A Study of Three-Dimensional Accuracy in Dental Prosthesis

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Even though it is projected that the dental prosthesis will soon be manufactured with CAD/CAM technology, the three-dimensional accuracy of dental prosthesis construction using this technology is not known. I requested each of 5 dental technicians to produce 3 model teeth under each of the following three conditions : the original tooth measurement by visual inspection ; the original tooth measurement with calipers ; and in the absence of the original tooth, tooth measurement by extrapolation from the existing opposite and adjacent teeth. The reproduced teeth were measured with a laser displacement meter, and the results compared with the orginal tooth.It was found that the reproduced teeth constructed based on the visual inspection had error of distance of about 500mum. The error of distance was not reduced when the measurement was made using calipers. In general, reproduced teeth made by the dental technicians were deformed. When the technicians attempted to reconstructar eliminated tooth, the error of reproduction increased to about 1000mum.