This application relates to novel aqueous oral care compositions useful for combining and delivering incompatible stannous fluoride or stannous chloride and potassium salts in a high-water composition, for example, to provide effective caries prevention, protection against dental erosion, and relief from dental hypersensitivity. The compositions comprise stannous fluoride or stannous chloride, nitric acid or a water-soluble nitrate salt, a water-soluble alkali metal polyphosphate and more than 10% water, by weight of the composition.