Comparative fixation of calcium and strontium by synthetic hydroxyapatite.

Strontium can be deposited in bone apatite either by the replacement of surface adsorbed calcium, or by substitution for intracrystalline calcium (1-3). It has also been reported that both of these processes favor the deposition of calcium to that of strontium (3). This report is concerned with the comparative incorporation of calcium and strontium in synthetic apatites. We shall present evidence which indicates that during the crystallization of apatite, the composition of the solid in relation to that of the solution approaches an equilibrium value dependent upon the rate of crystal growth.