个性化根形种植体的螺纹形态对周围牙槽骨应力分布影响的三维有限元分析

目的 探讨个性化根形种植体的螺纹形态设计对周围牙槽骨应力分布的影响。方法 通过逆向建模技术建立带有矩形、V形、支撑形、反支撑形螺纹和不带螺纹的一段式个性化根形牙种植体的三维有限元模型,分别加载与种植体长轴呈45°角及0°角的100 N的力,导入Ansys 16软件计算不同螺纹个性化根形种植体周围骨组织von Mises应力分布的情况。结果 倾斜45°角加载时,皮质骨内应力主要集中于种植体颈部周缘及螺纹顶端,松质骨内应力主要分布于种植体唇侧颈部、螺纹顶端和植体根尖部。垂直(0°角)加载时,皮质骨内应力主要集中于种植体颈部处,松质骨内应力主要分布于根尖部以及唇侧根下部。加载时,螺纹组相对无螺纹组应力分布更加均匀,各螺纹组间无明显差别。松质骨内各螺纹植体应力主要集中在螺纹顶端处,根尖处的应力集中较少。与矩形螺纹相比,V形、支撑形和反支撑形种植体在松质骨内的应力分布更为均匀。结论 螺纹设计可以优化个性化根形种植体周围皮质骨和松质骨内的应力分布,减小皮质骨内的应力集中,V形、支撑形、反支撑形相比矩形螺纹设计,应力分布更加均匀。

Influence of thread shapes of custom-made root-analogue implants on stress distribution of peri-implant bone: A three-dimensional finite element analysis

Objective: To explore the effects from the thread shapes of custom-made root-analogue implant (RAI) on distributions of von Mises stress around the peri-implant bone.Methods: Five one-stage RAI three-dimensional finite element (FE) models with different thread shapes (V-shaped design, square design, buttress design, reverse buttress design and none thread design) and congruent bone were created through reverse engineering technology. The data of the five models were imported into the FE analysis software to calculate. A force of 100 N was applied parallelly and of 45° to the implant axis respectively. Analysis was performed to evaluate the von Mises stress distributions at the peri-implant regions with the help of the Ansys 16 software.Results: The von Mises stresses distributed mostly at the implant cervical regions and the tip ends of the threads on the cortical bone under oblique loading, while on the cancellous bone, the stresses concentrated mostly on the implant lateral cervical regions, the tip ends of the threads and the apical regions. When under vertical loading, the von Mises stresses distributed mostly at the implant cervical regions on the cortical bone while at the tip ends of the threads and the lateral apical regions on the cancellous bone. The von Mises stresses were better distributed on the thread groups under both kinds of loadings compared with no thread design. But there was no obvious difference among the different thread groups. The concentrations of the von Mises stresses on the cancellous bone in the thread groups were mostly at the tip ends of the threads while less in the apical area. The von Mises stresses were better distributed on the cancellous bone on the other three thread designs than on square design.Conclusion: Thread designs are advocated for the reason that adding thread designs to the RAI standard design will have a positive effect on stress distributions at the peri-implant regions and it will reduce the concentrations of von Mises stresses on the cortical bone. From the standpoint of the stress distribution, V-shaped design, buttress design and reverse buttress design are more suitable for RAI than square design. There is no difference of the distributions of the von Mises stresses in the RAI between different thread designs.