Condylar translation, skeletal morphology, and form of glenoid fossa in skeletal Class III malocclusion

Comparison with Angle Class I malocclusion and normal occlusion

Abstract

To characterize the relationship between jaw movements and skeletal morphology, the amount of condylar translation and morphology of glenoid fossa were investigated using the subjects with skeletal Class III malocclusion, Angle Class I malocclusion, and acceptable normal occlusion. Standardized lateral oblique transcranial projection radiography of temporomandibular joint and lateral cephalograms were taken in this study. Based on the lateral oblique transcranial projection radiography, restricted condylar translation at maximal mouth opening was found in 20 of 48 patients with skeletal Class III (30 of 96 joints), 1 of 30 patients with Angle Class I malocclusion (2 of 60 joints), and none of 30 subjects with an acceptable normal occlusion. In addition, it was shown that skeletal Class III subjects had deeper glenoid fossa and steeper posterior slope of the glenoid eminences than those of the subjects with Angle Class I malocclusion and normal occlusion.
Although comparing the skeletal morphology between skeletal Class ID subjects with and without restricted condylar translation, the former showed larger gonial angle, mandibular plane angle (∠SN-Mp) and palatal plane to functional occlusal plane (∠Pp-FOC), there was no significant difference in the amount of condylar translation and form of the glenoid fossa. These results suggested that facial morphology could be related with condylar translation.