Research And Implementation Of Dental Treat CAD Technologies In Invisible Orthodontic System

Compared to the traditional fixed appliances with wires, bands, and brackets,the clear plastic overlay appliances are more beautiful, more comfortable and easier to clean. The invisible orthodontic system makes it much easier for orthodontists to offer patients who requiring full mouth orthodontic treatment a series of clear plastic overlays. Combined with the demands of orthodontic clinic and aimed to realize the function of dental treat in invisible orthodontic system, relevant theories and technologies are studied in the dissertation and the function of dental treat is developed. The main contents and achievements are as fellows:Firstly, this paper presents a semi-automated method for detecting dental arch form from 3D mesh model. The feature points are found by the relationship between the vertex of the triangle mesh model and the occlusal plane and the dental arch form is gotten by a two-step curve fitting method. The first curve fitting is in result of an approximate dental arch form which used as an additional reference to search the accurate feature points, the exact dental arch is gotten by the second curve fitting.Secondly, an interactive segmentation algorithm on dental models is proposed, which can accurately separate single tooth from dental model. The bio-information which represented by the discrete curvature of the 3-Ddental model is computed, using the computed discrete curvature as the reference, and then the feature regions in which the segmentation boundary may be included is filtered out according given curvature threshold. The feature regions including segmentation boundary are"bridged"interactively. The skeleton line of the feature region is extracted according to the bio-information of the 3d dental model. The segmentation boundary is got after branches removing and smoothing operations of the skeleton line. Finally, the teeth of the dental model are separated one by one along the segmentation boundary.Thirdly, based on the properties of the physical deformation, a simplified mass-spring model is established to simulate the deformation of gum which caused by the movement of tooth. Then its dynamics characteristic is analyzed, finally, numerical solution of the Lagrange equation is presented.