Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 18 0 2021 10 23 The Effect of Chemical and Mechanical Degradation on Surface Roughness, Topography, Gloss, and Polish Retention of Three Composites Polished with Five Polishing Systems 3871 3871 Fatemeh Farzaneh Department of Operative Dentistry, School of Dentistry, Shahed University, Tehran, Iran Mahshid Mohammadi-bassir Department of Operative Dentistry, School of Dentistry, Shahed University, Tehran, Iran Mohammad Bagher Rezvani Department of Operative Dentistry, School of Dentistry, Shahed University, Tehran, Iran Fahimeh Dehestani Ardakani Operative Dentistry Resident, Department of Operative Dentistry, School of Dentistry, Shahed University, Tehran, Iran 2020 11 30 2021 04 24 Objective: Finishing and polishing (F/P) of composites is a fundamental step influencing the clinical service of restorations. The aim of this study was to evaluate the effect of different F/P systems on surface roughness, gloss, and polish retention of composite resins. Materials and Methods: One-hundred and five disc-shaped specimens (4×4 mm) were made from nanofilled, microhybrid, and microfilled composites (n=35). The specimens were divided into five subgroups (n=7) for F/P with Sof-Lex (4-step), Shofu (4-step), Cosmedent (3-step), Diacomp Composite-Pro (2-step), and Opti1Step systems. The surface roughness values (Ra and Rz) were measured before and after pH-cycling and simulated toothbrushing. Surface topography was assessed by using a scanning electron microscope (SEM) at three magnifications. For assessment of surface gloss, 45 rectangular specimens (10×8×2 mm) were fabricated from three composites (n=15) and randomly allocated to five subgroups (n=3). Surface gloss was measured before and after aging. The mean values were calculated and analyzed by two-way ANOVA, Tukey, and t-test. Level of significance was set at 0.05.  Results:  The composite type had no significant effect on surface roughness (P>0.05); however, the type of F/P system significantly affected it (P<0.05). The pH-cycling and simulated toothbrushing had no significant effect on gloss or polish retention of the three composites (P>0.05). Conclusion: Type of F/P system had a greater effect on surface roughness and gloss of composite resins than the type of composite. https://fid.tums.ac.ir/index.php/fid/article/view/3871