Effect of various polishing systems on the surface roughness and Streptococcus mutans adhesion of CAD/CAM ceramic materials

BACKGROUND: CAD/CAM ceramics provide superior predictability; however, minor adjustments are often required prior to cementation to achieve adequate interdental and occlusal contacts and to improve overall contours. These adjustments increase the surface roughness of ceramic restorations, which can promote bacterial adhesion. Therefore, this study evaluated the effects of three polishing systems (Komet, OptraGloss, EVE) on surface roughness and Streptococcus mutans adhesion to lithium disilicate and translucent zirconia ceramics. METHODS: ) and topography were assessed using a contact profilometer and scanning electron microscopy (SEM). S. mutans adhesion biofilm area coverage (48-hour biofilm) was assessed as CLSM-derived area coverage (%) using confocal laser scanning microscopy (CLSM). Data were statistically analyzed using Welch's ANOVA, the Games-Howell post hoc test, and the Kruskal-Wallis test. RESULTS: Compared with the other groups, the glazed groups presented significantly lower surface roughness (Ra: 0.03 μm for lithium disilicate and 0.02 μm for zirconia) and CLSM-derived biofilm area coverage (median: 0.14% for lithium disilicate and 0.15% for zirconia) (P < 0.001). Among the polished groups, the three polishing systems demonstrated significant differences in surface roughness values (Ra: 0.44-0.86 μm for lithium disilicate and 0.39-0.68 μm for zirconia; P < 0.001); however, no significant differences in S. mutans adhesion were observed (P = 1.000 for lithium disilicate; P ≥ 0.903 for zirconia). CONCLUSIONS: Although all three polishing systems effectively reduced surface roughness after grinding, none achieved the smoothness or the level of biofilm area coverage reduction of the initial glazed surfaces.