Efficacy of two polishing systems on the return of surface smoothness of glass-ceramic restorations in posterior teeth. Clinical, randomized, prospective and blinded study

The aim of the study was to verify the lithium disilicate repolishing in the mouth by varying the use of two polishing systems in posterior restorations. Additionally, the behavior of ceramic restorations was longitudinally evaluated according to the modified USPHS criteria. The study included 12 patients who needed at least 2 bilateral posterior teeth to be restored with ceramic in monolithic lithium disilicate, totaling 62 restorations analyzed. The restorations were allocated into two groups: G1 - 31 ceramic restorations using the Exa-Cerapol polishing system, felt and diamond paste, and G2: identical to G1 using the Shofu polishing system, felt and diamond paste. The choice of restorations in each group was randomized according to the split-mouth design concept. The service was performed by graduated professionals, calibrated in the technique, but not aware of the reasons for the study. The restorations were replicated with epoxy resin in 3 moments: after cementation (T0); after occlusal adjustment (T1); and after polishing (T2), for quantitative roughness analysis. Representative samples from each group at the same times were taken for analysis by confocal laser microscope (LSCM). The behavior of ceramic restorations was evaluated longitudinally at the times (T): T0 - after polishing, T1 -30 days after, T2 -180 days after. There was no statistically significant difference between the groups for the tested times (p> 0.05). Statistically significant differences were observed between groups T0 and T1 and between T1 and T2 (p <0.05) in both G1 and G2. The survival rate of restorations without fractures was 100%; survival due to the occurrence of biological complications with restoration replacement (n = 1) was 98.4%; Release rate without restoration replacement (n = 6) was 96.9%. It was concluded that both systems were effective in intraabucal repolishing of monolithic lithium disilicate restorations. The clinical protocol performed by the graduated professionals proved to be effective with no cracks / fractures within 6 months of follow-up.