Research And Application On The Modeling Key Technologies For Dental Restoration

With the development of information technology, CAD/CAM technologies are gradually applied to dental medical treatment, which has greatly improved the quality and effiency of dental restoration and sped up the technology revolution in dental industry. The modeling technology of dental restoration is one of the most important and fundamental technologies of dental CAD/CAM system. Combined with the demands of dental clinic, system structure, relevant theories and key technologies are studied deeply in the dissertation and a dental modeling prototype software is developed. The main contents and achievements are as follows:1. To develop the dental modeling software, a three-layer modeling system structure is presented including theory layer, tool layer and application layer. Input models, output models and inner core models are designed for the dental modeling software in detail using the main line of data flow.2. To efficiently reconstruct the topological structure of a large number of STL(Stereolithography) data, the integrating vertex algorithm of the AVL tree based on the V-F structure is promoted to delete a large number of repeated vertexes and reduce the size of data file. Then, the associated search optimal algorithm based on virtual AVL tree is promoted to rapidly reconstruct the half-edge topological structure.3. To rebuild the tooth surface from the littery measure data, the membrane deformation algorithm based on loop subdivision is given to fit density triangle meshes to subdivision surface. The initial mesh surface is firstly simplified by applying Quadric Error Metrics. Then, the simplified triangle meshes are subdivided to improve the deformable ability. Absorbing operator is applied to"drag"the subdivision mesh surface to approximate initial density meshes. Smoothing operator is applied to guarantee the low local distortion of the triangular faces.4. To extract the preparation line on the basic tooth model, an algorithm of automatic extraction of feature line is proposed. Firstly, discrete curvature analysis for triangle meshes is done to obtain approximation curvature values. Feature regions are distinguished automatically through given curvature threshold. Secondly, the key...