Finite Element Study of Upper Molar Distalization Using a Vertical Beveled Rectangular Attachment: Influence of Buccal Surface Positioning

Background: Molar distalization in adult patients using clear aligners remains a biomechanical challenge, particularly regarding the efficiency of force transmission and the control of secondary movements. Attachment positioning may significantly influence tooth movement. Methods: Three 3D finite element models of an upper first molar with a 1 mm PET-G aligner were developed, differing only in the mesial, central or distal placement of a vertical beveled rectangular attachment. Dental displacement, contact forces and Periodontal Ligament (PDL) stress were evaluated using Autodesk Fusion FEA. Results: Central attachment placement produced the greatest distal displacement (0.314 mm), while mesial placement generated the lowest PDL stress (0.150 MPa) despite slightly higher contact force (1.2 N). All models exhibited ~2° coronal tipping. Conclusions: Attachment position influences movement magnitude and biomechanical efficiency. Mesial placement may optimize stress distribution, while Autodesk Fusion provides an accessible platform for digital orthodontic biomechanical analysis.