Cement formulations in the calcium phosphate H20-H3PO4-H4P207

Despite numerous reports of calcium phosphate cement materials, a calcium cement that sets to form a matrix consisting of a pyrophosphate phase has not been reported. The formulation of such a material from the mixture of alpha-tricalcium phosphate (TCP), beta-TCP, or tetracalcium phosphate with a solution containing pyro- and orthophosphoric acid is reported in this study. The effects of liquid and solid compositions on the setting times, compressive strengths and phase compositions of the resultant cements were investigated. It was found that cements could be produced that set to form up to 28 wt% dicalcium pyrophosphate, which appeared by comparison with Rietveld refinement and chemical methods to be entirely amorphous in nature. The solubilities of the different solid components were shown to have a marked effect on the composition of the cements. The strongest cement formulations exhibited compressive strengths comparable with those previously reported in the literature for brushite cements and set within clinically relevant time scales. This class of cement would appear to demonstrate potential as a bone replacement material.