Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; University of Chinese Academy of Sciences, Beijing, China.
Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Am J Orthod Dentofacial Orthop. 2023 Aug;164(2):183-193. doi: 10.1016/j.ajodo.2022.11.019. Epub 2023 Mar 27.
In invisible orthodontics, attachments are used with aligners to better control tooth movement. However, to what extent the geometry of the attachment can affect the biomechanical properties of the aligner is unknown. This study aimed to determine the biomechanical effect of attachment geometry on orthodontic force and moment using 3-dimensional finite element analysis.
A 3-dimensional model of mandibular teeth, periodontal ligaments, and the bone complex was employed. Rectangular attachments with systematic size variations were applied to the model with corresponding aligners. Fifteen pairs were created to move the lateral incisor, canine, first premolar, and second molar mesially for 0.15 mm, respectively. The resulting orthodontic forces and moments were analyzed to compare the effect of attachment size.
Expansion in the attachment size showed a continuous increase in force and moment. Considering the attachment size, the moment increased more than the force, resulting in a slightly higher moment-to-force ratio. Expanding the length, width, or thickness of the rectangular attachment by 0.50 mm increases the force and moment up to 23 cN and 244 cN-mm, respectively. The force direction was closer to the desired movement direction with larger attachment sizes.
Based on the experimental results, the constructed model successfully simulates the effect of the size of attachments. The larger the size of the attachment, the greater the force and moment, and the better the force direction. The appropriate force and moment for a particular clinical patient can be obtained by choosing the right attachment size.
在隐形正畸中，附件与矫正器一起使用，以更好地控制牙齿移动。然而，附件的几何形状在何种程度上影响矫正器的生物力学特性尚不清楚。本研究旨在通过三维有限元分析确定附件几何形状对正畸力和力矩的生物力学影响。
采用下颌牙齿、牙周韧带和骨复合体的三维模型。在模型上应用具有系统尺寸变化的矩形附件，并相应地使用矫正器。创建了 15 对，分别将侧切牙、尖牙、第一前磨牙和第二磨牙向近中移动 0.15mm。分析产生的正畸力和力矩，以比较附件尺寸的影响。
附件尺寸的扩展显示出力和力矩的连续增加。考虑到附件尺寸，力矩的增加超过了力，导致力矩与力的比值略高。将矩形附件的长度、宽度或厚度扩大 0.50mm，力和力矩分别增加到 23cN 和 244cN-mm。较大的附件尺寸使力的方向更接近预期的运动方向。
根据实验结果，所构建的模型成功模拟了附件尺寸的影响。附件尺寸越大，力和力矩越大，力的方向越好。通过选择合适的附件尺寸，可以获得特定临床患者所需的适当力和力矩。
