Stress analysis in the mandibular condyle during prolonged clenching: a theoretical approach with the finite element method

Parafunctional habits, such as bruxism and prolonged clenching, have been associated with functional overloading in the temporomandibular joint (TMJ), which may result in internal derangement and osteoarthrosis of the TMJ. In this study, the distributions of stress on the mandibular condylar surface during prolonged clenching were examined with TMJ mathematical models. Finite element models were developed on the basis of magnetic resonance images from two subjects with or without anterior disc displacement of the TMJ. Masticatory muscle forces were used as a loading condition for stress analysis during a 10min clenching. In the asymptomatic model, the stress values in the anterior area (0.100MPa) and lateral area (0.074MPa) were relatively high among the five areas at 10min. In the middle and posterior areas, stress relaxation occurred during the first 2min. In contrast, the stress value in the lateral area was markedly lower (0.020MPa) than in other areas in the symptomatic model at 10min. The largest stress (0.050MPa) was located in the posterior area. All except the anterior area revealed an increase in stress during the first 2min. The present result indicates that the displacement of the disc could affect the stress distribution on the condylar articular surface during prolonged clenching, especially in the posterior area, probably leading to the cartilage breakdown on the condylar articular surface.