动静态下仿生型钛种植体界面应力与疲劳行为的有限元分析

目的：研究静态与动态加载下仿生型种植体骨界面应力分布状况和疲劳行为，为研发能有效地转移应力至周围骨组织的新型种植体提供理论依据。方法：采用CAD（Pro/E Widefire 2.0）软件建立颌骨和钛种植体的三维有限元模型，设置全致密型（1号）和仿生型（2号）两种结构钛种植体，采用Ansys Workbench 10.0软件分析静态与动态加载下种植体骨界面应力分布状况，并对2号种植体进行疲劳行为分析。结果：在相同载荷下，1号和2号种植体在皮质骨区均为高应力区，2号种植体界面最大应力值、高应力区域面积、根端区最大应力值均低于1号种植体，从上至下种植体骨界面应力呈均匀递减趋势。动态加载的界面应力比静态的界面应力高17.15%。两种加载方式下，两种种植体在皮质骨区界面最大应力值无差别；在松质骨区， 1号的界面最大应力值比2号高75.97%；在根端区，1号的界面最大应力值比2号高22.46%，种植体界面最大应力远小于纯钛的屈服强度。2号种植体颈部皮质骨边缘的最大应力值比1号高7.85%，皮质骨边缘的最大应力值未达到皮质骨的屈服强度。预载50~300 N动态载荷，致密芯的安全系数均在10以上，随载荷加大，多孔层的界面应力呈线性增加，动态加载轴向300 N 和颊舌向45°25 N时，多孔层界面最大应力为11.38 MPa。结论：仿生型种植体有利于松质骨区及根端区界面应力转移到周围骨组织，其几何结构设计能耐受正常咀嚼的疲劳载荷，是安全的设计。

Finite element analysis for interfacial stress and fatigue behaviors of biomimetic titanium implant under static and dynamic loading conditions

Objective To investigate the stress distributions on implant-bone interface and fatigue behaviors of biomimetic titanium implant under static and dynamic loading conditions to provide theoretical basis for a new implant which may effectively transfer the stress to surrounding bones. Methods A 3-D finite element model of a posterior mandible segment with an implant bone was constructed by a CAD (Pro/E Widefire 2.0) software. Two different implant models (a dense implant No.1 and a biomimetic implant No.2) were designed. The stress distributions on bone-implant interface under dynamic and static loading conditions were analyzed by Ansys Workbench 10.0 software, as well as the fatigue beha-vior of the biomimetic implant. Results The cervical cortical bones in the 2 implants were all high stress region under the same loading condition. The maximum von Mises stress on the interface and high-stress region in the cancellous bone region, and the maximum stress in the root region of the biomimetic implant were lower than those of the dense implant. The stress on the implant-bone interface decreased from the top to the bottom. The stress in the cervical cortical bone under the dynamic loading was 17.15% higher than that of the static loading. There was no significant difference in maximum stress at the cortical bone region between the dynamic and static loading conditions. The maximum stress of the dense implant in the cancellous bone region was 75.97% higher and that in the root region was 22.46% higher than that of the biomimetic implant. The maximum stress on the implant-bone interface was far less than the yield strength of pure titanium. The stress distribution in the cortical region of the biomimetic implant was 7.85% higher than that of the dense implant, and the maximum stress in the cortical bone was smaller than the yield stress of cortical bone. Within the dynamic loading of 50-300 N, the safety coefficient was all higher than 10, and with the increase of loading pressure, interface stress in the cancellous region increased linearly. Under the loading of 300 N in the axial and 25 N in the lingual 45°, the maximum stress was 11.38 MPa. Conclusion Biomimetic style implant can effectively transfer the implant-bone interface stress to surrounding bones in the cancellous bone and root region, and the structure with the improved design is safe under normal loading pressure.