Purpose: This study evaluated the surface-roughness of three resin-based restoratives after storage in different media and tooth-brushing. Methods: Fifteen discs were fabricated for each material: Filtek Supreme-Plus, nano-hybrid; KetacN100, nano-ionomer; and Filtek-LS, silorane- based. Discs were divided into three subgroups according to storage media: deionised water (control); lactic acid; and sodium-hydroxide, then stored for one week at 37°C and subjected to power-tooth-brushing abrasion for 100,000strokes (representing 4.2yr clinical use). Ra values were determined by stereo-microscope 40X (Olympus DP10, SZ-PT, Japan) with software: Image J1.4.1 (NIH, USA). Representative ESEM images were also obtained. Results: storage media and tooth brushing abrasion significantly increased surface-roughness of all tested materials. However, there was no significant difference between mean Ra of Filtek-Supreme-Plus and Ketak-Nano which had highest mean Ra compared to Filtek-LS which showed significantly lowest mean Ra values. Conclusions: both the storage media and tooth brushing affected the surface roughness of all tested materials. Silorane-based restorative material exhibited more acid and abrasion resistance than methacrylate-based restorative materials.