We tried to duplicate the shape of occlusal surface of artificial tooth using the CAD/CAM technique and to replace the occlusal surface of the plastic tooth of denture with gold alloy.
The present CAD/CAM system was composed of the three-dimensional shape measurement system (XYZAX PA 400 A, Tokyo Seimitsu Co. Ltd.), the personal computer (PC 98, NEC), and the computer aided engraving machine (CAMM-2, Roland D. G.).
The contour of occlusal surface of the molar artificial tooth was measured by stepping at 0.5mm intervals. Measured points were interpolated with the spline function to obtain as smooth a surface as possible. Those data were used to cut a methacrylic plate to a pattern of occlusal surface (acrylic pattern). To examine the accuracy of duplication, the space between the acrylic pattern and the plaster core of the artificial tooth was evaluated. The space was represented as the thickness of silicone rubber and measured by using the optical magnifier (Profile projector V-12, Nikon). The thickness ranged from 70μm to 290μm. It was suggested that a CAD/CAM system like the present one is useful to duplicate the occlusal surface of an artificial tooth.
More accurate duplication requires some improvements in the intervals of measuring the contour and cutting the acrylic plate.