OVERSATURATION OF SALIVA WITH HYDROXYAPATITE

¹ Max Planck Institut für Biochemie, Tübingen, Germany

Unstimulated and stimulated saliva of persons resistant to dental caries was brought into contact with pure hydroxyapatite in vitro. The concentrations of calcium and phosphate were decreased in both kinds of saliva. However, in samples of stimulated saliva the decrease was greater than in that of unstimulated saliva. This phenomenon was shown to be due to the fact that both kinds of saliva represent oversaturated solutions, in which hydroxyapatite is crystallized by the addition of hydroxyapatite crystals. Unstimulated saliva is less oversaturated than stimulated saliva due to its higher dissolving capacity. This in return is induced by the lower pH and higher buffering capacity of unstimulated saliva.

The in vivo-analogy of a process of oversaturation of saliva with hydroxyapatite would point to a possible mechanism of remineralization of the enamel but requires in vivo demonstration.