Abstract: Biomedical materials and, in particular, to substituted calcium phosphate (e.g. apatite and hydroxyapatite) materials for use as synthetic bone.

Abstract: A process for the preparation of a single phase magnesium- and carbonate-substituted hydroxyapatite composition, which process comprises the steps of (i) preparing an aqueous solution containing CO32− and PO43− ions in the substantial absence of cations other than H+ ions; (ii) mixing the solution from step (i) with an aqueous calcium- and magnesium-containing solution or suspension; and (iii) collecting and drying the precipitate formed in step (ii); the ratio of (Ca+Mg/P) in the calcium- and magnesium-containing solution or suspension and the phosphorus-containing solution, when mixed together, being maintained at 1.67, or above. The product of the process is novel and comprises up to 0.5% magnesium and up to 1% of carbonate substituted into the hydroxyapatite structure and which does not contain Na+ or NH4+ ions, the ratio of (Ca+Mg/P) being greater than 1.67.

Abstract: A process for the preparation of a single phase carbonate-substituted hydroxyapatite composition, which process comprises the steps of (i) preparing an aqueous solution containing Co32− and PO43− ions in the substantial absence of cations other than H+ ions: (ii) mixing the solution from step (i) with an aqueous solution or suspension of a calcium compound; and (iii) collecting and drying the precipitate formed in step (ii); the ratio of Ca/P in the calcium-containing solution or suspension and the phosphorus-containing solution, when mixed together, being maintained above 1.67. The product of the process is novel with a Ca/P molar ratio of greater than 1.67 and comprises up to 5% by weight of CO32− ions substituted in the B site or the B and A sites of the hydroxyapatite structure, with at least 50% of the CO32− ions being substituted on the B site. This product does not contain Na+ or NH4+ ions.