Inhibition of dental erosion by casein and casein-derived proteins

The application of milk-derived proteins such as casein as anti-erosion agents in oral healthcare products is of current interest. The aim of this study was to investigate the potential of 3 commercially available, milk-derived proteins as agents to inhibit enamel erosion. Aqueous solutions of 0.5% w/v casein, casein phosphopeptide (CPP) or glycomacropeptide (GMP) with and without 300 ppm fluoride (F, as NaF) were investigated with regard to enamel softening and tissue loss, in comparison with a deionised water (DIW) negative control and 300 ppm F positive control. Casein and F reduced enamel surface softening compared to DIW, but CPP and GMP did not (DIW: 58.2% reduction in hardness; F: 13.3%; casein: 21.8%; CPP: 50.8%; GMP: 62.4%). Similar results were obtained with solutions containing protein and F, and the effects were statistically indistinguishable from protein alone (casein + F: 19.1%; CPP + F: 48.2%; GMP + F: 66.1%). By contrast, all protein solutions and F significantly reduced tissue loss (p < 0.050; DIW: 25.8 μm tissue loss; F: 21.6 μm; casein: 20.3 μm; CPP: 20.5 μm; GMP: 20.0 μm). Solutions containing protein and F reduced erosion more than protein alone, but this difference was only significant from protein alone for casein (casein + F: 12.2 μm; CPP + F: 17.3 μm; GMP + F: 18.2 μm). Casein and casein-derived proteins may therefore have the potential to act as agents to reduce or prevent enamel erosion. Furthermore, the erosion-reducing efficacy is not reduced by F, and is in some cases enhanced.