Influences of occlusal and skeletal discrepancies on biomechanical environment in the TMJ during maximum clenching: an analytic approach with the finite element method.

The purpose of this study was to investigate the influences of occlusal and skeletal discrepancies on temporomandibular joint (TMJ) stresses during maximum clenching. A three-dimensional (3-D) finite element model of the mandible including the TMJ was developed as a standard model. Furthermore, nine modified models were established; one dentoalveolar open bite model and eight skeletal open bite models with varying gonial angles or mandibular plane angles (FMAs). For the dentoalveolar open bite model, the TMJ stresses were larger than those for the standard model, although the distribution pattern was not essentially varied. In the skeletal open bite model with greater gonial angle or FMA, the TMJ stresses were significantly larger than those in the dentoalveolar open bite model. In conclusion, the TMJ stress was affected by occlusal and/or skeletal discrepancies, if coexisted in particular, indicating the association with degenerative changes of the TMJ components.