The effect of polishing pastes on the surface roughness, microhardness, gloss, and color change of resin composites

The use of polishing pastes in the final surface preparation of resin composite restorations has become increasingly common. This study aimed to evaluate the effects of polishing pastes containing abrasives of different particle sizes on the surface roughness, microhardness, gloss, and color change of resin composites. Specimens (10 × 2 mm³) were prepared from nanofill, nanohybrid, and supra-nano resin composites. After finishing and polishing procedures, polishing pastes containing diamond particles of < 1 μm (Lucida, Diashine), 1 μm (DiaPolisher, GC), and 0.5 μm (Diamond Polish Mint, Ultradent) were applied. Baseline measurements of surface roughness, microhardness, gloss, and color were recorded. Following artificial aging (5000 cycles), changes in these parameters were evaluated. Data were analyzed using two-way analysis of variance (ANOVA) and Tukey’s post hoc test (p < 0.05). After the finishing and polishing procedures, no statistically significant decrease in surface roughness was observed in the nanofill and supra-nano resin composites following paste application (p > 0.05), whereas a statistically significant reduction was found in the nanohybrid composite (p < 0.001). No statistically significant difference was detected among the polishing pastes containing abrasives of different particle sizes (p > 0.05). Following the finishing and polishing procedures, specimens treated with polishing pastes exhibited a statistically significant reduction in surface roughness (p < 0.001), whereas no significant differences were observed among the pastes containing abrasives of different particle sizes (p > 0.05). The application of polishing pastes did not affect the surface microhardness of the resin composites. After the finishing and polishing procedures, the use of polishing pastes did not influence the gloss of nanofill and supra-nano resin composites (p > 0.05), but resulted in a statistically significant increase in the gloss of nanohybrid composites (p < 0.001). Resin composites treated with polishing pastes after finishing and polishing exhibited significantly less color change (p < 0.001). While polishing pastes did not influence the microhardness of resin composites, they improved surface roughness, gloss, and color stability. No significant differences were found among the different polishing pastes. The use of polishing pastes following finishing and polishing procedures may positively influence the surface roughness, gloss, and color stability of resin composites, thereby enhancing the clinical success of restorations.