Biomechanical effects of various occlusal conditions and orthodontic force levels on mandibular canine distalization: a finite element analysis

Mandibular canine distalization plays a key role in orthodontic treatment planning, particularly in cases involving premolar extraction. A three-dimensional symmetric finite element analysis (FEA) model with bilinear periodontal ligament (PDL) properties to evaluate the combined effects of five occlusal conditions—intercuspal position (ICP), incisal clench (INC), right unilateral molar clench (RMOL), right group function (RGF), and no occlusion—and three orthodontic force levels (0.98, 1.47, and 1.96 N) on PDL biomechanics. The effects were assessed by measuring hydrostatic stress as an indicator of capillary perfusion and maximum principal strain as a mechanical signal for tissue deformation and bone remodeling stimulus. According to the FEA results, a moderate force of 1.47 N produced a relatively favorable biomechanical response under nonocclusal conditions. Intercuspal position and incisal clench conditions were associated with elevated stress and strain concentrations in the PDL. The right unilateral molar clench condition preserved load-induced bilateral symmetry, whereas the right group function condition resulted in differential left–right biomechanical responses in the PDL under asymmetric occlusal loading conditions. These findings indicate that occlusal loading is a key mechanical factor influencing the biomechanical environment during orthodontic tooth movement. FEA simulations that consider occlusal loading can provide comparative biomechanical insights that can guide the selection of orthodontic forces and identification of mechanical risks.