Relationships among Occlusal Force, Condylar Surface Area, and Facial Patterns

Abstract

The interactions between orofacial muscles and skeletal patterns are widely recognized as significant factors in craniofacial growth. Many studies have suggested that the vertical facial growth pattern correlates with occlusal forces and the activity of masticatory muscles. In particular, it has been suggested that occlusal forces produced by masticatory muscles are converted into physiological stress at the condyle in the form of functional strain. In such circumstances, the dimensions and morphology of the condyle ought to be affected. The aim of this study is to test the hypothesis that low-angle subjects with larger occlusal forces tend to have mandibular condyles with a larger surface area than high-angle subjects. Cone-beam computed tomographic scans were obtained from 14 Japanese adult subjects (17 to 33 years old, 7 high angle and 7 low angle) at 60 kV and 10 mA. Occlusal force was measured by pressure-indicating fi lms, and the surface area of the condyle was calculated from axial CT data. The correlation between occlusal conditions and the surface area of condyles was compared between the two facial groups. We found that the low-angle group had a signifi cantly larger surface area and volume of condyles than the high-angle group and that there was a positive correlation between occlusal forces and condylar surface area. Our fi ndings demonstrate that occlusal force is one of the important factors that affect the mechanical environment of the condyle.