Fig. 2From: Effect of roughness and acidic medium on wear behavior of dental resin compositeThe COF curves for the resin composite with different Ra in distilled water and citric acid: a 1.60 ± 0.23 μm; b 0.61 ± 0.04 μm; c 0.19 ± 0.03 μm. d Average COF as a function of Ra in distilled water and citric acid. The regression lines represent the best fit to the experimental dataBack to article page