Manufacture of hydroxyapatite beads for medical applications

Dense, microporous and macroporous hydroxyapatite spherical granules for medical applications were prepared by a new manufacturing procedure. This process is related to a lost wax method and yields beads with a fully controlled porosity, in terms of shape and pore size. A CaCO3 scaffold exhibiting controlled size spherical cavities is impregnated with an aqueous hydroxyapatite suspension. After drying in a plaster mould, a thermal treatment destroys the carbonate scaffold and makes it possible to release the HA beads. By this process, HA beads with diameters in the range of 300 mu m to 3 mm are obtained. A post-thermal treatment of the beads allows the ceramic to be densified at various densification levels. Porous ceramics make it possible to functionalise the hydroxyapatite granules by loading the structure with biologically active substances. Drug releasing kinetics in continuous distilled water flow were analysed as a function of time and ceramic porosity. Spheres continue to release the biological molecules for more than 5 days. (c) 2008 Elsevier Ltd. All rights reserved.