Deformation Research Of Feature-based Fixed Denture Mesh Model

With the widely use of computer information technology and CAD/CAM technology, dental restoration area are undergoing a revolutionary change. Th e traditional way to make tooth restoration is through wearing tooth restoration repeatedly, it can not meet the current fast-paced lifestyle. During the process of tooth restoration, CAD design is a limit. And the main work of CAD is the deformation of tooth model. As a result, this paper is mainly to research the deformation of feature-based denture mesh model.The occlusal surface of molar has a very complex surface, and different people have different tooth. However, the same position tooth of different people has some the common feature, which provides a limit for the CAD design of tooth. So the first step is to analyze the feature of the tooth and define the feature points and feature lines.According to the definition of feature points, this paper through searching all points of the tooth model to get the cusp, the nest and the protrusion of the tooth model. For the feature, this paper use the definition of feature lines to get and display, and it use about 385 second to compute. It has serious delay. Then this paper studies the algorithm again and find new search algorithm, it use only about 0.29 second. This speed can meet the command of software operation.Considering the feature and the principle of tooth restoration, this paper then does the tooth model global deformation. Before the global deformation, this paper use interactive way to shift or rotate the two tooth m odel to the nearly same position. Here the translation and rotation of the model is refer to only the model, not include the coordinate. In other words, it is not the shift or rotation of the view. Then use the RBF to do the global deformation of the tooth model.After the global deformation, the result may appear some difference. So this paper needs to do some local deformation to adjust the tooth model. Local deformation mainly refers to add, smooth and subtract. As a result, this paper need to research the algorithm of the deformation add, smooth and subtract. At last, considering the perfection of the software, this paper set local deformation button for the two models. And complete the function and design the interface of the software and write the code.