摇椅形弓丝配合前牙区垂直牵引矫治开时牙齿应力分布与位移趋势的研究

Photoelastic analysis of stress distribution and movement tendency of lower teeth in open bite treatment using reverse-curve arch wires with vertical elastics in anterior teeth area

目的:研究"摇椅形"弓丝配合前牙区垂直牵引矫治开时下颌牙齿的应力分布及移动趋势。方法:建立与人体物理性能相似的1∶1的全牙颌光弹模型,对模型进行临床实际应用的"摇椅形"弓丝配合前牙区垂直牵引力加载,将下颌实验模型单颗牙进行三维方向冻结切片,利用三维切力差法,计算单颗牙牙槽骨各点应力值,从而描述单颗牙牙周组织应力分布规律及运动趋势。结果:在"摇椅形"弓丝配合前牙区垂直牵引作用下,7运动趋势为整体远中移动,冠受远中向力大于根,整体龈向压低,轻微颊向移动;6整体远中移动,龈向压低,冠向远中舌向倾斜;5的移动趋势为整体远中移动,向伸长,冠向远中旋转,近中颊向远中舌向扭转;3运动趋势为向伸长,冠唇向根舌向倾斜;2的运动趋势为向伸长,冠唇向根舌向转矩。结论:"摇椅形"弓丝配合前牙区垂直牵引作用于全牙弓牙齿的移动趋势符合开的矫治机制。

Objective：To investigate the stress distribution and movement tendency of lower teeth in open bite treatment using reverse-curve arch wires with vertical elastics in anterior teeth area by three-dimensions photoelastic analysis. Methods： Photoelastical model of full teeth was established following the physical parameter and dimension of human teeth, and reverse-curve arch wires with vertical elastics in anterior teeth was applied as clinical treatment. Every freezing model-tooth was bladed by three-dimensions, the stress of every point of alveolar bone was calculated by three-dimensions shear-equation method, and the stress distribution regularity of per-tooth was analyzed to describe their moving tendency. Results： The second molar was intruded and moved to distal and buccal side and the crown was rotated distally. The first molar was intruded and moved to distal side and the crown was inclined to distal and lingual side. The second premolar was extruded and moved distally and the crown was rotated to distal side, the mesial part was rotated buccally and the distal part was rotated lingually. The canine was extruded slightly and inclined as positive torque. The lateral incisor was extruded and the crown moved labially and was inclined as positive torque. Conclusion：Using reverse-curve arch wires with vertical elastics in anterior teeth area is accordance with the mechanism of open bite treatment.