Associations of some variables to tooth formation in children with isolated cleft palate.

The timing of tooth formation in 251 children, affected with isolated cleft palate without syndromes or other concomitant visceral anomalies (CP), was evaluated from orthopantomograms. The age range was 6-12 yr. The formation of the permanent teeth was delayed approximately 0.7 yr in CP children compared with the data on the non-cleft reference group. There were no differences in sex distribution between the CP group and the non-cleft reference group and between the CP subgroups. No significant differences in tooth formation could be detected between the subgroups; with and without positive family history of clefts, with and without conical elevation of the lower lip, and between the subgroups of submucous, partial and complete cleft of the palate. The presence of hypodontia promoted the delay significantly and the delay increased with increasing number of missing teeth per child. In the older age group of 9-12 yr, the delay was significantly longer (1.1 yr) than in the younger age group of 6-9 yr (0.6 yr). The present findings of tooth formation support the hypothesis that the genetic component in the multifactorial situation does not act directly in producing the malformation itself, but indirectly, through a reduction in buffering. Furthermore, at least some of the sporadic cases have a partly genetic etiology.