数字化可摘局部义齿支架设计优化方法研究

目的 基于数字化可摘局部义齿支架构建三维有限元模型,分析不同建模策略对支架及口腔软硬组织受力的影响,探讨数字化支架优化设计的方法。方法 选择牙列完整、牙周组织健康的成年志愿者1名,在锥形束计算机断层扫描和口外石膏模型扫描的基础上,通过3Shape Dental System软件设计可摘局部义齿支架,利用Mimics、Geomagic Studio和HyperMesh软件对上颌肯氏Ⅱ类牙列缺损模型和可摘局部义齿模型进行三维建模,分别构建简化组和对照组(包含牙齿和牙周膜)三维有限元模型。使用Abaqus/CAE有限元分析软件,分析垂直和斜向45°载荷下两组模型的支架受力情况。结果 简化组模型与对照组模型支架的应力分布规律基本相同,应力值差异无统计学意义。其中垂直载荷下,两组模型均在支架小连接体处出现应力集中,支架远端下沉,最大应力值分别为44.39、51.05 MPa,最大位移值分别为49.05、38.29 μm;斜向载荷时,支架大连接体出现高应力区,Ⅰ杆直角转折处应力集中,最大应力值分别为324.58、303.11 MPa,最大位移值分别为291.86、298.02 μm。结论 采用适当简化模型的方法能够提高建模效率,同时计算结果具有较好的可信度,能够为临床数字化可摘局部义齿支架的优化设计提供参考。

Study on design optimization method of digital removable partial denture framework

Objective To construct a three-dimensional finite element model based on digital removable partial denture framework, to analyze the effects of different modeling strategies on framework and oral soft and hard tissues, and to explore the optimal design method of digital framework. Methods One adult volunteer with complete dentition and healthy periodontal tissues was selected. On the basis of cone beam computed tomography (CBCT)and extraoral plaster model scanning, the removable partial denture was designed by 3Shape Dental System software. The maxillary Kennedy Class Ⅱ dentition defect model and removable partial denture model were established by Mimics, Geomagic Studio and HyperMesh software, and three-dimensional finite element models of the simplified group and control group (including teeth and periodontal ligament)were constructed respectively. The finite element analysis software Abaqus/CAE was used to analyze the force put on two groups of models under vertical and oblique 45° load. Results The stress distribution of framework in the simplified group was basically the same as that in the control group, and there was no significant difference in stress value between two groups. Under the vertical load, stress concentration appeared at the minor connector of the framework in both groups; distal end of the framework sank; the maximum stress was 44.39 MPa and 51.05 MPa, and the maximum displacement was 49.05 μm and 38.29 μm, respectively. Under oblique load, the major connector of the framework had a high stress zone; the stress concentration at the right angle of the Ⅰ bar was concentrated; the maximum stress was 324.58 MPa and 303.11 MPa, and the maximum displacement was 291.86 μm and 298.02 μm, respectively. Conclusion Properly simplified model can improve the modeling efficiency, and calculation results have good credibility, which can provide reference for the optimal design of clinical digital removable partial denture framework.