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目的评估弓丝变形历史对弓丝产生的正畸力的影响。方法建立未变形状态的弓丝和托槽的有限元模型,根据激光扫描牙齿石膏模型获得托槽的临床位置;使用热-机械记忆合金模型,通过有限元方法按照两种不同的路径将弓丝和托槽移动到临床位置,对两种路径获得的正畸力进行比较,并分析产生这种差异的原因。结果两种不同加载路径获得NiTi合金弓丝产生的正畸力的相对差值范围在0.3～8.0,存在明显的差别;先过加载后反向卸载到研究状态会减少变形路径对正畸力的影响,但弓丝上不同部位减少程度差别加大,部分数据误差增大。结论镍钛合金弓丝产生的正畸力与弓丝变形历史有着直接的关系,正畸力的求取需要追踪记忆合金弓丝的变形历史。
Objective To evaluate the effect of arch deformation history on the orthodontic force of arch wire. Methods The finite element model of archwire and bracket in undeformed state was established. The position of brackets was obtained according to laser gypsum model. Using the model of thermo-mechanical memory alloy, two different paths of archwire And brackets to move to a clinical position, comparing the orthodontic forces obtained with the two pathways and analyzing the causes of this discrepancy. Results The relative difference of the orthodontic force of the NiTi alloy arch wire obtained by two different loading paths ranged from 0.3 to 8.0. There was a significant difference between the two methods. The reverse unloading to the research state after the overloading reduced the effect of deformation path on the orthodontic force However, the difference between the reduction of different parts of the arch wire increased with the increase of some data errors. Conclusion The orthodontic force produced by nickel-titanium alloy arch wire has a direct relationship with the history of arch wire deformation. The orthodontic force needs to trace the deformation history of arch wire.