Congenitally missing second premolars in cleft lip and cleft palate children.

Panoramic and periapical radiographs of 278 patients with cleft lip, cleft palate, or both (158 males and 120 females), age 5 to 18 years, were examined to determine the frequency of missing second premolars and the possible association between the cleft side and the side from which the premolar was absent. The prevalence (18%) of missing premolars found in this study is significantly higher than is found in the general population. A considerably higher incidence of missing second premolars was found in the maxilla compared with the mandible both for unilateral and bilateral missing teeth. The second premolar was absent more frequently on the left than on the right side, both in males and females and in both jaws. Interestingly but consistent with our previous reporting, this corresponded to the side where clefts occurred more often. The cause of the higher prevalence of left-sided clefts and missing second premolars in human beings is not known at the present time.