Three-dimensional Nonlinear Finite Element Analysis Of Maxillarylateral Incisor Torque Force By Invisible Appliance

Part1Set up a finite element model composed of alveolar bone, maxillary dentition and invisible appliance.Objective:To set up a three-dimensional finite element composed of maxillary dentition, alvealar bone, periodontal ligament and invisible appliance, the nonlinear contact analysis was used to calculate the stress distribution in periodontal ligament and alveolar bone when the invisible appliance was inserted to the dentition. This will provide for the study of the mechanism of invisible appliance.Methods:We acquire a DICOM by using spiral CT scanning for volunteers’maxillary dentition and alveolar bone and set up a3geometric model composed of the upper jaw,crowns and root by using Mimics software. Then we can rebuilt teeth and alveolar bone. We can gain the finite element model of teeth and surrounding tissues by Hypermesh10.0software.Results:A three-dimensional finite model composed of the invisible appliance, maxillary dentition, alveolar bone and periodontal ligament was set up, and the nonlinear analysis was successful.Conclusion: We first set up a whole three-dimensional finite element model composed of the invisible appliance, maxillary dentition, alveolar bone and periodontal ligament by Hypermesh10.0software. The contact nonlinear calculation simulated process that a invisible appliance were insert to the dentition. The model provides a good platform for further analyzing the mechanism of invisible appliance.Part2Three-dimensional nonlinear finite element analysis of maxillary lateral incisor torque force by invisible appliance.Objective:This study adopts three-dimensional finite element method to discuss the stress distribution of the upper indsors and supporting tissues and the teeth movement trend. These provide biomechanical basis for clinical treatments to master and use invisible appliance.Methods:Using the first part of the finite element model by imposing different levels of force on the teeth, gingival couple and tongue, orthodontic force range between100～300and analyze teeth movement type, stress distribution and displacement of each group. The group are as follows:Simulation techniques without brackets invisible orthodontic appliance load in incisor labial cervical1/3vertical loads a set of orthodontic force strength is about300g, through no bracket deformation0.3mm achieve invisible orthodontic appliances; they were distribution in the neck of the crown1/3; simultaneously simulate invisible appliance in clinical crown lip lateral side1/3load a set of forces is approximately100g,300g orthodontic force, uniform teeth cut in1/3part. Group A:meanwhile incisor incisal1/3loading100g orthodontic force, obtain through deformation0.1mm; group B: at the same time cutting side a third loading force,200g correction without braces contact and correcting the shape change of0.20mm; group C:at the same time cutting side a third loading force,300g correction without braces contact and correcting the shape change of0.3mm; group D (control group) in cervical1/3vertical load only a set of power is about300g of malocclusion, cut side without loading force.Results:Periodontal membrane group C in terms of stress, the maximum principal stress of the highest, the Von mises stress of periodontal membrane group A (equivalent stress) is greater than B and C group, but less than the control group. Group B minimum principal stress and the equivalent stress is minimal. The highest overall stress level of group C, group B stress level is higher, A group of stress level the lowest. In addition to the group B each apex and tooth neck stress concentration is more obvious. Group B uniform stress distribution. In terms of displacement, group B is closer to the whole movement. The other three groups are tilting movement.Conclusion:(1) The use of stealth correctional implement reasonable strength way can achieve the maxillary anterior teeth even accused of root movement as a whole.(2) Experimental group B X direction is close to the overall displacement, uniform stress distribution, root stress concentration.(3) Experimental group B rotation center is located in the tooth root infinity, the rotation center is located in the center of the impedance of the tooth root.(4) Experimental group B biomechanics applying pressure effect is better than the other three groups.