This study evaluated the effect of two-step polishing procedures on the surface roughness of bulk fill restorative materials. Disk-shaped specimens (10 × 1.5 mm) were prepared from four resin composites: Filtek One Bulk Fill (3M ESPE) and Tetric PowerFill (Ivoclar Vivadent), both bulk fill nanohybrid composites; X-tra fil LC (Voco), a bulk fill microfilled composite; and Filtek Supreme (3M ESPE), a conventional nanofilled composite used as a control. Polishing was performed using D-Fine Double Diamond, Sof-Lex Diamond, and A.S.A.P. polishers. Each system was applied for 30 s with a slow-speed handpiece at 10,000 rpm under water cooling. Surface roughness (Ra) was measured before and after polishing using a profilometer, with three readings per specimen, and surface morphology was assessed by scanning electron microscopy. Data were analyzed using two-way ANOVA and Tukey’s HSD test (α = 0.05). Significant differences were observed for the interaction between composite type and polishing system (p < 0.001). The lowest Ra value was obtained for Filtek One polished with Sof-Lex Diamond, while the highest surface roughness was observed for X-tra fil LC polished with D-Fine (0.800 ± 0.072 μm). SEM analysis indicated that composites containing larger filler particles exhibited greater surface roughness. In conclusion, surface roughness after polishing was primarily material dependent, with nanofilled composites demonstrating superior polishability compared to materials with larger filler particles.
Chagas et al. (Sat,) studied this question.