Another metastable solution has been described in U. In this way, the formation of large insoluble crystals of apatite is prevented and coated small hydroxyapatite crystals of higher water solubility are attained. One or more sources of each calcium ions and phosphate ions may be employed.
As described in Ciba Foundation Symposium, "Hard Tissue Growth Repair and Remineralization (Elsevier)," Associated Scientific Publishers, New York, 1973 in the article by Francis et al, "Chemical Agents in the Control of Calcification Processes in Biological Systems," pages 57-83, particularly at pages 75-78, an antinucleating agent (e.g., a diphosphonate) can in sufficient quantity at a physiological p H completely absorb onto a spherical nucleated particle of hydroxyapatite as it forms and entirely block crystal growth. 4,224,308 as well as an inhibitor of corrosion of aluminum in U. The stability provided by the effective antinucleating agents prevents spontaneous precipitation on enamel surfaces and thereby permits diffusion of the remineralizing components to subsurface lesions.
A preservative such as sodium benzoate or methyl-4-hydroxybenzoate may be employed to reduce bacterial growth.
Typically, about 35,000 ppm of calcium ion and about 40,000 ppm of phosphate can be employed and precipitation still avoided.
In the prior art it has been difficult to maintain the solubility of calcium phosphate particularly in the presence of a fluoride source.
An electrolyte salt as an alkali metal (e.g., sodium or potassium) chloride may be present (e.g., 1 to 1000 ppm) in the stable remineralizing solution to further improve stability and diffusion of remineralizing material into subsurface lesions.
Acidic materials are used to reduce the p H to about 2-4, typically about 2.8-3.8, in order to maintain clarity of the solution.