[A primary construction of the 3D finite element model for fixed edgewise appliance].

PURPOSE: To construct a three-dimensional finite element model (3D-FEM) of the fixed appliance for mechanical analysis. METHODS: The figures of the brackets and the edgewise wire were constructed at the platform of powerSHAPE3040, based on a male's figures of mandibular dentition and alveolar bone. First, the bracket slot center plane (H plane) was lined, which was 4.3mm under the mesial buccal cusp of the 2nd molar and parallel to the XY plane. The point that each tooth's axis of buccal surface (line A) crossed the H plane was at the bracket's center (point O). Second, on the basis of H plane, line A, and point O, 0.018 inchx0.025 inch brackets were constructed on the teeth. All the slots were on the H plane.Then, according to the brackets' slots, plane f was gotten, which went through every slot smoothly and was perpendicular to the XY plane. At the base of slots' basal wall and gingival wall, the 0.016 inchx0.022 inch wire was constructed on the plane f. The figures of edgewise wire, teeth, alveolar bone, and brackets were transferred to ANSYS5.5 system in the IGES format. The teeth, periodontal membrane (PDM), alveolar bone, and brackets were broken down to 4-node tetrahedron element. The 10-node tetrahedron element was chosen to make the model of edgewise wire. RESULTS: The 3D-FEM of the brackets with teeth, PDM, alveolar, and the edgewise wire about the mandible were obtained. This kind of bracket was torqued slot bracket, which is similar to the preadjusted appliance. The edgewise wire was not as same as catenary curve or parabola completely. There were inset and offset on the wire following the dentition model. When the plain edgewise wire was inserted in the brackets, there was no force between the wire and brackets. If the wire was deformed as designed, the action could be analyzed. CONCLUSION: 3D mechanical analysis about the fixed appliance could be done on the model.

[The establishment of 3D geometry model element for dentition defect restoration].

OBJECTIVE: To establish the library including all elements for the restoration of removable partial dentition defect. METHODS: To design and reconstruct every element that could be used to build up 3D geometry stimulation for any kind of restoration. The restoration made up of elements could be edited and changed easily for proper dentition defect. And the different restoration for the same defect can be got easily. RESULTS: Established the library of all elements for restoration of removable partial dentition defect. CONCLUSION: Established the elements library. It avoided the much work repeated and improved efficiency.The elements were the important base works for the further research on dentition defect restoration and instruction system.

[The application of 3D geometric modular element for the removable partial denture].

OBJECTIVE: To discuss the application way for element library of dentition and the removable partial denture. METHODS: With the help of some software, such as PRO/E, POWERSHAPE, etc, design the content and structure of the element libraries reasonably, and discussed the efficiency way of usage. RESULTS: We can use the element libraries by the way of "import-edit",and the way of "element group". CONCLUSION: The structure of the element libraries is reasonable and can run effectively.