Craniofacial characteristics of subjects with normal and postnormal occlusions--a longitudinal study.

Lateral skull radiographs of 85 growth study children taken at 5, 10, and 15 years of age, with normal/Class I occlusion (normal) and Class II, Division 1/Division 2 occlusion (postnormal) were digitized and analyzed by means of stepwise discriminant analysis. The cranial base angle proved to be the best discriminator between the two groups, the value at age 5 years being an accurate predictor of the occlusal type at 15 years in 73% of subjects. Although the majority of subjects grew predictably, their craniofacial characteristics being compatible with their ultimate occlusal type, 17% showed a growth trend from postnormal to normal and 9% a trend from normal to postnormal. By 15 years of age, only 8% of subjects possessed an occlusion at variance with their facial type. The cranial base angle is suggested as the fundamental determinant of jaw relation, but in some subjects this may be compensated by differential jaw growth manifested by a change in angle ANB.