不同形状种植体支持单端固定桥的三维有限元分析

Three-dimensional finite element analysis of the cantilever fixed bridge supported by implants with different shapes

背景:种植体的形状影响其生物力学表现,目前对种植支持式单端固定桥的研究多在相同形状种植体进行,对不同形状种植体支持的单端固定桥的比较分析较少。目的:利用三维有限元建模,分析圆柱形、锥形与膨胀式3种种植体支持的单端固定桥在下颌后牙区的生物力学特征。方法:分别建立圆柱形、锥形与膨胀式种植体支持单端固定桥及其支持组织的三维有限元模型,对单端固定桥轴向90°和颊舌向45°分别施加300 N的力,分析皮质骨、松质骨的von Mises应力及种植体-基台复合体的最大位移。结果与结论:①在轴向和颊舌向加载力下,3种模型皮质骨的最大应力峰值远大于松质骨,皮质骨的最大应力峰值均集中于近悬臂种植体远中颈部周围;②膨胀式种植体模型在皮质骨中的最大von Mises应力值最低,在轴向加载力下尤其明显,在松质骨中的von Mises应力值最高;③与轴向加载力比较,颊舌向加载力下3种模型皮质骨、松质骨的von Mises应力峰值及种植体-基台复合体最大位移均增大;在颊舌向加载力下,膨胀式种植体模型的种植体-基台复合体最大位移最小;④结果表明,膨胀式种植体支持的单端固定桥稳定性最好。

BACKGROUND:The shape of the implant exerts an effect on its biomechanics.At present,the research of implant-supported fixed partial denture with cantilever extension mainly focuses on the same shape,and little is reported on the comparison and analysis of implant-supported fixed partial denture with cantilever extension supported by different shape implants.OBJECTIVE:To compare the biomechanical behaviors of cantilever fixed bridges which were supported by three different implants,including cylindrical implant,tapered implant,expandable implant,in the mandibular posterior region with the help of three-dimensional finite element analysis.METHODS:The three-dimensional finite element models of the cantilever fixed bridges which were supported by cylindrical implant,tapered implant and expandable implant and their surrounding tissue in the mandibular posterior region were established were established.The force of300N was applied to the cantilever fixed bridges with axial90°and buccolingual45°to evaluate the maximum von Mises stress(Max EQV stress)of cortical bone and cancellous boneand the maximum displacement in implant-abutment complex.RESULTS AND CONCLUSION:Under axial and buccolingual loads,the Max EQV stress in the cortical bone was higher than that in the cancellous bone.The cantilever fixed bridge which was supported by expandable implant had the lowest Max EQV stress in the cortical bone,especially under axial load,and exhibited the highest Max EQV stress in the cancellous bone.The cantilever fixed bridges supported by three different implants showed an increase in the Max EQV stress of the cortical bone and cancellous bone and the maximum displacement in implant-abutment complex under buccolingual load.The cantilever fixed bridge which was supported by expandable implant had the minimum maximum displacement in the buccolingual direction.To conclude,the cantilever fixed bridge which is supported by expandable implant has best stability.