Influence of polishing duration on surface roughness of resin composites

There is a need for effective polishing instruments for resin composite restorations with highly polished surfaces. The purpose of this study was to investigate the influence of polishing duration on surface roughness of light-cured resin composites. Four polishing systems, Compomaster (Shofu), Silicone Points C Type (Shofu), Super Snap (Shofu) and Enhance Finishing and Polishing System (Dentsply/Caulk), were used to polish two commercially available resin composites, Clearfil AP-X (Kuraray Medical) and Lite-Fil II A (Shofu). Resin pastes were condensed into molds (10 mm in diameter, 5 mm in depth) and light irradiated for 40 s. Composite surfaces were ground with # 600 SiC paper followed by polishing with an instrument for 30 s, and the surface roughness was measured every 10 s during polishing procedures. The average surface roughnesses (Ra) were determined using a profilometer. Data were analyzed by Tukey HSD test (P = 0.05). After 30 s of polishing, mean Ra values ranged from 0.07 to 0.50 for Clearfil AP-X, and from 0.11 to 0.57 for Lite-Fil II A. Although the time required for polishing was longer, the surface finish produced by multiple-step polishing systems was superior to that obtained with one-step polishing systems.