Surface characteristics and bacterial adhesion on single-shade composite resins: A comparative <i>in vitro</i> study of one-step versus multi-step polishing techniques

This study evaluated the effects of two polishing systems, OptraGloss (G; one-step) and OptiDisc (D; multi-step), on surface roughness (SR), contact angle (CA), surface free energy (SFE), and bacterial adhesion on three single-shade composite resins: Omnichroma (O), ZenChroma (Z), and Charisma Diamond One (C). Data for SR, CA, SFE, and adhesion of Streptococcus mutans (S. mutans) and Streptococcus mitis (S. mitis) were analyzed using one-way ANOVA, Tukey post-hoc tests, and Pearson correlation (α=0.05). Multi-step polishing groups (OD, ZD, and CD) exhibited significantly lower SR (0.18, 0.18, and 0.29 µm, respectively) compared to OG (0.46 µm), ZG (0.30 µm), and CG (0.44 µm) (p<0.05). The highest CA was observed in ZG (91.6º). S. mitis adhesion was greater than S. mutans in all groups except OG. A significant correlation was observed between SR and the adhesion of S. mutans (r=0.693, p<0.001). Polishing systems applied to single-shade composite resins did not impact the SFE but affected SR, and bacterial adhesion.