Hydroxyapatite compacts were fabricated by pressureless- and hot-pressing of natural powders recycled from pig bones and their sintered property and biostability investigated. Organics of bone were removed by soaking the bones in a NaOH solution. An organic-free hydroxyapatite powder was obtained by calcination of dried bones and milling by an attritor. Porous hydroxyapatite compacts were fabricated by pressureless-sintering which was carried out at a temperature of 1100 ο C for 1 h in a humid atmosphere. Dense hydroxyapatite compacts were prepared by hot-pressing at 1000 ο C for 0.5 h under a pressure of 30 MPa in an Ar atmosphere. Almost the detectable peaks in the calcined powder were identical to hydroxyapatite with a small peak of MgO. Sintered hydroxyapatite compacts have a density of 77% by pressureless-sintering and 95% by hotpressing. An immersion test in buffered water revealed that there was no clear evidence of dissolution for the hot-pressed hydroxyapatite compacts derived from recycled pig bones. By comparison with an extensive dissolution on the surface of an artificial hydroxyapatite compact in buffered water, the hydroxyapatite compacts recycled from pig bones have a superior biostability for in vitro tests

Keywords: Hydroxyapatite, Bioceramics, Pig bone, Recycling