α-TCP cements prepared by syringe-foaming: Influence of Na2HPO4 and surfactant concentration

The lack of intrinsic open porosity in calcium phosphate cements slows down the resorption rate and bone ingrowth when implanted In Vivo. In this study, macroporous structures were obtained by mixing alpha-TCP cement with a foamed liquid phase containing different concentrations of sodium hydrogen phosphate and a nonionic surfactant. The cement paste was prepared by hand mixing in a novel system of two syringes connected by a tube. Two different liquid to powder (L/P) ratios were used to prepare the cement paste. The cement samples showed open macropores with diameters > 100 mu m. The specimens prepared with lower L/P ratio showed smaller porosity, macroporosity and pore size distribution. The cohesion of the cement paste in liquid solutions was assessed by adding 2 wt% sodium alginate to the liquid phase. This study suggests that the final macrostructure of the foamed cements can be controlled by varying the phosphate and surfactant concentrations in the liquid phase and the L/P ratio.