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 (12.4×14.5×2mm) and monolithic zirconia (17.5×12.5×2.5mm). 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 4-8, 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 non-contact 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. This article is protected by copyright. All rights reserved.