Research On Tooth Modeling And Processing Technology Based On The Cone Beam CT

Dentistry tooth defect is a common and frequently disease,and occurred in the natural persons with the rate of approximately 24%to 53%.The usual treatment is the use of fixed prosthesis repair.The production of conventional dentures used to go through more than 20 programs,just like the preparing an impression,trimming model,carving wax-mould,casting,sandblasting,heaping porcelain,baking porcelain,trimming,grinding,polishing,etc.Although the technology is less demanding,there are several disadvantage with complex process,poor speed,long period and the impact of human.A new generation of oral CT machine obtained CT images in the form of cone beam.It's useful in improving the accuracy of scanning,enhancing the estimate efficiency of diagnosis,and helping doctor to optimize the scheme.It caused the emergence of the field of innovation for dental restorations.Doctor had no use for traditional technology to design fixed prosthesis repair to meet the requirement of patient.They can make craft dentures in combined with CAM technology.Using this technology,general practitioners can create more personalized dentures in according to the actual situation without complex process.There is another advantage with decreasing costing and simplify working procedure.This thesis discussed the technology of CAM and three-dimensional reconstruction of the teeth on the basis of cone beam.(1)Three-dimensional reconstruction of the teeth:We used cone beam to scan teeth on the destination of getting CT image to generate STL file.Then dealt with point cloud data primarily by using the method of Gaussian filtering and threshold segmentation.After that transformed point cloud data into NURBS curve by means of reverse engineering technology and analyzed the strength of teeth by ANSYS software.Finally optimal adjustment can be used to generate the final machining of the dental model and provide the basis for the subsequent NC.(2)the study of multi-axis machining technology in teeth:Because the teeth's structure is small and complex,we used multi-axis machining way to produce denture.This thesis deduced Multi-axis machining linkage algorithm by the way of coordinate transformation and used circumcision method to cut teeth.This picture optimize tool path by the way of optimization techniques between ring and designed arithmetic in accord to this technology.Finally,checked the feasibility of path planning and optimization algorithm by the comparison of different test.(3)Process dental solid models with CAM and simulation:Used CAM four-axis and five-axis to machine dental model and generate the tool path and make four-axis and five-axis post processor.Then draw four-axis and five-axis milling machine and define the movement of components in VERICUT.After that used VERICUT to simulate machining process and evaluate the results.Finally finished the processing of material object and discussed the feature and advantages/disadvantages of STL processing.