Comparative Study of the Effectiveness of Laboratory‐Formulated Polishing Pastes for Two CAD/CAM Ceramic Restorative Materials

Purpose To evaluate the effect of different polishing pastes with different particle sizes on the surface finish of two different CAD/CAM ceramics. Materials and Methods A total of 128 specimens were prepared of two CAD/CAM ceramics: lithium disilicate (12.4 × 14.5 × 2 mm) and monolithic zirconia (17.5 × 12.5 × 2.5 mm). They were divided randomly into 8 groups according to surface treatment (n = 8). Group 1 (control) was left as received after crystallization or sintering with no further surface treatment; Group 2 (glazed); Group 3 (positive control), where specimens were polished using standardized surface treatment (medium grit silicon carbide discs, rubber cup and pumice slurry, then rubber cup and toothpaste). For groups 4 to 8, in addition to silicon carbide and pumice slurry polishing, specimens were further polished using a diamond paste (DP), and polishing pastes of microzirconia (MZ), nanosilica (NS), nanodiamond (ND), and nanozirconia (NZ), respectively. Surface roughness (Ra) was measured using noncontact profilometer. The mean values were compared using ANOVA and Post Hoc Tukey's test (α = 0.05). Specimens’ surfaces were studied using a scanning electron microscope (SEM). Results Positive control group and MZ exhibited significant Ra of lithium disilicate compared to control (p ˂ 0.001), glazed (p = 0.001), DPs (p = 0.002), NS (p ˂ 0.001), ND (p ˂ 0.001), and NZ (p = 0.002). In the case of zirconia, positive control showed a significantly higher Ra compared to all other groups (p ˂ 0.001). No statistical difference was found between all other polishing techniques (positive control, glazed, DPs, NS, ND, MZ, and NZ) (p > 0.05). Conclusion Polishing with ND, NZ, and NS lab‐formulated pastes produced surfaces with comparable smoothness to control and glazed specimens for lithium disilicate and zirconia ceramic materials.