Biomechanical analysis of stress distribution in the human temporomandibular-joint

The positions of the head of the mandible, of the articular disc and the ou tline of the temporal surface are digitized from sagittal MRI-scans of the temporomandibular joint of a 32-year-old subject in 5 different positions o f occlusion. The stress distribution in the joint is calculated on the basi s of these data. For each position of the condyle, the momentary center of rotation in the head of the mandible and the tangent attached to the tempor al surface are determined. The line connecting these two points indicates t he direction of the resulting compressive force. Furthermore, the extension of the area available to the force transmission is estimated. By means of these parameters the stress distribution is calculated independently from t he position. The analyses show that the temporomandibular joint is slightly eccentrically loaded in all positions. The increase of the stresses is in all cases oriented caudo-ventrally. The results are verified in an anatomic al specimen of the articular tuberculum. The trabecular structures as well as the subchondral bone-lamella of the articular tuberculum are functionall y adapted to the analyzed stress situations.