Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan.
Int J Oral Maxillofac Implants. 2009 Sep-Oct;24(5):877-86.
To investigate the interactions of implant diameter, insertion depth, and loading angle on stress/strain fields in a three-dimensional finite element implant/jawbone system and to determine the influence of the loading angle on stress/strain fields while varying the implant diameter and insertion depth.
Four finite element models were created, which corresponded to two implant diameters and two insertion depths. The jawbone was composed of cortical and cancellous bone and modeled as a linearly elastic medium; the implant had a detailed screw structure and was modeled as an elastic-plastic medium. Static loading was applied to the coronal surface of the implant with a maximum load of 200 N for all the models. Loading directions were varied, with buccolingually applied loading angles ranging from 0 to 85 degrees.
Increases in the angle of force application caused not only increased maximum stress/strain values but worsened stress/strain distribution patterns in the bone and implant. The maximum stress in the bone always occurred at the upper edge of the cortical bone on the lingual side adjacent to the implant. The use of a larger-diameter implant or an increased insertion depth significantly reduced the maximum stress/strain values, improved the stress/strain distribution patterns and, in particular, decreased the stress/strain sensitivity to loading angle.
A narrow-diameter implant, when inserted into jawbone with a shallow insertion depth and loaded with an oblique loading angle, is most unfavorable for stress distribution in both bone and implant. An optimized design of the neck region of an implant, in combination with a carefully controlled implant insertion depth that sets the threads of the implant neck well below the upper edge of the cortical bone, should be especially effective in improving the biomechanical environment for the maintenance of bone in implant/bone systems.
研究种植体直径、植入深度和加载角度对三维有限元种植体/颌骨系统中应力/应变场的相互作用，并确定在改变种植体直径和植入深度的同时，加载角度对应力/应变场的影响。
创建了四个有限元模型，分别对应两种种植体直径和两种植入深度。颌骨由皮质骨和松质骨组成，并被建模为线性弹性介质；种植体具有详细的螺纹结构，并被建模为弹塑性介质。所有模型均在种植体的冠表面施加静态载荷，最大载荷为 200N。加载方向变化，颊舌向加载角度从 0 度到 85 度。
力应用角度的增加不仅导致最大应力/应变值增加，而且还使骨和种植体中的应力/应变分布模式恶化。骨中的最大应力始终发生在种植体相邻舌侧皮质骨的上边缘。使用较大直径的种植体或增加植入深度可显著降低最大应力/应变值，改善应力/应变分布模式，特别是降低对加载角度的应力/应变敏感性。
当窄直径种植体以浅植入深度植入颌骨并加载倾斜加载角度时，对骨和种植体中的应力分布最不利。种植体颈部区域的优化设计，结合精心控制的种植体植入深度，使种植体颈部的螺纹远低于皮质骨的上边缘，对于改善植入物/骨系统中骨的生物力学环境以维持骨特别有效。
