Three-Dimensional Finite Element Analysis On The Maxillary Expansion Of Different Groups With Clear Aligner

Objective:To explore the biomechanical mechanism Expansion of middle and posterior segment of Maxillary teeth in different groups with clear aligner using Three-dimensional finite element method,The rusule provide theoretical basis for the design of clear aligner tooth movement procedures.Methods:The Cone-beam CT(CBCT)was used to scan an individual normal adult male volunteer.The three-dimensional finite element(3D-FE)model including maxillary teeth,periodontal ligament(PDL),alveolar bone and clear aligner(CA)was established by Mimics 20.0,Geomagic Studio 2013,Hypermesh14.0 software packages.Different tooth movement groups and diffenent tooth movement amount of maxillary arch expansion processes models with Clear aligner was imported into Abaqus 2018 software using non-linear contact to simulate the biomechanical process.The biomechanical process of the initial movement trend and displacement of maxillary dentition,the initial stress distribution of periodontal membrane and alveolar fossa,and the initial deformation trend of the appliance were analyzed.A total of 10 models were divided into four ABCD groups,the experimental group numbers were : A1(whole dentition 76 movement 0.2 mm)B1(half dentition 76 movement 0.1 mm)B2(half dentition 765 movement 0.1 mm)B3(half dentition7654 movement 0.1 mm)C1(half dentition 76 movement 0.2 mm)C2(half dentition 765 movement 0.2 mm)C3(half dentition 7654 movement 0.2 mm)D1(half dentition 76 movement 0.3 mm)D2(half dentition 765 movement 0.3 mm)D3(half dentition 7654 movement 0.3 mm).Results:1.The biomechanical finite element model with good geometric similarity and high simulation can be constructed by using Mimics,Geomagic Studio and Hypermesh software.This method is simple and accurate,which lays the foundation for the following experiments.2.By comparing the initial tooth movement and trend,the stress of periodontal membrane and alveolar fossa,and the initial deformation trend of the appliance in the whole dentition and half dentition models,it is found that the total displacement trend and stress of the whole dentition and half dentition are close to each other.3.Through the experimental calculation and analysis :(1)With the same amount of movement,different groups of dental arch expansion : with the increase of the number of teeth,the lip inclination displacement of central incisor and lateral incisor increased gradually;The adjacent teeth near the middle end of the group teeth have buccal inclination and instrusion,and the anterior teeth near the middle end have palatal inclination and extension.(2)Different movement,the same group of dental arch expansion : tooth initial maximum displacement increases with the increase of movement.(3)The equivalent stress of periodontal ligament in the three groups of BCD was concentrated in the neck and root tip,and the equivalent stress of alveolar bone was concentrated in the neck and root bifurcation area.The stress distribution was basically consistent with the rule of tooth movement,except for B1,C1 and D1 groups.(4)The whole clear aligner showed a downward dislocation trend.The central incisor and lateral incisor rotated downward to the labial side.From canine to second molar,the central incisor rotated downward to the palatal side.Conclusions:1.The maxillary arch expansion with clear aligner is affected by different movement and different tooth movement design,and its mechanism is worth further exploring.2.The deformation trend of the initial occlusal rotation dislocation of the clear aligner,and the anchorage teeth also moved,suggesting that attention should be paid to strengthening the retention and anchorage design in clinical practice.