不同控根附件对无托槽隐形矫治远移尖牙的影响

Influences of Different Root Control Attachments on Canine Distal Translation with Plastic Aligner

目的分析不同控根附件在无托槽隐形矫治远中移动尖牙时的控根效果及对牙周膜应力的影响。方法通过三维有限元技术,建立由4种附件(附件A:无附件;附件B:传统垂直矩形附件;附件C:1/4球形双优化附件;附件D:门拱形双优化附件)和3种载荷(载荷a:矫治器预设0.15 mm远中位移;载荷b:载荷a+对附件受力面施加30 N·mm逆时针力矩;载荷c:载荷a+对整个牙冠施加30 N·mm逆时针力矩)组成的11组模型。模拟右上颌尖牙在不同载荷无托槽隐形矫治作用下远中移动的控根效果。结果所有模型的位移模式均为远中倾斜移动。门拱形双优化附件远中移动尖牙时控根效果最佳。两组双优化附件控根效果优于传统矩形附件。添加附件对尖牙的控根效果明显优于只施加逆时针力偶。无附件时牙周膜应力主要集中于远中牙槽嵴及根尖,有附件时牙周膜应力主要集中于远中牙槽嵴。结论临床无托槽隐形矫治器在远移尖牙时,门拱形双优化附件有较强的控根效果。

Objective To study the effects of different root control attachment on root control and periodontal ligament(PDL)stress during canine distal translation in plastic aligner-based orthodontic treatment.Methods Through three-dimensional(3 D)finite element technology,11 models composed of 4 attachments and 3 kinds of loading were established.Namely,attachment A:no attachments;attachment B:traditional vertical rectangular attachment;attachment C:1/4 spherical double optimized attachment;attachment D:double optimized door arch attachment;load a:0.15 mm distal translation of the canine;b:load a+application of 30 N·mm counterclockwise torque to stress surface of the attachment;load c:load a+application of 30 N·mm counterclockwise torque to the entire crown.The root control effect of distal translation of the right maxillary canine was simulated with plastic aligner under different loads.Results Displacement modes of all models were distally tipped translation.The double optimized door arch attachment showed the optimal root control effect during canine distal translation.The root control effect for two groups of double optimized attachment was better than that of traditional rectangular attachment.The effect of adding attachments on root control of the canine was better than that of applying only counterclockwise couple.The PDL stress mainly appeared in distal alveolar ridge and root apex without attachment,while the PDL stress mainly appeared in distal alveolar ridge with attachment.Conclusions The most suitable measure to improve the effect of root control during canine distal translation is to use the double optimized door arch attachment in clinic.