Evidence for intermediate metastable states during equilibration of bone and dental tissues

Experimental data were collected on the solubility equilibrium of the mineral of bone, tooth enamel and calcium phosphate renal stones. Evaluation in the form of potential diagrams of Ca(OH)2 versus H3PO4 shows that Ca/P ratios of 1, 4/3, 10/7, 3/2 and 5/3, related to phases like brushite, octocalcium phosphate, whitlockite, defective apatite and hydroxyapatite respectively can be important. These facts allow the interpretation that many of these calcium phosphates are present simultaneously in biominerals or that they are formed during the equilibration.