Development of the training system for the tooth preparation using a personal computer

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Recently CAD/CAM technology has been introduced in a dental field to be expected to reduce the dental laboratory procedure. This technology included not only the technical aspect where wax-up and casting is just replaced to computer assisted technology but also the environmental aspect to eliminate intermediate material such as impression material, stone, wax and investment. In addition, we expected to control the quality of prostheses by aiding computer. Furthermore, we aimed to apply this technology to education especially in the field of tooth preparation. We already developed the original CAD/CAM system to fabricate ceramic crowns automatically on stone models. In this study digitizing accuracy in the develop system was evaluated. The model for the simple standardized abutment was prepared and digitized by a laser digitizer in the CAD/CAM machine. Digitized data was compared with those digitized by three dimensional precision touching probe digitizer (UAA-CAA 850, Karl Zeiss). The … More sectioned surface of the abutment digitized by the laser displacemeter in the machine indicated the data scattering was observed on the diagram that was affected by the secondary reflection and several noise. Maximum scattering was (]SY.+-。[)600mum. Four receptors were composed for one laser beam in the laser digitizer to compare and select the suitable data. However, the result suggested we need to improve ccuracy of digitizing. We developed the modified CAD/CAM machine where the supporting parts for digitizing and machining were different to eliminate useless overhang. Noise during digitizing reduced drastically in the new machine because of the improvement of the light axis of the displacemeter and filter properties and the prevention of random reflection even if only 2 PSD sensors were fixed in the new machine. We also develop the software to express the digitized abutment on the monitor where students could understand the difference between their prepared abutment and the master model. We concluded the developed CAD/CAM device was expecting in the field of education in the future. Less