上颌尖牙远中整体移动的阶段应力分析

Three-Dimensional Finite Element Analysis of Maxillary Canine During the Tooth Translation Movement

目的 在模拟整体移动的载荷条件下 ,分析上颌尖牙远中移动不同阶段的牙周支持组织的应力衰减规律。方法 通过采用有限元法建立的骨改建力学数字模型 ,模拟整体移动的加载条件 ,分析上颌尖牙移动过程中0 d、7d、14 d和 2 1d时牙周膜和牙槽骨的应力状况。结果 1在整个牙移动过程中 ,牙槽骨的应力均大于牙周膜的应力水平 ;2牙槽骨和牙周膜的应力水平从牙颈部至根中份和根尖区呈现递减趋势 ;3随着牙移动进程 ,不同部位牙周支持组织的应力衰减速率有差别 :越靠近牙槽嵴部位 ,其应力衰减的速率越快 ;反之越靠近根尖区 ,应力衰减越慢 ,至 2 1d时应力水平趋于接近。结论 临床治疗中在使用正畸力时 ,容易发生早期的牙槽嵴吸收、牙支持高度降低 ,应注意控制初始力值 ,保护牙周组织的健康。

Objective To find the characteristic of the stress distribution in the periodontal tissue during maxillary canine distal translation.Methods The model was implemented numerically by means of the 3-dimensional finite element method (FEM) and was used to simulate orthodontic tooth translation movements. The finite element model was loaded with defined force systems. And the stresses at 0,7,14, and 21 days of loaded distal force and moment in maxillary canine were calculated. Results During the whole distal translation of canine, ①the stress in alveolar bone was higher than that in peridontal ligament; ②the stresses in the cervical region were higher than those in the apical region of the alveolar bone and periodontal tissues; ③the stresses in the cervical, medium and apical regions of periodontal tissue were on the decline, and the stress in cervical region declined faster than that in apical region. On the 21st day the stresses in the cervical, medium and apical regions were similar. Conclusion The 3-D FEM analysis revealed that alveolar bone loss could be most likely to happen during the initial stage of the tooth movement, and the data from this study mihgt be helpful to orthodontists in selecting an appropriate device of force systems to control the initial loading during orthodontic treatment.