Effect of Pyrophosphate on Dissolution of Hydroxyapatite and Its Possible Importance in Calcium Homeostasis.

Hydroxyapatite in equilibrium with physiological concentrations of pyrophos-phate showed a markedly reduced solubility during dissolution experiments in vitro. Since bone contains pyrophosphate, it is suggested that this phenomenon might be important in calcium homeostasis. It is possible that it is also involved in causation and prevention of caries.