Independent researches have shown that the Contrast bleaching products are one of the three in Europe who have a good Ph value: 7,9. It has been proven that a Ph value of 7 or higher is better for the enamel. Well know other bleaching systems, which have Ph values of 5.5, 5.8 or 6.1, are to acid so can damage teeth. Call and ask for this test result: an overview of all bleaching systems with their Ph value. +31 (0) 416 671 740.