近远中支托对末端游离缺失修复应力分布的影响

Stress analysis of distal-extension prosthetics with mesial and distal occlusal rest

目的研究下颌末端游离缺失修复中近中与远中支托设计对加载时基牙及支持组织应力分布的影响。方法将初始模型导入HyperMesh 7.0软件建立下颌双侧末端游离缺失模型(765567缺失),模型导入UG5.0软件设计近中支托与远中支托修复方案,导入HyperMesh 7.0软件进行修复方案的有限元网格划分,分别建立近中支托(M模型)与远中(D模型)支托修复有限元模型。分析和比较两种模型在双侧垂直加载时基牙及支持组织最大应力及其分布情况。结果在基牙及其牙周膜,D模型基牙牙冠、牙根及牙周膜的最大应力均显著大于M模型;D模型应力分布主要集中于44牙根,M模型4334牙根应力分布较为均匀。在缺牙区黏膜,M模型最大应力显著大于D模型,两种修复方案模型应力分布分别位于44远中位置和7667位置。两种修复方案模型缺牙区牙槽骨最大应力接近,其中M模型应力分布更广泛。结论采用常规可摘局部义齿修复末端游离缺失时,应优先选择近中支托设计。

Objective To investigate the stress distribution in the abutment and supporting tissues of distal-extension removable partial dentures with mesial and distal occlusal rest under loading. Methods A modular denture model was used to build a model of mandibular dentition defect （765 567 loss） with HyperMesh 7.0 software. Prosthetics with mesial （M model） and distal occlusal rest （D model） were designed with UG 5.0 software,and the finite element models were completed with HyperMesh 7.0 software. The stress distribution was analyzed in the abutment and supporting tissues of distal-extension removable partial dentures with mesial and distal occlusal rest when bilateral vertical forces were applied. Results Compared with M model,D model provided much larger maximum stress in abutments and periodontal membrane. Stress of D model mainly concentrated on roots of 4 4,while that of M model uniformly distributed on roots of 43 34. The maximum stress of M model was significantly larger than that of D model on the mucosa of edentulous region. The maximum stress on alveolar bone of two models＇ edentulous region was equal,while the stress of M model distributed more widely. Conclusion It is prior to select mesial occlusal rest in distal-extension removable partial dentures.