Effect of polishing on color and surface roughness of porcelains

Objectives: Porcelain surface is generally finished by glazing procedure but sometimes it can be removed after cementation because of the occlusal adjustment, correction of contours. The aim of this study was to investigate the effects of different polishing techniques on color change (ΔE) and surface roughness (Ra) of 2 different porcelains. Methods: Firstly 80 porcelain specimens were divided into two subgroups (Ceramco 3 and IPS empress II) then each subgroup was divided into 4 groups (n=10). One group served as a control and had no surface treatment, the glaze layer of each specimen was removed in the other 3 groups and the surfaces were polished with 3 different ceramic polishers (2 different diamond ceramic polishers and 1 occlusal brush set). VITA Easyshade was used to measure color differences in the specimens according to the CIE L*a*b* color system. Surface roughness (Ra) of the porcelain discs were evaluated using a profilometer. One specimen from each group were analyzed with SEM after measurements. The color change (ΔE) and surface roughness (Ra) of porcelains were statistically analyzed by Two-way ANOVA followed by a Tukey HSD test (α=05). Results: There were relationship between the porcelain systems and polishing techniques but no significant differences between porcelain systems for surface Ra values (p>0,05). There was relationship between the porcelain systems and polishing techniques but no significant differences between porcelain systems for ΔE values (p>0,05). The different polishing techniques affected color differences significantly (p<0,01). Conclusion: Polishing procedures were not able to provide a porcelain surface as smooth as the glazed surface for the IPS empress and Ceramco 3 porcelains. Rubber polishing systems are more successful than brushes for polishing porcelains.