种植体直径和长度在Ⅰ类骨质中的优化选择

Optimal Selection of Cylinder Implant Diameter and Length in Type Ⅰ Jaw Bone

目的：应用Ansys Design Xplorer模块，研究圆柱形种植体直径和长度同时连续变化对Ⅰ类骨质的颌骨应力影响，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Ⅰ类骨质骨块的三维有限元模型，设定种植体直径（D）变化范围为3．0—5．0mm，种植体长度（L）变化范围为6．0—16．0mm，观察D和L变化对颌骨Von Mises应力峰值的影响。同时进行颌骨VonMises应力峰值对变量的敏感度分析。结果：随着D和L的增加，垂直向加载时，皮、松质骨的EQV应力峰值分别降低了54．5％和70．2％，颊舌向加载时，皮、松质骨的EQV应力峰值分别降低了73．5％和75，1％；当D大于3，8mm同时L大于9．0mm时，应力峰值的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，变量D比L更易影响皮质骨的EQV应力峰值。结论：种植体的直径比长度更易影响皮质骨的应力大小。从生物力学角度而言，对于Ⅰ类骨质，在临床上选择种植体时，种植体的直径应不小于3．8mm，种植体的长度应不小于9．0mm。

Objective： To evaluate continuous and simultaneous variations of screwed implant diameter and length in the region of type Ⅰ bone. Methods： We created the mandible segment finite element model of type Ⅰ bone with screwed implant. The range of implant diameter （D） was set from 3.0mm to 5.0mm, and that of implant length （L） from 6.0mm to 16. 0mm. Forces of 200N and 100N were applied along axis of implant （AX） and buccolingual direction （BL）, respectively. The maximum equivalent stresses in jaw bone were evaluated, and the sensitivities of stresses to the variables were also evaluated. Results： Under axial load, the maximum Von Mises stresses in cortical and cancellous bones decreased by 54. 5% and 70.2% respectively with increasing D and L. And under buccolingual load, those decreased 73.5% and 75.1% respectively. When D exceeded 3.8mm and L exceeded 9.0mm, 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 D than to L. Conclusion： Buccolingual force is apt to be influenced by the implant parameters. Implant diameter affects the stress of cortical bone more than length does. Implant diameter exceeds 3.8mm and implant length exceeds 9. 0mm are optimal selection for a screwed implant in the type I bone by biomechanical consideration.