隐形矫正中不同附件对下颌尖牙唇舌向平移移动的影响

Effect of Different Attachment with Aligner in Mandibular Canine's Labial-Lingual Direction Translation

评价隐形矫正中不同的隐形矫正附件对下颌尖牙唇舌向平移移动的影响。应用三维CT扫描技术及Mimics,Geomagic Studio等软件通过三维逆向建模方法建立下颌的三维模型。使用Solidworks软件建立了12个不同的隐形矫正牙齿黏贴附件的模型。使用建立的模型在ABAQUS软件中应用有限单元方法,模拟在没有附件辅助以及有12种不同的附件辅助下,下颌尖牙的唇舌向平移移动0.25 mm。应用尖牙牙冠顶端与牙根尖端初始位移比值的绝对值Rcr来衡量尖牙旋转中心的位置,在没有附件的算例中Rcr值为2.902,在有附件的算例中Rcr均大于2.902。Rcr在4个整体附件的平均值为1.57,在半体附件中的平均值为2.25。当附件为半体附件时,尖牙的移动趋势更接近平移。尖牙牙周膜最大von Mises应力在没有附件时为1.077 MPa,在有附件的算例中最大的应力值为1.129 MPa,相对于没有附件时仅增加4.83%。水平椭圆体附件上最大的von Mises应力值可高达245.1 MPa。研究得出结论:黏贴附件有助于尖牙的整体平移移动;并不是大体积或面积的附件更有助于尖牙的平移移动;半体附件对于促进尖牙的平移移动更有效;最合适该次矫正治疗的附件是左半四面体附件。

The aim of this work is to evaluate the influence of attachments on mandibular canine’s translation movement in labial-lingual direction with Invisalign. The three-dimensional CT scan technology accompanied with modeling software of Mimics and Geomagic Studio were used to model the mandibular tissues. Twelve different attachments used to assist the orthodontic tooth movement were built by Solidworks software. The obtained mandibular and attachment models were imported into ABAQUS software to build the finite element model. Thirteen orthodontic treatment simulations that aimed to move the mandibular canine from labial to lingual side 0. 25 mm were operated in this study. Twelve simulations were operated with 12 different attachments,and one treatment simulation without attachment. The absolute value of the ratio of the maximum displacement in crown apical and root apex Rcrwere used to evaluate the position of the canine’s rotation center. In the simulation case without attachment,the value of Rcrwas 2. 902,and the Rcrvalue in other simulation cases with attachments were all greater than 2. 902. The Rcraverage value was 1. 57 in oval and rectangula attachments, and 2. 25 in other 8 semi-body attachment cases. The canine moved more like translation when the attachment was semi-body type. In the simulation case without attachment,the maximumvon Mises stress in canine’s periodontal ligament was 1. 077 MPa. In other 12 simulations with attachments,the maximum von Mises stress in canine’s periodontal ligament was 1. 129 MPa,only increased by 4. 83%when compared with 1. 077 MPa. The maximum von Mises stress value in 12 attachments was 245. 1 MPa in oval horizontal attachment. Attachments are helpful to the canine’s translation movement. The attachments with large volume and area are not the most efficient. The most appropriate attachment in this orthodontic treatment was semi-tet left.