Finite Element Analysis Of Mandibular Incisor Retraction In Clear Aligners

Establish a finite element model to investigate the biomechanical effects of stepwise retraction of mandibular anterior teeth using clear aligners under different orthodontic designs. The finite element model was established and divided into three groups:Model A: retracted mandibular incisor 0.2mm; Model B: model A and intruded 0.10mm; Model C: model C and the root lingual torque of 5°was added. Conduct preprocessing on the model to simulate various retraction methods for mandibular incisor and analyze effects. In all groups, the incisors exhibited lingual tipping tendencies, while the canines and posterior teeth demonstrated mesial inclination. The addition of intrusion and torque control reduced lingual tipping of incisors, though bodily movement was not achieved. Group A showed the most pronounced tipping tendency, whereas Group C displayed the least. Maximum stress in the periodontal ligament was concentrated at the cervical regions across all groups. Stress magnitudes followed this hierarchy: lateral incisors > central incisors > canines > second premolars > first molars > second molars. Group C exhibited the highest stress levels, while Group A demonstrated the lowest. In cases, incisors exhibited lingual tipping with extrusion, while canines and posterior teeth demonstrated mesial inclination when torque compensation was absent. The incorporation of intrusion mechanics and torque compensation significantly enhanced incisor torque control, effectively counteracting undesirable crown displacement. Increasing intrusion magnitude, torque adjustment proportionally elevated anterior dental stress. To mitigate root resorption risks in incisors, clinicians should implement reduced step size and distributed force application .