种植体结构改变对种植体-骨界面皮质骨区应力影响的三维有限元分析

Effect of implant structural changes on the cortical bone stress distribution and peak of the implant-bone interface: a three-dimensional finite element analysis

背景:种植体-骨界面的生物力学效应是骨吸收重要的影响因素之一。模仿天然牙周膜的新结构种植体或可改善其界面应力的分布情况。目的:探讨不同的咬合负载条件下,改变传统种植体内部结构对种植体-骨界面皮质骨区应力分布、峰值的影响,为新结构种植体的优化设计及临床应用提供理论依据。方法:用Pro/ENGINEER软件建立新结构的种植体(模型A)与无螺纹的传统柱状种植体(模型B)的数字模型,采用Ansys软件分析在相同骨质及相同受力环境下种植体-骨界面皮质骨区应力峰值、应力带分布的变化规律。结果与结论:垂直加载时,模型A在不同受力大小时应力峰值均较模型B降低17.54%;45°加载时,模型A应力峰值较模型B降低(2.59%),模型B的高应力区向颊侧集中趋势明显。咀嚼模拟加载时,模型A的应力峰值均较模型B低,其差值在施力方向与种植体轴向夹角(β)等于12°时最大(0.353 2 MPa),在β>12°后逐渐减小;并且模型A在促进骨组织生长最适应力峰值、维持骨组织健康应力峰值两个量化指标中,均比模型B适用角度范围大(A:0°-28°,0°-58°;B:0°-24°,0°-56°)。提示优化设计种植体结构的改变可改善种植体-骨界面皮质骨区的应力分布,降低应力峰值,可在更大范围内降低骨皮质吸收的风险。

BACKGROUND：The biomechanical effect of the implant-bone interface is one of the most important factors for bone resorption. The new structure of the periodontal-ligament-like implants may improve the distribution of the interfacial stress. OBJECTIVE：To discuss the effect of the internal structure changes of traditional implants on the cortical bone stress distribution and peak at the implant-bone interface under different occlusal load conditions, so as to provide a theoretical basis for the optimization design and clinical application of new structure implants. METHODS：Two kinds of digital models, new structure implant （model A） and non-threaded cylindrical implant （model B）, were established by Pro/ENGINEER software. Variations of the stress peak and stress distribution of implant-bone interface cortical bone area under the same bone and force environment were analyzed using Ansys software. RESULTS AND CONCLUSION： Under a vertical loading, the stress peak under different forces was reduced by 17.54% in model A compared with model B; under a 45° loading, the stress peak of model A was reduced by 2.59% compared with model B, and it showed an evident tendency of high stress area focusing to the buccal side of model B. Under the chew-simulation loading, the stress peak of model A was lower than that of model B. The biggest difference （0.353 2 MPa） appeared atβ=12°（β is the angle of force direction and the implant axis）, and it gradualy reduced atβ 〉 12°. At the same time, model A had a wider range of application degree compared with＆nbsp;model B in two quantitative indicators, including optimal peak stress of promoting bone tissue growth and stress peak of maintaining healthy bone tissue. These results suggest that the optimized structure of implants contributes to improve the cortical bone stress distribution at the implant-bone interface, decrease the peak stress, and reduce the risk of cortical bone absorption in a wider range.