Research & Implementation Of Key Technologies For Prosthodontics Metal Substrate Crown With CAD

In the prosthodontics domain,metal crown is the important component of PFM crown, and therefore the shape and the precision is particularly is important. The traditional manufacturing process is time-consuming and over labor. With the development of computer technology, developing the computer-aided design software of metal crown have important value in practice use. Based on clinical science of stomatology and the digital model of STL file, this paper studies relevant algorithms on triangular mesh about designing metal crown. The main innovative contributions of this dissertation are as follows:Firstly, reconstructing the topology relation of the discrete surface model efficiently with the red-black tree data structure. Through the points near the real preparation line picked up interactively, this paper use the"tracking on direction"method to determine the initial contour between very two adjacent points, and optimize it to preparation line with Snake energy model. According to closed characteristics of the preparation line, using seed method, the inner surface of crown can be extracted and the border of which will be effectively optimized.This paper using offset method to create outer surface. Two offsetting algorithms are researched. One is basing on normal and the other is basing on implicit surface. How to create implicit surface equation based on radial basis functions is elaborated. After that, an improved MC algorithm and optimizing implicit triangular surface can create the high quality outer surface.Because the existing common mesh transition and mesh blend algorithm can not resolving the transition of inner and outer surface of metal crown. In the analysis of the characteristics of the border and drawing on the ideological of parameters surface, this paper present a transition algorithm which is particularly used in designing a crown. This method is fast and the mesh is smooth, high quality and can meet the medical needs.Based on the algorithms which has been researched and using VC++6.0 and HOOPS library ,this paper developed the metal crown software system. Finally ,the paper show the product which is made in alloy and designed by this software.