Wongpraparatana I, et al. - Experts pursued this study in order to comparatively analyze the effect of simulated bleaching with a 10% carbamide peroxide (CP) or a 40% hydrogen peroxide (HP) system on the roughness of the surface of resin composite and resin-modified glass ionomer cement (RMGI) and streptococcal biofilm formation over the surfaces. An increase was noted in surface roughness and biofilm formation on resin composite and RMGI via simulated bleaching with 10% CP or 40% HP, except for Streptococcus sanguinis biofilm on RMGI.