Comparison of Buccal versus Palatal Mini-Screw Anchorage for Maxillary Posterior Intrusion with Clear Aligners: A Finite Element Analysis

This Finite Element Analysis study evaluated the biomechanical responses associated with posterior tooth intrusion using clear aligners in conjunction with buccal and palatal mini-screw anchorage. Three-dimensional finite element models were reconstructed from cone beam computed tomography images obtained from patients without craniofacial anomalies. To assess the differential effects of buccal versus palatal attachment placement in combination with a mini-screw-supported closing coil spring, two configurations of the maxillary arch were created: Model A (right side) and Model B (left side). Biomechanical parameters—including stress distribution, patterns of tooth displacement, and anchorage stability—were systematically assessed using finite element analysis. Analysis of Model A revealed buccal crown inclination and moderate extrusion of the first premolar, whereas the first molar showed limited mesial displacement along with mild buccal tipping and extrusion. In contrast, Model B revealed palatal crown inclination of the first premolar, accompanied by buccal root torque and minor intrusion; the first molar demonstrated enhanced vertical control with palatal root torque. The incorporation of palatal mini-screw anchorage in Model A contributed to diminished stress levels and reduced tooth displacement, suggesting a tendency toward more favorable force distribution and anchorage stability under the simulated conditions. Conversely, Model B experienced increased mechanical loading and more pronounced displacement.