磨牙支抗曲打开咬合前牙压入力分布的有限元研究

The finite element analysis of the force system produced by the molar anchor bend

目的 对差动技术中磨牙支抗曲打开咬合所产生的力学系统进行有限元分析 ,了解磨牙支抗曲打开咬合时 ,各个牙齿在弓丝作用下的垂直向受力大小。方法 采用国内外最先进的ANSYS有限元分析软件 ,建立起国人普通型牙弓的上下颌标准弓形的三维有限元模型 ,在此基础上进一步真实地模拟临床 ,即在每个牙齿的确切位置上加载弓丝入槽后槽沟对弓丝的确切约束 ,求得各个牙齿在弓丝作用下的垂直向的瞬时受力情况。结果 上下颌的研究都发现差动技术打开咬合时 (双尖牙不入槽 ) ,首先在尖牙上产生较大的压力 (约 117g) ,大于其它简化的实验模拟和数学模型计算研究所得出的前牙压入力 ,从而更充分地解释了差动技术打开咬合的有效性 ,从而也说明差动技术在打开咬合时体现的另一差动性 :先压低尖牙 ,再压低切牙。另外 ,研究还通过对于三种不同临床情况下弓丝产生的力系统的比较 ,进一步证实 :利用磨牙支抗曲打开咬合时 ,双尖牙是否入槽对于矫治力系统产生很大的影响 ,双尖牙不入槽显著地加大了弓丝对前牙的压入力的同时也显著地减少了弓丝对磨牙的伸长力。

Objective Molar anchor bend is one of the most frequently used and efficient methods in clinic to correct the deep overbite,especially in differential technique.So studies have concentrated on the force system it produced,but all of them oversimplified the actual clinical situation and cannot provide the forces loaded on every one of the involved teeth.Further study needs to be performed to detect the force system produced by molar anchor bend.Methods The advanced ANSYS finite element analysis sofrware was used to setup the modle and the more delicate molar anchor bend was disclosed.Results When the bicuspids were not involved in the force system,the biggest intrusive force(117g of so) was loaded on the canine,much larger than previous studies and enough to counteract the extrusive force produced by the class Ⅱ elastic,furthermore,less moment and extrusive force were produced on the molar compared with the situation when the bicuspids were involved;and in the latter cases,the intrusive forces were concentrated on the bicuspids,and extrusive forces were dominated at the anterior teeth region.Conclusion Little changes on the orthodontic appliance will generate great changes in force system which bring different teeth movement.