Influência de diferentes protocolos de polimento na rugosidade e adesão bacteriana em cerâmicas de dissilicato de lítio e silicato de lítio reforçadas com zircônia

Abstract

Ceramic restorations require adjustments before or after cementation. To restore surface smoothness, reglazing or manual polishing is necessary; however, there is controversy regarding the best method. Therefore, the aim of this study was to compare surface roughness and bacterial adhesion on lithium disilicate and zirconiareinforced lithium silicate ceramics after different polishing protocols. Seventy-two rectangular samples were fabricated for each ceramic group: Lithium disilicate (LD), zirconia-reinforced lithium silicate - Vita Suprinity (VS), zirconia-reinforced lithium silicate - Celtra Duo with firing (CD-AF), and zirconia-reinforced lithium silicate - Celtra Duo without firing (CD). The samples were divided into six randomized groups according to the protocol: Glaze (GL), Exacerapol (EX), Ceramisté (CR), Pk 5.1 Ceram (PK), Optragloss (OP), and Control (CO). Manual polishing protocols were performed using abrasive rubber points with the same shape, in two- or three-step processes, from different commercial brands. Roughness was assessed before and after each protocol. Two representative samples from each group were evaluated using scanning electron microscopy. Biofilm adhesion of Streptococcus mutans was determined by colony-forming units per milliliter (CFU/ml). Statistical analysis was performed using Jamovi software, employing two-way ANOVA followed by Bonferroni post hoc test to identify significant differences between groups. A Pearson correlation test was also conducted to evaluate the correlation between bacterial adhesion and roughness in each ceramic group. The significance level was set at P = 0.05. A significant interaction between ceramics and protocols was observed in terms of roughness change (F(12,220) = 19.7, P < 0.006, η²partial = 0.517) and bacterial adhesion (F(3,216) = 0.234, P < 0.872, η²partial = 0.003). The LD ceramic showed the least roughness alteration, while CD had the highest. When evaluating only protocols, there were significant differences between manual polishing protocols and glaze. A large positive correlation was found between adhesion and roughness in all groups: LD (r = 0.589, P < 0.001), VS (r = 0.6, P < 0.001), CD (r = 0.649, P < 0.001), and CD-AF (r = 0.727, P < 0.001). For LD and VS, the most effective protocol was OP, while for CD-AF and CD, it was PK. All ceramics showed less roughness alteration with EX and CR protocols. For bacterial adhesion, significant differences were only observed between ceramics under the GL protocol. Regarding roughness alteration, all protocols except GL generated significant differences between ceramics. The SEM analysis confirmed the roughness results. It was concluded that all ceramics showed decreased roughness and bacterial adhesion after the different polishing protocols but exhibited distinct behaviors when subjected to the same polishing protocol.