Preparation of granulated materials on the hydroxylapatite base

In various areas of implantology granulated hydroxylapatite (HA) is used successfully for restoration of different bone defects in the human skeleton. In the present work when speaking about granulated HA the authors mean pure stoichiometrical HA, in which phase and chemical composition correspond to the USA standard. For control purposes the authors used X-ray diffraction analysis and infra-red spectroscopy. The techniques used by the authors for granulation exclude a possibility of preparing amorphous materials. Therefore in all cases granules represent polycrystalline bodies. In terms of sizes of granules there are 4 groups of materials in the authors´ experience: 1) The micron size particles (1-50 microns) or powder, in which dispersion can be adjusted by synthesis conditions (the problem of the preparation of these materials is considered separately). 2) Particles with a size of 0.25-0.5 mm. 3) Particles with a size of 0.5-1.0 mm. 4) Particles with a size of 1.0-2.0 mm. The present work is devoted to manufacturing the last 3 groups of granules. The preparation of these materials is possible by many methods, including rolling, pressing, extrusion and crushing HA ceramic blocks with subsequent fractionation. The authors successfully applied two technologies to make granulated HA: 1) Milling of sintered compact HA with subsequent sieving on fractionation. 2) Rolling in a plate-type teflon granulator