Influence of Different Polishing Systems on Surface Roughness and Microhardness of Bulk-fill Resin-based Composites: An In Vitro Study

Purpose: To evaluate the surface roughness (Ra) and microhardness of bulk-fill resin-based composites (RBCs) treated with different polishing and finishing systems. Materials and methods: One hundred twenty-eight disks were fabricated with four types of bulk-filled RBCs (<i>n</i> = 32 each) (SDR Plus flowable, SonicFill nanohybrid, Filtek One nanofiller, and Beautifil-Bulk packable). Each group of 32 disks was further divided into subgroups of 8 disks, corresponding to each polishing and finishing system (Enhance^® PoGo^®, HiLusterPLUS, Sof-Lex™, and Super-Snap X-TREME). The Ra was assessed with a surface profilometer. Microhardness was determined using the Vickers hardness test. The surface texture was observed using field-emission scanning electron microscopy. The differences in mean Ra values and microhardness among the groups were determined using analysis of variance (ANOVA). The Tukey test was applied for <i>post hoc</i> comparisons. Correlations between microhardness and bulk-fill RBCs/finishing and polishing protocols were indicated by Pearson’s correlation test. Results: The polishing systems had a significant impact on Ra (<i>p</i> < 0.001). Among the tested combinations, SonicFill 3 RBCs polished with the Super-Snap X-TREME system demonstrated the lowest Ra (0.13 ± 0.13 µm), while SDR Plus polished with the same system exhibited the highest Ra value (0.37 ± 0.10 µm). Microhardness values differed significantly among the RBC types (<i>p</i> < 0.001) but were not significantly influenced by the polishing systems (<i>p</i> > 0.05). A weak yet significant correlation was identified between Ra and microhardness (<i>r</i> = 0.272, <i>p</i> = 0.007). Conclusion: All polishing systems evaluated in this study yielded clinically acceptable Ra values for all tested RBC materials. The smoothest surfaces were achieved with nanohybrid composites polished using the Super-Snap X-TREME system. The roughest surfaces were observed with bulk-fill flowable composites polished with the same system. Despite not being specifically tailored to the tested RBCs, the polishing and finishing systems demonstrated comparable performance in achieving satisfactory Ra. How to cite this article: Omar SH, Alauddin MS, Hassan LA, <i>et al.</i> Influence of Different Polishing Systems on Surface Roughness and Microhardness of Bulk-fill Resin-based Composites: An <i>In Vitro</i> Study. Int J Prosthodont Restor Dent 2024;14(4):242–249.