Reconstruct The Three-Dimensional Finite Element Model Of Retrusional Mandible With Mandibular Dentition

Objective:To explore the method of use the reverse engineering technique to reconstructs the three-dimensional finite element model of Retrusional Mandible with Mandibular dentition,which is used to overload functional appliance treated mandibular retrusion.Materials and method:Select an orthodontic patient in growth pattern, which conserved all dentulous and is normal body growth and mandibular retrusion. The molar relationship is Remote in the neutral and arcus dentalis form is symmetry. The CVS is in stageⅡ-Ⅲ. Wits value is 5mm.16-row multislice Spiral CT scanner which is made by Philips in Netherlands was used to scan the patient. The scanning condition is 120KV,400mA,1500mS, the hor zontal distinguish is 1024×1024.The scan plane is parallel lines of Frankfort Horizontal Plane.The scan thickness is 0.5mm.1812-D pictures was procured, and put out with DICOM file, which is burning by CD-COM in the CT scanner.Input the DICOM files to the Mimics8.1 software,which is made by Materia-lise in Belgium. Then select suitable threshold 405 of CT gray value to rev-erse the model of mandible.The profile line function was used to measure the grey scale on the bound-ary of amelogenesis. The grey scale above 1676 was extracted using the grey valve scale selection. The additional noise was eliminated with the method that is the same to extract the mandible, the high quality 3D model of the mandible and lower denture was obtained. The integrity of the model was verified and exported in STL format, the file extension is.STL.The STL data model was optimized in Geomagic to get a close match with the tooth model to be analyzed. The obtained iges model could be imported into HyperMesh to get a mesh.The exported igs file was imported into the FEM preprocessor HyperMesh, a 10 nodes tetrahedron was chosen for the mesh.. The ccd batch file of ANSYS was exported. The material properties was assigned to the mode in ANSYS.Results:The fine 3D finte element analysis model of Retrusional Mandible with Mandibular Dentition was constructed successfully.After 3D meshing, the model has 37475 nodes and 194671 elements.Conclusion:1. The CT image of a real patient was employed, a high precision scan was achived, the thickness is 0.5mm. the reliability of the data source was guaranteed. The Dicom file was imported into Mimics, which reduced the loss and error during the patient information conversion. The proposed model is close to the tooth in reality.2. The precision of the model was enhanced using the reverse engineering software. The surface optimization and smooth technology simplified the modeling significantly, which can satisfy the need of personalized modeling in the future.3. A 3D FEM model was proposed for mandible, which offers the foundation for the future work. It is also an investigation of high speed and high precision modeling method for the biomechanics, makes contribution to the personal modeling technique.