FEM and BEM Analysis of a Human Mandible with Added Temporomandibular Joints

Mathematical modelling of human mandible and its temporomandibular joints (TMJs) is one of the most important steps for developing a powerful forecasting tool to analyse the stress/strain behaviour of a human masticatory system under occlusal loads. In this work the structural behaviour of a mandible with articular discs, undergoing a unilateral occlusion, is numerically analysed by means of both Finite Element Method (FEM) and Boundary Element Method (BEM). The mandible is considered as completely edentulous and its anisotropic and non-homogeneous bone material behaviour is modelled. The material behaviour of the articular discs was assumed to be either elastic or hyper-elastic. The loads applied to the mandible are related to the active muscle groups during a unilateral occlusion. The results of FEM and BEM analyses are presented mainly in terms of stress distribution on the mandible and on the articular discs. Due to the uncertainty in the determination of the biological parameters, a sensitivity analysis is provided, which demonstrates the impact of the variation of articular disc stiffness and TMJ friction coefficient on the mandible stress peaks and on the occlusal loads (for a given intensity of muscle loads). Moreover a comparison between the effectiveness of the BEM and FEM numerical approaches on this kind of problem is provided.