The effect of polishing systems on surface roughness of nanohybrid and microhybrid resin composites.

PURPOSE: To compare the effect of polishing systems on surface roughness of nanohybrid and microhybrid resin composites. METHODS: Two types of restorative resin composites and two one-step polishing systems were used in this study (IPS Empress Direct as the nanohybrid resin composite and Filtek P90 as the microhybrid). A total of 120 discs were fabricated (n=120). The specimens were divided into six groups of n=20 each. For polishing systems, PoGo One-Step Diamond Micro-Polisher and OptraPol Next Generation were selected. The before and after mean Ra values were recorded using a surface profilometer. Results were statistically analyzed with the Kruskal-Wallis H and the Mann-Whitney U tests. A P-value of </=0.05 was considered statistically significant. RESULTS: PoGo polishing system recorded the lowest surface roughness, in case of both nano and microhybrid composites, with mean Ra values of 0.060 microm and 0.108 microm, respectively. PoGo also produced maximum reduction in the surface roughness in the nanohybrid group with 56.83%. OptraPol recorded a comparatively similar mean Ra value of 0.067 microm for the nanohybrid composites but recorded the least reduction in surface roughness with 48.41% for the microhybrid group. CLINICAL SIGNIFICANCE: One-step diamond polishing systems combined with nanohybrid resin composites exhibit increased surface smoothness compared to microhybrids.