牵引力大小对关闭间隙时滑动阻力影响的三维非线性有限元研究

Comparision of the friction resistance in sliding mechanics at different forces level for space closing --a nonlinear finite element study

目的探讨滑动法关闭间隙时牵引力大小对弓丝滑动的影响。方法在全牙列及其牙周组织、弓丝、矫治器的三维有限元模型上，用非线性方法计算不同大小牵引力作用下沿0．048cm×0．064cm（0．019英寸×0．025英寸）不锈钢弓丝滑动时，弓丝与托槽的接触点数目、接触力大小等影响滑动摩擦力大小的因素。结果牵引力小于或大于150g时，后牙接触点多、接触正压力大，滑动阻力较大，使滑动受限；150g牵引力时，整段弓丝特别是后段弓丝与托槽接触点均匀，后段弓丝接触正压力最小，滑动阻力最小。结论使用0．048cm×0．064cm（0．019英寸×0．025英寸）不锈钢弓丝滑动关闭间隙时，过小、过大的牵引力均不利于弓丝的滑动，150g力时滑动阻力最小，有利于弓丝的滑动。

Objective To study effects of retracting force on the friction resistance during space closing. Method A Three-dimensional Finite Element Model, composed of upper dentition（P1 extracted） with. 022＂ straight wire brackets and 0. 019＂× 0. 025＂ss arch wire, as well as periodontal tissues was set up. Each of 50, 100, 150, 200, 300g retracting force was applied to close the space. The contact points, contact forces between wire and slots were analyzed with nonlinear method. Results When the retracting force less than or more than 150g, the contact points are more and the contact forces are larger on the arch wire at the posterior teeth, implying the resistance to sliding is comparatively larger. With 150g retracting force, the contact points and contact forces on the posterior arch wire are the least and smallest, friction resistance was the least. Conclusion 150 g retracting force is the best force for space closing on 0. 019＂× 0. 025＂ss wire with sliding mechanics. With the force more or less than 150g, the friction resistance will be higher.