The Three-dimensional Finite Element Analysis Of Lateral Pterygoid Muscle On The Role Of Stress Distribution Of Condyle Infracture Healing Process Of The Sagittal Fracture Of The Mandibular Condyle

Objective:To analyze the biomechanical stress distribution on sagittal fracture of the mandibular condyle in the healing when lateral pterygoid muscle pull or not, and to obtain atheoretical basis for Surgical treatment SFMC.Methods:The finite element model of mandibular and temporomandibular joint was established. The left condyle was simulated as SFMC with 0.1mm space across the condyle lengthways. The finite element model of SFMC was established. The biomechanical stress on mandibular and the left condyle were calculated when lateral pterygoid muscle pull or not with finite element analysis(FEA). There were stress distribution of condyle and articular disk surface, displacement around fracture.Results:when lateral pterygoid muscle pull: the stress and displacement of condylar free end increased in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture in type II fracture, the stress and displacement of condylar residual is relatively stable in the natural healing process. The stress of articular disc residual end decreased in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture, the displacement is relatively stable. The stress and displacement of articular disc free end increased in 4 weeks, from 4 weeks to 12 weeks to level off; The stress and displacement of condylar free end increased but residual decreased in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture in type III fracture. The stress and displacement were little changed of articular disc free end. Cut off lateral pterygoid muscle:The stress and displacement of condylar free end increased but residual decreased in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture in type II fracture. The stress and displacement of articular disc free end increased but residual decreased in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture; The stress and displacement of condylar free end increased in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture in type III fracture, the stress of condylar residual increased but the displacement decreased in 4 weeks. The stress and displacement were little changed of articular disc free end; The stress and displacement had big change of condylar residual and free end in 4 weeks, from 4 weeks to 12 weeks to level off in the natural healing process of fracture in type I fracture.Conclusions:Lateral pterygoid muscle has a great influence on the condylar stress and displacement in fracture Healing Process of the SFMC. After cut off the lateral pterygoid muscle: the stress and displacement of condylar free and residual terminal increases in the natural healing process of fracture in type II fracture; The stress increases and displacement decreases of condylar free end in the natural healing process of fracture, the stress of condylar residual on postoperative day decreases, and increases from 4 weeks to 12 week in natural healing, displacement decreases in the natural healing process of fracture in type III fracture.Objective: Measurement and 3D reconstruction of the temporomandibular joint disc using MR and Mimics 10.01 technology.Methods: Sixteen normal cases were chose and bilateral Temporomandibular joint were scanned by MR. Direction of scanning include oblique coronal, oblique sagittal and axial. All the images imported in DICOM format to the Mimics 10.01 software, measurement and 3D reconstruction of the temporomandibular joint disc by Mimics 10.01 software.Results: MR can show the anatomic structure of articular disc clearly. Sagittal images show: mandibular condylar located in the acetabulum of temporal bone, oval. The posterior band is located in the top of mandibular condyle crest, equivalent to 12-1 point orientation, the mesozone is located in the mandibular condyle crest before and after the temporal bone joint nodules. Coronary image display: articular disc is crescent, between condylar and articular fossa bony structure imaging, there is a parallel with osseous joint surface basic, overall trends in both inside and outside the, pervious to light degree between bone and soft tissue of moderate density area, the structure and condylar and acetabulum osseous joint surface between, across a similar soft tissue layer of high density area, should be the articular cartilage, joint clearance, joint fluid and other parts. Mimic software measurement result shows: 1. The joints before and after the plate overall performance for thick and thin in the middle.2. Condylar and between the inner and outer diameter of the acetabulum and inner diameter, from big to small order as follows: glenoid diameter>condylar diameter>glenoid inner diameter >condylar inner diameter>glenoid outer diameter>condylar outer diameter.3. Condylar coronary inclination for(89.98 + 1.43) °, close to the right.Conclusions: Using the MR and Mimics can measure the size of temporomandibular joint disc accurately, and provide reliable basis for clinical diagnosis and biomechanical modeling. By measuring, the posterior band is the thickest, the mesozone is the thinnest, the anterior band between them in normal temporomandibular joint disc, the total in the majority with "S" shape. Overall speaking, in each individual, there have obvious size and shape similarity between condylar and articular fossa.