Angle Orthod. 2023 Sep 1;93(5):566-571. doi: 10.2319/120121-879.1.
To clarify the effect of attachment types on bodily movement of the maxillary canine in aligner orthodontics.
Using an aligner, the canine was moved bodily by 0.1 mm distally as a target position. Orthodontic tooth movement was simulated using the finite element method (FEM). The alveolar socket was displaced in the same manner as the initial movement caused by elastic deformation of the periodontal ligament. First, the initial movement was calculated, and then the alveolar socket was displaced in the same direction and with the same magnitude as the initial movement. These calculations were repeated to move the teeth after placement of the aligner. The teeth and the alveolar bone were assumed to be rigid bodies. A FEM model of the aligner was made based on the crown surfaces. The thickness of the aligner was 0.45 mm, and its Young's modulus was 2 GPa. Three types of attachments-semicircular couple, vertical rectangular, and horizontal rectangular-were placed on the canine crown.
Regardless of the type of attachment, upon placement of the aligner on the dentition the crown of the canine moved to the target position, while the apex hardly moved. That is, the canine tipped and rotated. After repeating the calculation, the canine became upright and moved bodily regardless of the attachment type. In the aligner without an attachment, the canine did not become upright.
There was almost no difference among attachment types in terms of achieving bodily movement of the canine.
阐明附着体类型对上颌尖牙在直丝弓矫治器中的整体牙移动的影响。
使用直丝弓矫治器，将尖牙整体远中移动 0.1mm 作为目标位置。采用有限元法（FEM）模拟正畸牙齿移动。牙槽骨以与牙周韧带弹性变形引起的初始移动相同的方式移位。首先计算初始移动，然后以与初始移动相同的方向和大小使牙槽骨移位。在放置直丝弓矫治器后，重复这些计算以移动牙齿。牙齿和牙槽骨被假设为刚体。根据牙冠表面制作了直丝弓矫治器的有限元模型。直丝弓矫治器的厚度为 0.45mm，其杨氏模量为 2GPa。在尖牙冠上放置了三种附着体-半圆形偶联体、垂直矩形体和水平矩形体。
无论附着体类型如何，在将直丝弓矫治器放置在牙列上后，尖牙的牙冠移动到目标位置，而根尖几乎不动。也就是说，尖牙倾斜并旋转。重复计算后，无论附着体类型如何，尖牙都变得直立并整体移动。在没有附着体的直丝弓矫治器中，尖牙没有变直。
在实现尖牙整体移动方面，附着体类型之间几乎没有差异。
