Comparison of Different Clear Aligner Attachment Positions on Maxillary Posterior Teeth Intrusion with Buccal and Palatal Mini-Screw Anchorage System: A Finite Element Study

Objective This study evaluates the effects of intrusion of the maxillary posterior teeth by the use of clear aligner (CA) with buccal and palatal mini-screw anchorage system. Methods Cone-beam computed tomography images of a male patient with a skeletal Class I without any craniofacial anomalies were selected. The maxillary arch was divided into two symmetric sections Model A (right side) and Model B (left side) to compare the effect of buccal and palatal attachment placements using a mini-screw-supported closing coil spring. Finite element analysis (FEA) will assess stress distribution, displacement and mechanical efficiency during posterior teeth intrusion with different attachment positions. Results In Model A, the first premolar showed a buccal crown tipping and mild extrusion; the second premolar had similar displacement but with a mild vertical eruption. In Model B, the first premolar exhibited palatal crown tipping, buccally rooted torque and slight intrusion; the second premolar presented with a palatal drift, with less distalization. The first molar in Model A showed minimal mesial movement with a slight buccal crown tipping and extrusion. In Model B the first molar had better intrusion control with palatal root torque due to buccal anchorage. Conclusion In Model A the palatal screw experienced significantly less stress with minimal displacement. Indicating that in Model A provided a controlled distal tipping, palatal root movement and anterior intrusion, with more efficient force redirection with lower stress and superior anchorage stability. While in Model B absorbed much higher loads and showed greater displacement.