Research Of Digital Design Technologies For Dental Prosthetic Bridge

In recent years,digital design and manufacturing technology have been promoting oral repair treatment to the more precise,simple and efficient direction.Fixed bridge is one of the most common prosthesis in prosthodontics,it is used to repair the shape and function.In this paper,3D surface modeling design of fixed bridge prosthesis is taken as the research object,the key technologies in the process of fixed bridge digital design: the surface structure of pontic,the surface structure of connector,and the collison detection is studied,are presented to achieve a more complete prosthesis modeling design system.Main contents and achievements are as follows:(1)The pontic surface structure technology is studied.In order to restore the shape and function of the missing tooth,the upper surface of the pontic is generated by cutting the standard crown.Because the standard crown has no gingival surface,it is necessary to design the gingival surface of the pontic.In order to avoid the self-intersection problem caused by the traditional offset method,an algorithm based on the implicit surface offset to generate the gingival surface is proposed.There is a gap between the upper surface and gingival surface,and a transitional surface needs to be designed.Finally,the upper surface,the gingival surface of the pontic and the transitional surface are sutured into a whole by the mesh fusion algorithm.(2)Connector surface structure technology is studied.Traditional design method is to store connector model in system database,it is called and make boolean operations to form a full crown bridge,but the editing ability is poor and the efficiency is low.In order to solve the problems,an algorithm based on cross-section template projection to generate a connector is proposed.The curves at both ends of the connector are obtained through projection.The connector is generated between the curves using a skinning algorithm,and then merged with the retainer and pontic through the cutting and stitching algorithm.Connector generated has a strong editing capabilities.The area of the middle section of the connector can be detected in the editing process,to ensure that the design of the connector has enough strength.(3)After the design of the denture bridge is completed,verification of the occlusal surface needs to be performed by virtual occlusion,so that multiple contact points are formed between the bridge body and the jaw teeth,which increases the efficiency of chewing and the comfort of wearing by the patient.In order to meet the real-time requirements of interference detection in virtual bite adjustment process,a collision detection algorithm based on hybrid bounding box is propos ed to solve the collision area of the model.Based on the collision detection results,the calculation method of the piercing depth of the model is also studied.Depth values are displayed by means of a histogram,providing an intuitive basis for adjustmen ts in the dental restoration design process.(4)On the basis of the above research,a CAD software is developed based on Open GL graphics library and Open Mesh library.And a complete example of fixed bridge prosthesis design is displayed.