Retraction Of Maxillary Anterior Teeth With Clear Aligner:A Three-dimensional Finite Element Analysis

Objective: To discuss and analyze the biomechanical characteristics of maxillary anterior teeth in different retraction movement with clear aligner.Method: 1.A bimaxillary protrusive adult female was chosen for study,whose orthodontic treatment was extraction of four first premolars.The scanned data of patient’s dentition and CBCT of patient’s maxillofacial region were taken for constructing three-dimensional model by using medical reconstruction software-Mimics 16.0.After overlapping and Boolean calculating,the initial three-dimensional model of teeth-periodontal ligament(PDL)-alveolar bone was constructed eventually.2.By using Abaqus 6.12 software to simulate clear aligner on the three-dimensional model and compare the stress and movement of maxillary incisors after three different retraction.And the three different retraction of maxillary incisors are 0.25 mm of retraction,0.1mm of retraction with 0.23 mm intrusion and 0.2mm retraction with0.15 mm intrusion.Result: 1.The three-dimensional finite element model was built,including maxilla,alveolar bone,upper dentition,periodontal ligaments(PDL),clear aligners and attachments.2.Tipping movement of maxillary incisor along with extrusion could be observed in 0.25 mm retraction of maxillary incisor,Intrusion of maxillary incisor along with tipping movement could be observed in0.1mm retraction of maxillary incisor with 0.23 mm intrusion.Bodily movement of maxillary incisor along with intrusion could be observed in 0.2mm retraction of maxillary incisor with 0.15 mm intrusion.Conclusion: Adding intrusion movement in maxillary anterior teeth retraction with clear aligner,could prevent maxillary incisors from extrusion,and decrease maxillary incisors to lingual tipping movement.Bodily movement of maxillary incisors retraction could be achieved by adding 0.2mm retraction of maxillary incisor with 0.15 mm intrusion.