数值分析力矩比对尖牙平移移动的影响

目的通过有限元方法分析不同大小力矩比(M/F)和力对尖牙位移、牙周膜应力的影响。方法根据临床CT图像构建三维下颌模型,应用只有矫治力和有不同M/F矫治力系统对尖牙进行平移移动的模拟计算。分析在每一种情况下尖牙的位移平移情况,并推导出最优的能实现尖牙平移的矫治力系统。结果在所有计算中牙周膜应力均随力增大而增大。牙周膜应力则先随M/F增加而减小,达到一定值M/F=10.1 mm后(最优M/F)随M/F增加而增大。尖牙的初始位移都是倾斜移动,当采用精确的最优M/F时,尖牙的初始位移最接近平移移动。结论尖牙移动需要适合的力值,防止牙根吸收,然而平移移动需要有最佳的M/F,且是必须在生理适合力范围内的M/F。了解力和力矩对牙齿平移的影响有助于施加更加合理的矫治力系和设计更加合理的正畸器械装置。

Effects of Moment-to-Force Ratio on Canine Translation by Numerical Analysis

Objective To study the influence of different moment-to-force ratios (M/F) and forces on canine displacement and periodontal ligament (PDL) stress. Methods A three-dimensional (3D) mandibular model was established based on CT images. The orthodontic force systems without a moment and with various M/F were applied to the canine for numerical calculation of its translation. An optimum force system to realize canine translation was validated by analyzing translation displacement of the canine in each case. Results The PDL stress increased with an increase in force magnitude in all cases. The PDL stress first decreased with an increase in the M/F before the M/F reached the optimum value (M/F=10.1 mm), and then increased with an increase in the M/F. The initial displacement of the canine was inclined movement, which was most close to translation when the precise optimum M/F was applied. Conclusions The canine movement requires an appropriate force to prevent root absorption, whereas the translation movement requires an optimal M/F value which is within the physiological range. Understanding the influence of force and moment on tooth translation can help to apply more reasonable orthodontic force system and design more reasonable orthodontic device.