Preparation of Porous Hydroxyapatite/α-Tricalcium Phosphate Composites by a Colloidal Process

Abstract

Porous hydroxyapatite (HAp)/α-tricalcium phosphate (α-TCP) composites were prepared by a colloidal process. HAp/α-TCP mixed powder was ultrasonically dispersed in an aqueous solution containing an optimum amount of polycarboxylic acid ammonium as polymer dispersant. After the colloidal process, polymethyl methacrylate (PMMA) was added to the slurries, followed by dehydration. A pressure filtration was found to be effective in avoiding the gravity segregation of PMMA. Numerous spherical pores with 100 \\micron in mean diameter were introduced in the composites by mixing PMMA, which was burned out during sintering. The shape, size and volume fraction of pores could be controlled by those of PMMA added to the composites. The bending strength of HAp/α-TCP composites depended strongly on the porosity; the strength decreased exponentially with increasing the porosity. These composites may demonstrate higher solubility and faster bone growth than HAp alone.