种植体直径和长度在Ⅲ类骨质中的优化选择

目的应用Ansys DesignXplorer模块，分析圆柱形种植体直径和长度同时连续变化时对Ⅲ类骨质的颌骨应力的影响，为临床选择和设计种植体提供理论依据。方法建立包含圆柱状种植体的下颌骨Ⅲ类骨质的骨块三维有限元模型，设定种植体直径变化范围为3．0～5．0mm，种植体长度变化范围为6．0～16．0mm，观察直径和长度变化对颌骨Von Mises应力峰值的影响。同时进行颌骨Von Mises应力峰值对变量的敏感度分析。结果随着直径和长度的增加，垂直向加载时，皮、松质骨的EQV应力峰值分别降低了65．3％和76．8％；颊舌向加载时，皮、松质骨的VonMises应力峰值分别降低了76．1％和78．0％；当直径大于3．95mm，同时长度大于10．5mm时，应力峰值响应曲线的切斜率位于-1和0之间；在垂直向加载和颊舌向加载时，长度和直径分别对皮质骨EQV应力峰值的影响更明显。结论种植体直径增加更有利于改善颌骨颊舌向加载下的应力分布，种植体长度的增加更有利于改善颌骨垂直加载下的应力分布。从生物力学角度而言，对于m类骨质在临床上选择种植体时，种植体的直径应不小于3．95mm。种植体的长度应不小于10．5mm。

Optimum selection of diameter and length of cylinder implant in type Ⅲ jaw bone

Objective To investigate the effects of changes of diameter and length of screwed implant on jaw stress in the region of type Ⅲ bone. Methods Three-dimensional finite element model of type m bone fabricated with screwed implant was established. The range of implant diameter was set from 3.0 mm to 5.0 mm, and that of length from 6.0 mm to 16. 0mm The forces of 200N and 100N were applied along the axis of implant and bucealingual direction respectively. The maximum equivalent stresses in jaw bone were evaluated, and the sensitivities of stresses to the variables were also examined. Results The maximum Von Mises stresses in cortical and eaneenous bones decreased by 65.3% and 76. 8% respectively with diameter and length increasing under the axial load, and by 76. 1% and 78.0% respectively under bueealingual load. When diameter exceeded 3.95mm and length exceeded 10. 5 mm, the tangent slope rate of the maximum Von Mises stress response curves ranged from -1 to 0. The variation of the maximum Von Mises stresses in cortical bone was more sensitive to length and diameter under axial and bueeolingual load respectively. Condusion The stress of jaw bone was affected more by diameter of implant than by implant length. Diameter exceeding 3.95 mm and length exceeding 10. 5 mm were optimal selection for a screwed implant in the type Ⅲ bone.