下颌固定义齿基牙齿槽骨降低时不同受载的三维有限元分析

A three-dimensional finite element analysis of the stress distribution in the mandibular FPD produced by forces applied in varying directions and in low periodontal support

目的 研究下颌后牙固定义齿在齿槽骨降低后受载的三维有限元应力分布情况。方法 在建立的下颌固定义齿三维有限元模型的基础上 ,选取桥体、两侧基牙的咬合面施加不同方向的载荷 ,利用MARC有限元分析软件计算并绘制各种载荷下的应力分布图像。结果 固定义齿受垂直载荷时基牙的牙周支持组织的应力分布集中在根尖部位 ,以压应力为主。斜向载荷使基牙支持组织的应力增加且分布不均匀 ,颈部的应力增加较多。齿槽骨的降低使固定义齿基牙支持组织的应力增加 ,但分布规律不变。结论 齿槽骨的降低使固定义齿基牙支持组织的应力增加 ,此类修复体的设计应特别注意基牙牙周组织的健康。

Objective To investigate the stress distribution by changing of the load condition under the forces applied in varying directions and in low periodontal support in the mandibular fixed partial denture(FPD).Methods On the basis of the three-dimensional FE model,we observe the load conditions of the mandibular FPD using the same force in varying directions and in low periodontal support.Stress analysis was executed on a personal computer system with a finite element program MARC.The maximum principal stresses,the minimum principal stress and equivalent Von Mises stress in the abutment roots,pontic,alveolar bone and periodontal support were investigated.Results The compress in the periodontal support and alveolar bone was concentrated in the tip of the abutment roots when FPD was loaded vertically. The direction of the load can influence the stress distribution on the periodontal support interface and the lateral occlusion force was harmful to the abutment and structure of FPD.When the height of periodontal support was reduced the distribution trends of the stresses in the FPD and periodontal support of abutments were similar but the stress was increased than the normal one.Conclusion When the height of periodontal support was reduced,the stress was increased more than the normal one.The health of the periodontal support was very important to the abutment of FPD.