[A morphological study on the mandibular symphysis of cleft lip and palate, anterior crossbite and Angle Class I malocclusions].

Morphological characteristics of the mandibular symphysis among the cleft lip and palate, anterior crossbite and Angle Class I malocclusions were analyzed cephalometrically. 1. In the symphyseal thickness at pogonion, the significant differences among the three groups were not found. In the cleft group, the symphyseal thickness at point B was significantly narrower than that of the Class I group. 2. In the symphyseal height, the cleft group was larger than that of the crossbite group, while the crossbite group was the middle of the two groups. 3. In the symphyseal inclination, the cleft group was significantly large, compared to that of the crossbite and Class I groups. The symphyseal inclination of the cleft group was mostly the alveolar part of mandibular symphysis. 4. The chin formation was the absorption of the around of point B. The chin formation was appeared between the ages of A and B groups.