Résumé
Objective: To develop a new denture grinding machine to replace the manually grinding procedure for metallic denture parts. Methods: Two hexagonal barrels were symmetrically fixed on a round plate. The direction of rotation and revolution of the barrels were reversed. The denture parts that were put into the barrels together with grinding materials and solution were ground by centrifugal force caused by rotation and revolution of the barrels. Results: The surface roughness of pure titanium castings went down from 1.060 ?m to 0.3113 ?m after ground with the automatic grinding machine using different shapes of grinding materials in series. Conclusion: The automatic grinding machine is competent for grinding the metallic denture parts.
Résumé
Objective: To measure and compare the color of a new and a conventional Vita shade guide(VITAPAN 3D-Master and LUMIN RVACUUM-Farbskala) in order to provide the references for clinical application.Methods: Color in the two shade guides was measured with Minolta colorimeter CR-321 under the light of D 65 and reported in CIE1976L*a*b* color system. Each tab was detected 3 times in the same dimensions at the middle facial surface. Mean values were calculated as the shade of the tab.Results: The range of color value in VITAPAN 3D-Master was larger than that in LUMIN R VACUUM-Farbaskala because the lower value tab was added. The distrbution of a* deviated to the red color , while the green color was relatively deficient. The yellow color could cover the color space of Chinese teeth, and the blue was not enough, although the distribution of b* was enlarged. The tabs of the two shade guides did not match with each other. Only a few tabs could not tell in shade by naked eyes. Conclusion: VITAPAN 3D -Master shade guide can not cover the color of Chinese teeth although it has 10 tabs added and color space enlarged.