The Effect of Biomechanical Loading Parameters on the Stress and Strain Behavior of Orthodontic Mini-Implants: A Finite Element Study

Background/Objectives: This study evaluated the influence of key biomechanical parameters—orthodontic force magnitude, loading direction, and insertion depth—on stress and strain distribution in orthodontic mini-implants using three-dimensional finite element analysis (FEM). Methods: A three-dimensional model of a titanium orthodontic mini-implant inserted into a mandibular bone segment was developed and analyzed under varying force magnitudes (1–10 N), loading directions (30°, 45°, and 60°), and insertion depths (2–4 mm). Cortical and cancellous bone components were included, and static loading conditions were applied using simplified, linear elastic material assumptions. Results: Stress and strain levels increased with higher force magnitudes, with implant stresses approaching critical values at loads above 9 N. Cortical bone stresses remained within physiological limits, whereas cancellous bone exceeded the microdamage strain threshold at forces greater than 3 N. A 60° loading direction reduced implant bending and strain, while deeper insertion significantly decreased strain and displacement, indicating improved primary stability. Conclusions: Within the limits of this computational model, optimal mechanical behavior was observed under 1–3 N forces, a 60° loading direction, and a 2–4 mm insertion depth. Loads above 9 N approached fatigue and interfacial risk. These findings provide computational insight into the biomechanical behavior of orthodontic mini-implants under the modeled conditions.