Fabrication and characterization of porous hydroxyapatite and biphasic calcium phosphate ceramic as bone substitutes

In the present study, the calcium phosphate powders (HAP, HAP-TCP) were produced by a precipitation technique involving the use of aqueous solutions of calcium nitrate and diammonium hydrogen phosphate. Preforms of calcium phosphate ceramics were produced by using a modified slip casting technique. Porosity in the cast and in the sintered ceramic was obtained through custom made PMMA beads similar to200-300 mum size. The green ceramic samples were prepared by suspending the apatite powder and PMMA beads in an aqueous medium stabilized with an acrylic deflocculant. Porous ceramics were obtained by sintering the polymer-free preforms for 2 hours at 1000degreesC to 1200degreesC. Pore size and pore size distribution as revealed by SEM analyses were appropriate for repair of cortical defects.