Analysis of the distribution of stress and deformation in single implant-supported prosthetic units in implants of different diameters

Abstract Introduction When stress and strain levels in the bone-implant system exceed It's capacity, a mechanical fatigue occurs, resulting in collapse and loss of osseointegration. Objective Analyze biomechanical behavior in single implant-supported prosthesis with implants of different diameters in the posterior mandible. Material and method Three different finite element models of Cone-Morse implants with the same height were created, varying the diameter (3.3 mm, 4.1 mm and 4.8 mm). The mandibular first molar area was the location of the implant, with It´s component and overlying prosthetic crown. The jawbone was composed of cortical and cancellous bone. Refined mesh of 0.5 mm was created in the critical interfaces to be analyzed. The loading of the models was performed at the point of occlusal contact with an occlusal load of 400 N. Result Maximum stress and strain occurred in the cervical regions of the implants in all groups, either in the implants or in components as well as in the analysis of cortical bone. The greater the diameter, the lower the stress and strain found in the implant. The 3.3 mm group had the highest strain in peri-implant cortical bone, and the 4.1 mm group had the smallest deformation, significantly lower than in the 4.8 mm group. Conclusion Although the biggest implant diameter (4.8 mm) appears to have lower values of stress and strain, the group of intermediate implant diameter (4.1 mm) showed less deformation rate in the cortical peri-implant bone. Therefore it is concluded that the 4.1 mm implant platform presented a more biomechanically effective peri-implant bone maintenance.

【摘要】当骨-种植体系统的应力与应变水平超出其承载极限时，会发生机械疲劳，进而导致结构塌陷及骨整合（osseointegration）丧失。
研究目的：分析下颌后牙区不同直径种植体支持的单颗种植修复体的生物力学行为。
材料与方法：构建3种高度一致、直径分别为3.3 mm、4.1 mm及4.8 mm的锥Morse种植体（Cone-Morse implants）有限元模型（finite element models）。种植体植入下颌第一磨牙区域，配套相应种植组件及上部修复牙冠；颌骨由皮质骨（cortical bone）与松质骨（cancellous bone）构成，在待分析的关键界面处设置尺寸为0.5 mm的精细化网格。模型加载采用咬合接触点位加载方式，施加的咬合载荷（occlusal load）为400 N。
结果：所有实验组的最大应力与应变均出现在种植体的颈部区域，针对种植体自身、其配套组件以及皮质骨的分析均得到一致结论。种植体直径越大，其自身所承受的应力与应变水平越低。其中，3.3 mm直径组的种植体周围皮质骨应变最高；4.1 mm直径组的变形量最小，且显著低于4.8 mm直径组。
结论：尽管直径最大的4.8 mm种植体的应力与应变数值更低，但中等直径（4.1 mm）的种植体在种植体周围皮质骨的变形率更低。因此可得出结论：4.1 mm直径的种植体平台可实现更具生物力学有效性的种植体周围骨组织维持。