Development of system measuring and analysing teeth crown form using light cutting method for dental CAD/CAM technology

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The purpose of this study is mesurment and analisys tooth crown form and dental arch using digital CCD camera and light cutting method. Moreover we considered measuring the shape of tooth crown form in the mouth directly. At first, we made a special stage with 6 degrees of freedom. Then we examined the methods of measurments using slit light, cross-pattern, and maluti-value pattern, et al. From the result, we decided to use multi slit pattern. This pattern was constituted alternately white line (2 pixels width) and black line (32 pixels width). The image provided using CCD camera was handled by the dynamic threshold value, and it was converted into black and white image, and 3 dimensional value was calculated. Then, we considerd the problems of crook or dim of image coming from focusing in optics system, and concluded that it is easy to measure rough shape, but not enough to do a minute measurement for abutment tooth. If the shape of tooth is mesured directly in the mouth using this method, it is important to make up this system into small size that is possible to insert in a mouth. We think it need the new technology break through the problems.