The Establishment Of Three-dimensional Finite Element Stress Analysis Models Of Tmj With Skeletal Class ? Malocclusion Pre-operation And Post-operation

Objective: Constructed FE models of a patient with skeletal Class ? malocclusionbefore orthodontic treatment(T1),after preoperative orthodontics(T2),after BSSRO(T3)and postoperative orthodontic treatment(T4)by using finite element method,the objective of the experiment was to investigate the stress distribution characteristics of TMJ in the patient with skeletal Class ? malocclusion during closed jaw clenching and opening,and analyze the variation trend of the TMJ stress during orthognathic surgical treatment.Method: 1.A 26-year old male patient with skeletal Class ? malocclusion which the SNA angle was 81.7°,the SNBangle was 91.9° and the ANB angle was-10.1°was selected.The patient was diagnosed as simple bony mandibular protrusion with complete dentition,and had no history of TMD or orthodontic treatment,needed orthodontic-orthognathic treatment.The64-slice CT were used to obtain the DICOM format image data,then importing the data into Mimics 17.0 software.After separating the upper and lower jaw bone,masticatory muscle,articular disk,glenoid fossa,condyle and other structures,a three-dimensional STL model were established.Create a temporomandibular joint disk structure in Creo 3.0 software used the positive design method and export it to STL format.After smoothing and substantiating the STL model with Geomagic software,the CAD model of the temporal bone,mandible and articular disk was construted.2.Based on the CAD models,set the interface types,contact types,friction coefficients and material properties of all components in the four models in Hypermesh 10.0 used the inverted design method.Imported and analyzed the meshed models with finite element analyzed software Abaqus 6.13 by setting the boundary conditions and the loading conditions according to the physical cross-sectional area and the strength of different muscles.Result: Succeeded in constructing FE models ofTMJ,jaws and dentitions in the patient.And the Von Mises stress nephograms of TMJs and the maximum Von Mises stress of the components of the TMJs of skeletal Class ? malocclusion were obtained before orthodontic treatment,after decompensation,BSSRO and postoperative orthodontic treatment.Conclusion:(1)On the basis of CT data,it was feasible to construct high quality FE models through general application of Mimics 17.0 ? Creo 3.0 ?Geomagic Studio12.0?Hypermesh 10.0?Abaqus 6.13.Orthognathic surgery can change the stress distribution of bilateral temporomandibular joints in the patient with skeletal Class ? malocclusion.It can directly reflect the variation trend of TMJ stress during orthognathic surgery,provide a theoretical basis for clinical treatment,and have certain reference value.(2)The stress of bilateralcondylar tends to equalize after BSSRO surgery,and recover to disequilibrium after postoperative orthodontic.The stress of the bilateral articular disk tends to equalize after orthognathic surgery.