Comparative evaluation on three-dimensional finite element models of the temporomandibular joint.

Background: The loads in the temporomandibular joint (TMJ) have been proven to play an important role in its structure and function as well as the etiology and therapy of TMJ disorders. Up to now, finite element (FE) models have been largely used to analyze the stress distributions in TMJs. The disc and the articular surfaces in the TMJs were simulated to be bonded together in many models. In addition, gap elements or contact elements were used to simulate the interaction of the disc and the articular surfaces. However, the comparative evaluation of the three simulations of TMJs has not been studied.

Methods: Three FE models were developed to compare the differences of the simulations on the biomechanics of the TMJs according to the CT images of a volunteer. The interfaces between the discs and the articular cartilages were bonded together and treated as gap elements or contact elements. The muscle forces corresponding to centric occlusion were applied to the three models.

Findings: The stresses in the TMJs were observed to increase in the model with bonded discs and articular cartilages. Gap elements between the discs and the cartilages resulted in the slight magnitude of stresses and the abnormal movement and stress distribution in the TMJs. The condyles and the discs were in the normal position and the stress distributions in the TMJs were similar to the normal biomechanical states when contact elements were simulated between the disc and the cartilages.

Interpretation: The reasonable simulation of the TMJs was to treat the interfaces between the discs and the cartilages as contact elements. The reliable simulation could contribute to the understanding of the stress distributions in TMJs and the basis for the prevention and therapy of the TMJ disorders.