下颌第一恒磨牙三维有限元模型的建立及应力分析

目的建立更合理的下颌第一恒磨牙三维有限元模型并研究其内应力分布。方法运用MSC．NASTRAN软件建屯含有牙釉质、牙本质、髓腔、牙周膜和牙槽骨的下颌第一恒磨牙三维有限元模型并分析不同受力状态下牙齿硬组织的应力分布。结果在5种载荷下牙釉质的最大vonMises应力和最大压应力均比牙本质的大，而最大拉应力则小于牙本质。垂直载荷和颊．舌斜向载荷时，牙釉质和牙本质内的应力最小，而舌-颊斜向载荷下应力最大。牙颈部、根分歧和近中舌根管壁根尖部是主要的应力集中区。结论牙齿硬组织内应力集中区及应力值的变化与牙齿接受咬合力的方向密切相关。

Establishment of the three-dimensional finite element model of the first permanent mandibular molar and its stress analysis

Objective To establish more rational three dimensional finite element model (FEM) of the first permanent mandibular molar and to study the internal stress distribution. Methods The FEM was applied to analyze the stress distribution of the first permanent mandibular molar under various loading conditions. Results Under all five loading conditions, the maximum von-Mises stress and compressive stress in enamel were larger than that in dentin, and the tensile stress in enamel was smaller than that in dentin. When vertical force and buccal-lingual oblique force were loaded, the stresses in the enamel and dentin were minimum; when lingual-buccal oblique force was loaded, the stresses were maximum; the stresses were mainly distributed at cervical region, furcation and apical area of the mesial-lingual root canal wall. Conclusions The stress value changes and stress distribution in the enamel and dentin were closely related with the direction of the occlusion force.