Senior Lecturer, Army Medical College/Armed Forces Institute of Dentistry, National University of Medical Sciences (NUMS), Islamabad, Pakistan.
Assistant Professor, Supervisor, Department of Prosthodontics, Army Medical College/Armed Forces Institute of Dentistry, National University of Medical Sciences (NUMS), Islamabad, Pakistan.
J Prosthet Dent. 2019 Jun;121(6):935-940. doi: 10.1016/j.prosdent.2018.08.011. Epub 2019 Jan 31.
A consensus regarding the effects of platform switching on peri-implant marginal bone levels is lacking. Finite element studies have reported contradictory results.
The purpose of this finite element analysis study was to evaluate stress distribution in platform-switched (PS) and platform-matched (PM) implants and their surrounding bone.
An implant (4.5×11 mm) was modeled and screwed into a human mandibular bone block using a computer-aided design (CAD) software program. Two separate models were generated: (1) PM, 4.5-mm implant with 4.5-mm-wide abutment and (2) PS, 4.5-mm implant with 3.5-mm-wide abutment. Implant components were modeled with linear isotropic properties and bones with anisotropic properties. Vertical (200 to 800 N) and oblique (50 to 150 N) forces were applied to each model to simulate occlusal loads. Linear elastic analysis was performed using ANSYS Workbench 16. von Mises equivalent stresses in the implant assemblies and peri-implant bone were calculated and compared with independent samples t test (α=.05).
von Mises equivalent stress values under simulated axial and nonaxial occlusal loads were lower for PM than for PS implant assemblies. However, the differences were not statistically significant. Stress within the peri-implant bone was significantly higher for the PM group than for the PS group (P<.001).
Platform switching decreased stress within peri-implant bone and may help limit marginal bone resorption.
关于平台转换对种植体边缘骨水平的影响，尚未达成共识。有限元研究报告的结果相互矛盾。
本有限元分析研究的目的是评估平台转换（PS）和平台匹配（PM）种植体及其周围骨的应力分布。
使用计算机辅助设计（CAD）软件程序，对植入物（4.5×11mm）进行建模并拧入下颌骨骨块。生成了两个单独的模型：（1）PM，具有 4.5mm 宽基台的 4.5mm 种植体，和（2）PS，具有 3.5mm 宽基台的 4.5mm 种植体。采用各向同性线性特性对植入物组件进行建模，采用各向异性特性对骨骼进行建模。对每个模型施加垂直（200 至 800N）和倾斜（50 至 150N）力，以模拟咬合负荷。使用 ANSYS Workbench 16 进行线性弹性分析。计算了种植体组件和种植体周围骨中的 von Mises 等效应力，并通过独立样本 t 检验（α=.05）进行比较。
在模拟轴向和非轴向咬合负荷下，PM 种植体组件的 von Mises 等效应力值低于 PS 种植体组件，但差异无统计学意义。PM 组的种植体周围骨内的应力明显高于 PS 组（P<.001）。
平台转换降低了种植体周围骨内的应力，可能有助于限制边缘骨吸收。
