Herbst矫治器在不同重建时对髁突软骨rn表面应力分布的影响

摘要

Objective:The distribution of stress on the surface of condylar cartilage was investigated. Methods: Three-dimensional model of the 'Temporomandibular joint mandible Herbst appliance system' was set up by SUPER SAP software (version 9.3). On this model, various bite reconstruction was simulated according to specified advanced displacement and vertical bite opening. The distribution of maximum and minimum principal stress on the surface of condylar cartilage were computerized and analyzed.Results: When Herbst appliance drove the mandible forward, the anterior condyle surface was compressed while the posterior surface was drawn. The trend of stress on the same point on the condyle surface was consistent in various reconstruction conditions, but the trend of stress on various point were different in same reconstruction conditions. Conclusion: All five groups of bite reconstruction (3～7mm advancement, 4～2mm vertical bite opening of the mandible) designed by this study can be selected in clinic according to the patient's capability of adaptation, the extent of malocclusion and the potential and direction of growth.%目的:从生物力学角度研究Herbst矫治器在不同的重建状态下前导下颌，对髁突软骨表面应力分布的影响,为临床应用提供理论依据。方法:采用三维有限元方法，在已建立的颞下颌关节—下颌骨—Herbst矫治器系统的三维正交各向同性有限元模型上，根据临床和相关文献设计重建的类型，在髁突的矢状向及冠状向上分别选取相应节点，计算相应的最大主应力与最小主应力值。结果:不同重建时，髁突软骨表面同一部位的应力值相差不大，在相同重建时，髁突软骨表面不同部位的应力值相差较大。在每一种重建组合中，矢状向髁突软骨后方有较大范围的张应力区，而髁突前斜面有较大范围的压应力区。冠状向髁突软骨表面的内、外侧斜面都主要为压应力区。结论:本文设计的5组重建类型（下颌水平前伸3～7mm，垂直打开4～2mm）在髁突表面的应力分布相差不大，均在生理承受范围内。