الفهرس 
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Abstract
Objectives: This study was designed to investigate the effect of filler size and polishing systems on the surface roughness and gloss of four resin composite restorative materials Materials and Methods: A total number of 112 resin composite specimens were fabricated (10×2 mm) according to the resin composite materials used ; nanohybrid [Empress Direct, Ivoclar Vivadent (ID), Grandio, Voco (GR) and Filtec Z550, 3M ESPE (Z550)] and microhybrid composite [Filtec Z250, 3M ESPE (Z250)] (28 per each material group). Each group was further divided into four subgroups according to the finishing/polishing systems used; Group1: the specimens were kept without finishing/polishing after removal of Mylar strip to act as control group, Group2: the specimens were finished and polished with one-step Optrapol lens, Group3: the specimens were finished with two-step Politip, Group4: The specimens were finished and polished with three-step Sof-Lex aluminum oxide disc system. The average surface roughness (Ra) was measured by Environmental Scanning Electron Microscope (ESEM) while the surface gloss was measured by glossometer. Statistical analysis was done by two-way ANOVA (p = 0.05) with an adjustment for multiple comparisons.Results: The results of two-way ANOVA test revealed that ‘type of composite’ and ‘finishing/polishing techniques’ significantly affect the surface roughness values (p > 0.05).The interaction of both variables was also significant (p >0 .05). Within the same polishing system, ID, GR and Z550 revealed the lower surface roughness and higher surface gloss than Z250. The multi-step Sof-Lex polishing discs produced the lowest surface roughness and highest surface gloss values compared to one-step optrapol and two-step politip (p < 0.05). Optrapol exhibited the highest surface roughness and the lowest surface gloss compared with the remaining test groups.Conclusions:It was concluded that the polishing procedure and the type of composite have significant impacts on surface roughness and gloss of resin composites. The nanohybrid composites showed the best results in surface roughness and gloss when finished with Sof-Lex polishing discs. A positive correlation between the surface roughness and surface gloss was found.