Finite Element Nonlinear Analysis Of The Gap Of Interproximal Enamel Reduction Closed By Clear Aligner

Objective:Establishing the overall three-dimensional model of the square crown type maxillary,maxillary anterior teeth,periodontal ligament,and clear aligner.The simulated clear aligner closes the adjacent glazing gap of the maxillary anterior teeth,and nonlinear analyzes the stress and strain of the periodontal tissue and the displacement trend and displacement of the teeth when the gap of Interproximal enamel reduction is closed.To provide scientific guidance and theoretical basis for orthodontics clinical application of interproximal enamel reduction technology in invisible orthodontics.Method:Part Ⅰ:Square round crown teeth with sharp alveolar crests and narrow alveolar space.Therefore,patients with a square crown type are treated with interproximal enamel reduction treatment of the maxillary anterior teeth.The thickness of normal teeth adjacent enamel is 0.75～1.25mm,and the maxim um movement of the teeth in each step of the clear aligner is 0.20～0.33mm.I n this study,the enamel is removed by 0.15mm in the near and far sides of e ach tooth,and the glaze is obtained after the patient’s informed consent.The CBCT stores the captured CBCT data in DICOM format and applies it to MI MICS modeling.The mechanical analysis software is ANSYS finite element an alysis software.Three-dimensional finite element model of three-dimensional rec onstruction of maxillary anterior teeth,upper anterior teeth periodontal ligament,alveolar bone and maxillary anterior clear aligner.Part Ⅱ:The finite element model established in the second part of the experiment was analyzed by using ANSYS software for three-dimensional finite element nonlinear analysis.The stress distribution of periodontal ligament and alveolar bone,as well as the displacement trend and displacement amount of teeth were studied when the clear aligner closed the adjacent enamel removal gap.The above results of the clear aligner closing the Interproximal enamel reduction gap were analyzed.Results:1.A three-dimensional finite element model including the maxillary anterior dentition,alveolar bone,periodontal ligament and upper anterior clear aligner was established,which consisted of 7901 77 units and 140409 nodes2.When the clear aligner is located on the tooth,the equivalent stress distribu-tion of the periodontal ligament is mainly concentrated on the left upper canine,the right upper canine periodontal membrane lip surface and the distal middle tooth neck,and the left upper incisor periodontal ligament lip surface.The neck 1/3,the central incisors on both sides of the periodontal ligament lip apical 1/3.The maximum stress is mainly concentrated in the left upper canine,the right upper canine periodontal ligament and the distal neck 1/3,the left upper incisor periodontal membrane lip neck 1/3,and the right upper cuspidal side,both incisors the lateral neck is 1/3 of the lateral neck,and the rest of the stress distribution is uniform.The minimum stress mainly concentrates on the proximal and distal mesothelial neck of the periodontal ligament,and the bilateral canine and lateral gingival side,and the mid-cut gingival lateral periodontal membrane 1/3 in the middleIn the process of closing the gap,the roots of the central incisors have a near-middle movement.The canines are characterized by the proximal movement of the crown,the roots moving in the distance,the teeth moving in a tilting manner,and the sagittal teeth appearing as a The lip moves,and the canine appears as a crown moving toward the lip,and the tooth moves toward the moving torque.In the vertical direction,the teeth have a tendency to be depressed.Conclusions:1.Using CBCT scanning technology to obtain the modeling data basis,save the data in DICOM format and import it into Mimics to obtain the geometric model of maxillary anterior dentition,alveolar bone,periodontal ligament and clear aligner,and use AN SYS software for 3D reconstruction and Nonlinear contact analysis,the model has high similarity with the organism,and the nonlinear analysis results are more realistic and reliable,providing theoretical guidance for the clinical use of invisible orthodontic techniques.2.When the clear aligner closes the gap of Interproximal enamel reduction,there is no obvious stress concentration area in the periodontal ligament of the maxillary 6 anterior teeth.The periodontal membrane neck stress is higher than the root and apical 1/3.The distal mid-surface stress of the canine is relatively large.3.Close the adjacent deglaze gap the maxillary 6 anterior teeth all showed proximal middle and labial movement,accompanied by gingival depression,and the displacement mode was inclined movement.