Evaluation of Stress, Strain, and Three Dimensional Tooth Movement During Molar Distalization Using Different Attachments With Clear Aligners: A Finite Element Analysis

Objective: The present study aims to evaluate the stress, strain, and three-dimensional (3D) tooth movement during molar distalization using various attachment designs with clear aligners through finite element analysis (FEA). The study further seeks to identify how different attachment geometries influence biomechanical performance, efficiency of distalization, and overall control of tooth movement. MaterialsandMethods: A 3D geometric model of the maxilla, teeth, periodontal ligament (PDL), and clear aligner was generated using cone-beam computed tomography (CBCT) data of a patient requiring molar distalization. The models incorporated four configurations: horizontal, vertical, and elliptical attachments, and one without attachment. Each model was subjected to a standardized 10 N distalizing force in ANSYS Workbench R2. Stress, strain, and displacement patterns were evaluated across the X (transverse), Y (sagittal), and Z (vertical) planes. Results: The vertical rectangular attachment produced the highest von Mises stress (10.75 MPa) and strain (0.00353 mm/mm), indicating effective distalization but with an increased risk of uncontrolled tipping. The elliptical attachment demonstrated moderate stress (8.48 MPa) and lower strain (0.00246 mm/mm), offering better control and a more uniform force distribution. The horizontal attachment produced intermediate outcomes (10.08 MPa), while the no-attachment model exhibited minimal stress (0.50 MPa) and negligible movement. Displacement was greatest along the Y-axis (distal direction) for the vertical attachment, whereas the elliptical attachment showed enhanced intrusion and bodily movement characteristics. Conclusion: Attachment design has a profound influence on the biomechanical response of teeth under clear aligner therapy. The elliptical attachment design provided the most balanced stress distribution and controlled movement, while vertical attachments, though effective in distalization, required auxiliary measures to minimize tipping. These findings reinforce the significance of precision attachment design in optimizing clinical outcomes in clear aligner–based orthodontic treatments.