Effects of the Composition of the Bioactive Composite Calcium Phosphate Cement on Its Behavior in the Solution

In this paper, the hydration product of calcium phosphate cement with bioactive glass containing Si was used to investigate the effect of chemical composition on its bioactivity. The variation of concentrations of Ca2+, P and Si in TE solution complemented with electrolytes typical for plasma (TEE) and the formation of amorphous calcium phosphate layer on the surface of the materials were investigated by immersing the designed materials in TEE solution in vitro. The results showed that the composition of the bioactive composite CPC greatly affected its behavior in the solution and the formation of bioactive apatite. After immersed in TEE solution, the Ca ions were uptaken for all the samples, showing the decreases of Ca concentration during the entire duration, but the concentration of P ions increased sharply at the initial stage, and then decreased due to the formation of amorphous calcium phosphate layer on the surface of the materials. FTIR revealed that the layer was poorly crystallized Ca-deficient carbonate apatite. The thickness of the layer was more than 12 um, which layer was composed of rod-like apatite with directional arrangement. All the data obtained would be useful for the design and optimization of the orthopedic degradable implant inorganic materials.