Assessment of the Impact of Orthodontic Miniscrew Insertion Angle on the Stress Distribution During Intrusion of Anterior Teeth: A 3D Finite Element Analysis

This study evaluated the biomechanically optimal insertion angle for miniscrew-assisted anterior intrusion by analyzing stress in the periodontal ligament (PDL) and alveolar bone. A three-dimensional finite element model from cone-beam computed tomography (CBCT) data, comprising maxillary bone, anterior dentition, and a bonded orthodontic appliance, and segmented 0.019 × 0.025-inch stainless-steel archwire were used. Titanium miniscrews (1.4 × 6 mm) were placed at 5 mm from the alveolar crest between the lateral incisor and canine. Four insertion angulations relative to the occlusal plane (30°, 60°, 90°, and 120°) were simulated under a 90 g intrusive force. Results demonstrated that while all configurations achieved intrusion with minor labial tipping and maintained miniscrew stability, stress localization was highly angle-dependent: the 90° insertion generated the highest central incisor PDL tensile stress and maximum cortical bone Von Mises stress; the 120° insertion yielded peak canine PDL Von Mises stress and maximum root displacement; and the 60° insertion localized peak stresses within the cancellous bone and the bone–implant interface. Miniscrews remained stable in all scenarios. While all tested miniscrew angulations provided stable anchorage for upper anterior teeth intrusion, the selection of insertion angle critically influenced stress patterns within the supporting tissues.