牙周膜动力分析的几个问题

Dynamic analysis of the periodontal ligament

目的 :分析下颌切牙牙周膜的材料特性和阻尼因素对牙周膜动力分析结果的影响。方法 :通过CT断层扫描得到的图形信息建立人类包括牙齿、牙周膜及牙槽骨的三维有限元模型 ,采用有限元方法分析垂直载荷作用下不同的阻尼时牙周膜的动力响应。结果 :( 1)小变形假设得到的应力与大变形假设相比差别不大 ,两者相差不超过 1.4% ;( 2 )计算得到了阻尼系数 β =0～ 1.2时牙周膜的动力响应 ,一个咀嚼周期结束后牙周膜内侧的残余应力大于外侧 ,唇侧颈缘处最大 ,σr=0 .3 4MPa。结论 :采用小变形假设有助于提高动力分析的效率 ;一个咀嚼周期结束后牙周膜有残余应力存在 。

Objective:To investigate the influences of material properties and damping effect on the dynamic response analysis of human periodontal ligament. Methods: A 3-D finite element model of human teeth and periodontal tissue was built from graphic information obtained by CT scanning. Dynamic analysis was performed to investigate the influence of different damping effects on the stresses of periodontal ligament by the finite element method. Results: (a) No significant difference of stress between small and large deformation assumption was found, the variation was no more than 1.4%.(b) Dynamic response was obtained under β varies from 0 to 1.2. After one mastication period, the residual stress at interior surface was larger than that at exterior surface, with a maximum value of σ r = 0.34 MPa at labial cervical area. Conclusion: Appropriate assumptions on material properties may reduce the cost of analysis. After one mastication period, some levels of residual stresses are in periodontal ligament and influenced by material damp.