Contribution of finete element modeling to assessment of TMJ loading patterns.

Simulations were performed with a dynamic biochemical model of the human masticatory system that included the deformable cartilaginous structures of the temporomandibular joints as finite element models. This model predicted jaw movements as a result of force patterns of the masticatory muscles. Tension, compression and shear stresses as well as the pressure distribution were predicted during jaw open-close movements. It was found that the articular disc is able to reduce load concentrations between the articular eminence and mandibular condyle at the cost of relatively large shear stresses. Separately, predicted changes in pressure distribution inside the disc gave rise to the idea that its interstitial fluid could be subject to a continuous mixing flow pattern

Biomechanical analysis of the influence of friction in jaw joint disorders

Objective Increased friction due to impaired lubrication in the jaw joint has been considered as one of the possible causes for internal joint disorders. A very common internal disorder in the jaw joint is an anteriorly dislocated articular disc. This is generally considered to contribute to the onset of arthritic injuries. Increase of friction as caused by impairment of lubrication is suspected to be a possible cause for such a disorder. Method The influence of friction was addressed by analysis of its effects on tensions and deformations of the cartilaginous structures in the jaw joint using computational biomechanical analysis. Jaw open-close movements were simulated while in one or two compartments of the right joint friction was applied in the articular contact. The left joint was treated as the healthy control. Results The simulations predicted that friction primarily causes increased shear stress in the articular cartilage layers, but hardly in the articular disc. Conclusions This suggests that impaired lubrication may facilitate deterioration of the cartilage-subchondral bone unit of the articular surfaces. The results further suggest that increased friction is not a plausible cause for turning a normally functioning articular disc into an anteriorly dislocated one