Fabrication and characterization of chelate-setting β-tricalcium phosphate cements with enhanced bioresorbability

A novel chelate-setting β-tricalcium phosphate (β-TCP) cement with anti-washout properties have been fabricated previously. This cement has been set on the basis of chelating ability of inositol phosphate (IP6). In this study, the ball-milling and surface-modification conditions of starting β-TCP cement powders were optimized in terms of bioresorbability. Starting powders were prepared by simultaneously ball-milling at 300 rpm for 3 h with 1 mm diameter ZrO₂ beads and surface-modifying with 40 cm³ of 3000 ppm IP6 solution. The resulting starting powder was consisted of β-TCP single phase, and had high specific surface area of 48.3 m m²·g^-1. Cement pastes were prepared by mixing the starting powder and the aqueous solution composed of 2.5 mass% sodium hydrogen phosphate, 1.5 mass% citric acid and 1.0 mass% sodium alginate at a powder/liquid ratio of 1/0.90 [g·cm^-3] for 2 min. After setting in pure water for 72 h, compressive strength of the cement specimens was higher than that of human cancellous bone. Dissolution rate of Ca²⁺ ions was measured by according to Japanese Industrial Standard T 0330-3. The results of Ca²⁺ ions dissolution rate test demonstrated that the cement specimens derived from the above starting powder were the highest dissolution rate among examined ones. This cement would be expected as bone fillers with high bioresobability.