In vitro evaluation of surface roughness and color stability of CAD/CAM ceramics polished with different methods

The aim of this study is to examine the effect of surface finishing procedure applied for couple of new generation CAD-CAM ceramics on the surface roughness and color stability of ceramics while using parameters that can color the surface. In this study, three different CAD-CAM materials were used in A2 shade: Nice (NI), Vita Suprinity (VS) and Cerasmart (CS). A total of 240 samples were prepared, 80 of each ceramic with a thickness of 1,5 mm. The samples were divided according to their surface finishing procedures into two groups of mechanical polishing or glaze. After the surface finishing procedure were applied, they were again divided into 4 subgroups according to the exposure methods; The first group was kept in distilled water and named as the control group (K), the second group was exposed to cigarette smoke (S), brushing with toothpaste (F) was applied to the third group, and brushing with toothpaste (SF) was applied to the fourth group after cigarette smoke exposure. The surface roughness of the samples was measured using a mechanical profilometer. Color measurements were measured with a colorimeter device at the beginning and after surface treatments. The color change ΔE00 was calculated using, L*, a*, b* values. Statistical analyzes were performed with the three-way Anova and Bonferroni test (p<0.05). The mechanical polishing groups of VS and CS ceramics had higher average surface roughness values (Ra) more than the glaze groups (p<0.05). Among the control groups, the highest Ra value was found in the mechanical polishing group of VS ceramic, and the lowest was found in the glaze group of CS ceramic. In the study, all Ra results were found below the critical roughness value. Considering the mean color change (ΔE00*) results, a significant difference was found in color change values between the Control group and S, F, SF surface applications in the NI and CS mechanical polishing and glaze groups (p<0.05). In the VS ceramic Glaze group, no significant difference was found between the C and F surface applications (p>0.05). Since all average surface roughness values are below the critical roughness value, glaze and mechanical polishing can be used as alternatives to each other. The VS glaze group showed more color stability and the acceptable color change values in comparison to all of the used ceramics' glaze and mechanical polishing groups.