A 3D Finite Element Model of Mastication Muscles to Study the Jaw Movement for TMJ Prosthesis Performance Evaluation

In this study, a 3D finite element analysis was performed in order to investigate the movement of lower jaw of an intact mandible in comparison with the mandible having had a TMJ prosthesis replacement surgery. An artificial TMJ was replaced the left condyle of the mandible and the output was explored. The results revealed that the movement of the jaw is congruent with intact model. The geometry of the model was obtained through CT scan images of a healthy skull and seven bundles of muscle fibers were inserted in their appropriate positions following the anatomical data. Finally building the finite element model, the jaw movement was simulated under different muscle activations. In the next step, the TMJ prosthesis was implanted in its proper position and the same simulations were carried out. The results show that both models producing same range of movements under similar muscle activation. Moreover, the replacement of the condyle by TMJ prosthesis manifests that design of the TMJ implant produces kinematical resemblances with real situation, but the resulting stress distribution is completely different especially around the fastening screws. Due to muscle removal by surgery operation the model can predict the effect of muscle force redistribution for producing the same range of motion.