at 10 years of age. Information about length of cleft and inheritance of cleft lip and palate was collected from surgical files initiated at birth. The higher the number of missing second premolars, the more extended was the length of the cleft. More children had hypodontia of the second premolar in the mandible than in the maxilla. The family history had little influence on the length of the cleft.