OBJECTIVETo investigate the regulation of stress distribution on TMJ when the location of occlusal load on the mandibular second molar was changed by using the 3-dimensional Finite Element Method (FEM).

METHODSA 3-dimensional FEM TMJ model including left mandibular second molar and mandible was established. In finite element analysis software ANSYS the same boundary constraints were applied to the TMJ FEM model with different load cases. The occlusal loads were applied to simulate ICO load, distal load, and buccal load and the stress values of condyles of the FEM model were calculated.

RESULTSAs the occlusal load was applied to different tooth contact areas with various shapes, the stress distributions of bilateral condyles were found different and asymmetrical. The condyle stress on TMJ FEM model in three loading cases was diverse, not only in stress character but also in stress distribution style. The maximum value of Von Mises in the opposite condyle was 51.513 MPa when ICO load was applied. But when the distal load or the buccal load was applied, the maximum value of Von Mises in the opposite condyle increased to 72.145 MPa or 69.566 Mpa respectively.

CONCLUSIONSThe same level but in different direction of occlusal load that resulted from difference of loading spots by changing the occlusal contact area, would induce different stress features on bilateral condyles.