The effects of material mechanical properties on three-dimensional nonlinear simulation of human temporomandibular joint forces

Objective: To compare and analyze the effects of the material mechanical properties of the bone structure and disc within the temporomandibular joint （TMJ） on three-dimensional nonlinear simulation of human TMJ forces. Methods: Combining spiral CT scanning technology with three-dimensional finite element method, together with Auto CAD software, three-dimensional nonlinear finite element models were developed, from in vivo, for comparison with the changes of the stress within the TMJ in the conditions of various material mechanical constants of the mandible, articular fossa and disc.Results: The isotropy and anisotropy of the bone tissue made some definite influences for the stress distribution of the TMJ bone structure. The material anisotropy increased their von Mises stresses, especially in the condyle and the anterior and medial regions named as the function loading in the joint. Meanwhile, the stresses in other positions of the bone structure and in the disc showed only a mild change. Various linear and nonlinear elastic moduli of the disc had no effect on the von Mises stress distribution in the TMJ during centric occlusion. Conclusion: The condyle and the anterior and medial regions in the TMJ may be the stress sensitive positions influenced easily by the change of material mechanical properties. The disc possesses a strong action on dispersing and buffering the force within the joint. The knowledge of the biological tissue mechanical properties is the foundation and assurance to reflect and simulate the mechanical environment in the life body more really and rationally.