不同螺距种植体集中载荷的有限元分析

目的:用三维有限元方法分析不同螺距种植体-骨界面应力分布状况,确定利于应力均匀分布的最佳螺纹参数设计.方法:建立包含上部结构的牙种植体、局部下颌骨块三维有限元模型,利用Cosmos/works软件分析在垂直、斜向45° 2 种集中载荷下螺距分别为0.6、 0.8、 1.0 mm的3 种种植体与骨界面的应力分布状况.结果:螺距为0.8 mm种植体周围Von-Mises应力、拉应力、压应力峰值较小,应力分布最均匀;同一螺距种植体斜向载荷下应力显著高于垂直载荷;应力集中主要出现于种植体颈部、皮质骨上缘和种植体末端最下一个螺纹处.结论:螺纹种植体螺距影响骨界面的应力分布和(牙合)力传导,为避免应力集中种植体末端螺纹应进行适当的截齿处理,种植义齿设计和修复时应尽可能减小或避免非轴向力.

Finite element analysis of three kinds of implants with different pitches under concentrated load

Objective; To investigate the stress distribution in implant-bone interface with different pitches by three-dimension finite element analysis method in order to decide the best design of thread parameters for stress distribution. Methods: Built three-dimension finite element models of partial mandible and dental implant with superstructure. The stress distributions in bone and three kinds of implants whose pitches were 0.6, 0.8 and 1.0 mm respectively, under axial and oblique 45 degree to axle concentrated load. Data were analyzed by Cosmos/works software. Results;The maximal Von-Mises stress, tensile stress and compressive stress of implant with 0.8 mm pitch were lower than others, the stress distribution was even. The stresses in the same model under oblique load were much higher than those under axial load. The stress concentrated more on implant neck, upper part of cortical bone and the lowest thread on implant. Conclusion; The pitch of implant has effect on stress distribution in implant-bone interface and the transmission of occlusal force. The lower threads on implant should be cut to avoid the concentration of stress, and the non-axial force should be reduced as possible as we can or avoided when we design and make implant denture.