OBJECTIVE: To evaluate the effect of polishing systems on the color and roughness of conventional and bulk-fill nanofilled resins, compared to conventional and bulk-fill nano-hybrid resins with S-PRG fillers. MATERIALS AND METHODS: Discs (n = 12) were fabricated from the following resin composites: conventional nanofilled resin (Filtek Z350 XT, 3 M), bulk-fill nanofilled resin (Filtek One Bulk-Fill, 3 M), conventional nano-hybrid resin with S-PRG fillers (Beautifil II LS, Shofu), and bulk-fill nano-hybrid resin with S-PRG filler (Beautifil Bulk Restorative, Shofu). Polishing was conducted using multi-grit aluminum oxide abrasive discs (Sof-Lex Pop On, 3 M) or a single-grit aluminum oxide tip (OneGloss, Shofu). Roughness (Ra) and color (CIEL*a*b*, ΔE RESULTS: Roughness increased after polishing with the aluminum oxide tip for all materials (p <
0.0001
Mann-Whitney). Bulk-fill nanofilled resin showed increased roughness, while conventional nano-hybrid resin with S-PRG filler showed decreased roughness after multi-grit disc polishing (p <
0.0001
Mann-Whitney). Coffee staining significantly increased the roughness in resin composites with S-PRG filler (p <
0.0001
Mann-Whitney). All resin composites exhibited reduced L* and b* (p <
0.05
generalized linear mixed models for repeated measures) and increased a* (p <
0.05
Friedman and Nemenyi) values after coffee staining. ΔE CONCLUSION: Polishing systems significantly influence resin composite roughness based on their composition, with single-grit polishing causing the highest roughness. Bulk-fill nano-hybrid resin composite with S-PRG filler exhibited the greatest color and roughness changes post-staining. CLINICAL RELEVANCE: Bulk-fill resin composite with S-PRG filler demonstrated lower color and surface stability. Importantly, these changes were significantly mitigated when polished using a multi-stage polishing system.