RESUMEN
OBJECTIVES: To evaluate the surface roughness and gloss of three nanohybrid resin composites after polishing with three different polishing systems. MATERIALS AND METHODS: A total number of 112 disc specimens (10 × 3 mm) were prepared from nanohybrid-Empress Direct (ID), Grandio (GR), Filtek Z350 (Z350) and a microhybrid resin composite restorative materials-Filtek Z250 (Z250). Following 24-hour storage in 37°C distilled water, each composite group (n = 28) was assigned into four groups (n = 7) according to finishing/polishing (F/P) system: Mylar strip, Optrapol, Politip, and Sof-Lex (SL). The surface roughness (Ra, mm) was measured by a novel three-dimensional method using an image analysis software attached to an environmental scanning electron microscope. A glossometer was used to measure the surface gloss. RESULTS: Statistical analysis used was ANOVA test. Two-way Anova test revealed that the "type of composite" and "F/P techniques" had a significant effect on both surface roughness and gloss of the tested resin composite materials (p < 0.05). Tukey's post hoc test showed that ID, GR, and Z350 revealed lower surface roughness and higher surface gloss than Z250 within the same polishing system (p < 0.05). Sof-Lex polishing discs produced the lowest surface roughness and highest surface gloss values compared with Optrapol and Politip (p < 0.05). CONCLUSION: The tested F/P systems provided comparable surface roughness and gloss for nanohybrid composites. The Sof-Lex system provided the best surface roughness and gloss for nanohybrid composites.