Effects of milk on enamel solubility.

A reproducible method for comparing the effects of treatment with milk products on the acid solubility of enamel surfaces is described. Using this method it was found that treatment with cows’ milk reduced solubility by more than 20 per cent, regardless of whether it was raw or pasteurized whole or skim milk. Reconstituted whole and reconstituted skim milk gave similar reductions. Similar depressions of solubility followed treatment with cream or whey. Butter gave low and inconsistent reductions. No difference was found in the solubility effects of reconstituted dry skim milk obtained from twenty-three locations in the United States. Tests showed that the protective agent in milk reacts rapidly with the enamel and resists washing. That it is protein in nature is indicated by the finding that the full solubility reduction is given by treatment with casein solutions and mostly removed by washing with a protein solvent.