Two-tone agent which visibly reveals the presence of early and mature biofilm with the intention of eliminating it all, even in difficult-to-access areas. The reddish colour shows new biofilm and the blue colour shows mature biofilm. Colour removal means biofilm removal, including on soft tissues. Highlight the disclosed biofilm and problematic areas to patients, motivating them to practise better oral care at home. Once biofilm is removed, calculus is easier to detect.