Numerical simulations of the soft tissues in temporomandibular joint

The influences of different simulations of soft tissues around disk on the movement and stress distribution of the temporomandibular joint(TMJ) were analyzed. A three-dimensional finite element model of the mandible, temporal bone and articular disk was developed according to the CT of a volunteer with asymptomatic joints. The soft tissues around disk were simulated as four types. Contact elements were used to simulate the interaction of the disk with the soft tissues and the articular surfaces. The muscle forces corresponding to centric occlusion were applied to the four models. The results showed that the disks rotated round the condyles in the model with the soft tissues around disk constructed as solid models. Moreover the stresses of the intermediate zones of disk and the anterior regions of condyle and temporal bone were so low. The disks were close to the normal position in the models with the bilaminar zones constructed as solid models, whereas the stress distributions in the TMJs were abnormal. The disks in the model with the attachments of the disks simulated as nonlinear cable elements were in the normal position. Moreover the maximum stress of the disks occurred in the intermediate zones, and the maximum stress of the condyles and temporal bones occurred in the anterior regions. The attachments of disk should be modeled as cable elements, and the interaction of the disk and the articular surfaces should be simulated as contact elements.