Aspects of mandibular morphology, with specific reference to the antegonial notch and the curve of Spee.

The purpose of this investigation was to determine whether particular metrical traits of the mandibular antegonial notches are associated with specific mandibular growth patterns, and also with the mean depth of the curve of Spee. Thirty pre-treatment lateral cephalometric radiographs belonging to a randomly selected group of patients treated in the orthodontic clinic at the SUNY at Buffalo were digitized. The surface areas of the mandibular antegonial notches, as well as some sagittal facial dimensions were measured on each radiograph. The curve of Spee was measured directly from the pre-treatment mandibular study cast of each patient included in this study. An analysis of variance showed no statistically significant difference (p < 0.01) between the measurements recorded by the two examiners who conducted this study. The results of this study showed a statistically significant positive correlation between the surface areas of the antegonial notches and the lower anterior facial heights (r = 0.87, P < 0.001). At the same time a statistically significant negative correlation was found between the surface areas of the antegonial notches and the lengths of the mandibular bodies (r = -0.9, P < 0.001). A significant negative statistical relationship was shown to exist between the lower anterior facial heights and the lengths of the corresponding mandibular bodies, and also between the depths of the curves of Spee and the surface area of the respective antegonial notches (r = -0.85, P < 0.002). The results of this study indicate that an increase in the areas of the antegonial notches is associated with a tendency for greater vertical growth of the mandible. The results further suggest that the depth of the curve of Spee and the length of the mandibular body are decreased when there is an increase in the surface areas of the antegonial notches.