转矩力作用下不同颈部构型对微种植体稳定性的影响

Influence of Neck Design on Mini-implant Primary Stability after Loading with Torque Force

【目的】通过三维有限元方法探讨转矩力作用下新型微种植体不同颈部构型对初期稳定性的影响。【方法】建立新型微种植体及周围骨组织三维有限元模型,加载6 N·mm转矩力。设定微种植体颈部增粗部位的参数变化范围为：高度H0～2.0 mm,直径D 1.3～1.6 mm,和锥度T 0～60°。每次固定两个变量,研究在转矩力作用下另一个变量变化时微种植体的周围皮质骨、松质骨等效应力峰值（Max EQV）及微种植体位移峰值（Max DM）的变化。【结果】随着颈部H的增大,皮质骨Max EQV和微种植体Max DM逐渐减小,但是超过皮质骨厚度后,减小幅度较小;随着D逐渐增大,皮质骨Max EQV和微种植体Max DM逐渐减小;当T为15°时最有利于微种植体的初期稳定性。【结论】转矩力作用下,新型微种植体颈部构型应采用较大直径,高度至少为皮质骨厚度,锥度为适宜角度。

[ Objective ] To investigate the influence of neck design of mini-implant on the primary stability after loading with torque force using three-dimension finite element analysis. [ Methods ] After established new mini-implants and bone block models, a torque force equaling to 6 N·mm was applied on the top of mini-implants. Set the range of the enlarged mini-implant neck parameters value ： height 0 - 2 mm, diameter 1.3 - 1.6 mm and taper 0-60°. Fixed two variables and investigated the action of cortical bone maximum equivalent stress （Max EQV）, cancellous bone maximum equivalent stress （Max EQV）, and maximum displacements （Max DM） of mini-implants as another variable changing under torque force. [ Results ] With the increase of H, Max EQV in cortical bone and Max DM of mini-implant showed a trend of decrease, but the variation amplitude decreased when H exceeds the thickness of cortical bone. There was a decrease in the cortical bone Max EQV and mini-implant Max DM as D increased. In this research range, the stability was good when T equaled to 15°. [Conclusion] The neck of new mini-implant should be designed with large diameter, enough height not less than cortical bone thickness and appropriate taper angle under torque force.