A novel technique has been applied to manufacture porous hydroxyapatite for implant applications. The process involved generation of foam from an aqueous suspension of the powder followed by in situ polymerisation of organic monomers, which had been previously added to the compositions. This method produces strong gelled and complex-shaped bodies with up to 90% porosity that can withstand machining in the green state. The organic additives are eliminated at temperatures above 300 °C and sintering is carried out for consolidation of the ceramic matrix. An optimized mechanical strength results from a highly densified matrix combined with spherical inter-connected cells of diameter ranging from 20 to 1000 <FONT FACE="Symbol">m</font>m and channels of 10-100 <FONT FACE="Symbol">m</font>m, depending on the specimen density. Cytotoxicity test was conducted with sintered HA extracts in contact with mammalian cells, based on a quantitative method of colonies formation suppression. The in vitro test revealed that the original purity of the biomedical-grade hydroxyapatite powder was neither affected through processing nor by the employed reagents.
Hydroxyapatite; gelcating; processsing; porous ceramics
