三种加力方式下近中移动下颌磨牙的有限元分析OA

Objective:To compare the biomechanical effects of three orthodontic force application modes on the me-sial movement of the mandibular first molar using three-dimensional finite element analysis.Methods:A three-dimensional fi-nite element model comprising the mandibular first molar(two-rooted),periodontal ligament,alveolar bone,and orthodontic appliance was constructed.Three loading conditions were simulated to induce mesial movement:①buccal force(1.5 N),②lingual force(1.5 N),③bilateral buccal-lingual forces(0.75 N each).The displacement tendency of the tooth and the prin-cipal stress distribution in the periodontal ligament were analyzed for each condition.Results:Under all three loading modes,the mandibular first molar exhibited mesial tipping movement,characterized by distal extrusion and mesial intrusion.Both uni-lateral buccal(1.5 N)and lingual(1.5 N)force applications induced a certain degree of undesirable rotation,accompanied by uneven principal stress distribution in the periodontal ligament.In contrast,bilateral force application(0.75 N each)substan-tially reduced rotation and yielded a more uniform stress pattern.The magnitude of tipping angulation was ranked as follows:buccal force(1.5 N)at 0.0392°>lingual force(1.5 N)at 0.0386°>bilateral forces(0.75 N each)at 0.0374°.Conclusion:Bilateral buccal-lingual force application(0.75 N each)effectively counteracts unfavorable buccolingual moments,enabling more controlled tooth displacement,reduced tipping,and a more homogeneous stress distribution within the periodontal liga-ment.This loading strategy approaches bodily movement and is more favorable for periodontal tissue health.