Muscular and articular forces exerted on the human mandible

摘要

A joint prosthesis design takes into account data characterizing the natural biomechanics. To characterize the temporomandibular joint (TMJ) the approach had to be both kin-ematic (geometry, displacements) and quasi-static (forces, strains, stresses), the two being comple-mentary. This paper presents a 3D method quantifying and analyzing the muscle and the joint forces exerted on the mandible under loadings. The experimental protocol, the hypothesis, the elaboration and the resolution of the equation system that traduces the mandible equilibrium, are described and then applied using the data of four volunteers. Dissections made it possible to describe the contacts between the mandible condyles and the temporal bone and as well the jaw closing muscle insertions. The directions of the muscular forces were thus determined in a morphological coordinate system. A sensor was designed to simulate the bite force between two teeth, successively between two inci-sors, two premolars and then two molars. MRI and electromyography results permitted, in vivo, to evaluate the magnitudes of six jaws closing muscle forces for each side of the face. The resolution of the equation system written to calculate the forces transmitted through the articular contacts was computer-assisted. 1 INTRODUCTION