Solution property of calcium phosphate cement hardening body

In this paper, the solution property of calcium phosphate cement (CPC) hardening bodies with various ratios of calcium to phosphate were studied. The solution property included solubility and behavior in simulated blood phosphoric acid solutions with selected initial concentrations at 37°C. When the ratios of calcium to phosphate were 1.67, 1.60, 1.55, 1.50, the solubility products, -log K_sp, were 99.2-102, 94.7-94.8, 89.6-90.5, 85.5-86.4, respectively. All these were significantly bigger than the values reported by the references due to the low crystallinity and calcium deficiency in the calcium phosphate cement hardening body. When CPC with Ca/P = 1.50 was immersed in fixed volumes of simulated blood plasma, both the calcium and phosphate concentrations in the solution increased, while for the samples with a ratio of 1.67, the concentrations decreased. These results showed that the simulated blood plasma was supersaturated when Ca/ P= 1.67 but unsaturated Ca/P = 1.50. It was deduced that when CPC was implanted in the bodies, the specimen with the ratio of 1.5 was degraded faster than with the sample of 1.67.