牙齿磨耗后颞下颌关节应力分布的三维有限元研究

目的：计算机模拟牙齿不同程度磨耗、颌垂直距离减小时，三维有限元分析颞下颌关节内的应力分布变化。方法：应用以往研究所建正常颞下颌关节三维有限元模型，分别将下牙列分层删除从上至下1／3、1／2及全部的单元，并改变咀嚼肌加力方向。应用ANSYS6．1分析颞下颌关节内的应力变化。结果：随着磨耗程度的加重，髁状突表面的应力增加较多。关节盘等效应力增加的速度较髁状突、关节窝要大；关节盘的后带后缘，还有关节盘中带、后带的中间、外侧区有应力集中表现；磨耗越重，变形越大，关节盘越薄。颞骨关节窝不但应力值增加，最大应力的位置也由关节结节后斜面向顶部移动。结论：牙齿磨耗可造成颞下颌关节应力的明显增加及特定的应力集中区。

A study on the stress distribution in the temporomandibular joint affected by tooth wear with three-dimensional finite element method

Objective: To analyze the changes of the stress in the TMJ affected by different degrees of tooth wear onthe model, which was simulated by the computer. Methods: In order to simulate different levels of tooth wear, the lowerteeth elements of our 3D FEM were deleted 1/3, 1/2 and all from the top down apllying ANSYS6.1 program. By thedirectional changes of the masticatory muscles were made for modifying the decrease of the OVD. Solving was done byANSYS6.1. The stress distribution and deformation in the TMJ were analysed through the Post-prosessing of ANSYS6.1programm. Results: The stresses on the surface of the condyle increased obviously as the tooth wear aggravated. Theincrease rate of the Von Mises stress in the articular disc was higher than that in the condyle and the glenoid fossa. Stressfocused on the lateral of the edge of posterior band, which was the junction of the bilaminar region and the posterior bandof the disc, the middle and lateral of intermediate zone and posterior band of the disc. The more severe the teeth wear, themore obviuse deformation the disc became . The stresses in the glenoid fossa increased with the deterioration of toothwear, while the location of the biggest stress is shifting from posterior inclined plane of the articular eminence to roof ofthe glenoid fossa. Conclusions: Tooth wear results in obvious increament of the stress in the TMJ. The stresses concentrationare in some special area.