不同高度牙周支持组织的下颌前磨牙三维有限元应力分析

目的：观察不同牙周支持高度的牙齿受力时，牙体内部尤其是牙根的受力的状况。方法：以电子计算机技术建立了包括牙齿、牙周膜、硬骨板、松质骨和皮质骨的下颌前磨牙三维有限元模型。分别删去2层、4层、6层牙周支持组织(分别占牙周支持高度的20%、40%、60％．)产生代表4种不同牙周支持高度的三维有限元模型。分别计算出不同同载荷下不同牙槽骨高度下牙体组织的最大拉应力、最大压应力和Von Mises应力。结果：随着牙槽骨的降低，牙体组织内的最大等效应力和最大压应力都逐渐增大，最大拉应力变化不明显。最大应力部位由牙颌部逐渐移至牙根中部。结论：健康的下颌前磨牙较牙槽骨有吸收的下颌前磨牙更易患楔状缺损。而牙槽骨吸收的下颌前磨牙较止常下颌前磨牙易根折。

Three-dimensional finite element analysis the stress of the normal mandibular premolar under various degree of periodontal support

Objective: To determine the locations of stress concentrations within a mandibular premolar under various degree of periodontal support. Methods: The three-dimensional finite element model, consisting of tooth, periodontal ligament, alveolar bone, was developed. Four levels of periodontal support reduction (0%, 20%, 40%, 60%) were simulated by varying the socket depth. To calculate the maximum priciple stress,the minimum priciple stress and the Von Mises stress of the tooth under various loadings respectively. Results: The stresses are increased and the location of the stress concentration shifted apically as periodontal support diminished. Periodontal support reduction shifted the location of highest stress away from the cervical region to the root. Conclusion: Non-carious cervical lesion is less likely to occur on periodontal support diminished teeth compared to stable teeth, but the vertical root fracture is more.