Influence of amorphous calcium phospahte on the properties of calcium phosphate based cements

Abstract

In the present study, the influence of amorphous calcium phosphate (ACP) on the properties ofƒnƒÑ- tricalcium phosphate (£TCP ) derived calcium phosphate cement (CPC) was investigated. Properties like setting time, formed apatite crystallite size and diametral tensile strength of ACP/£TCP based cement was studied. ACP powder was synthesized using rapid wet precipitation method from a precursor solution of calcium nitrate and ammonium dihydrogen phosphate. Synthesis of £TCP was carried out by the sold reaction between calcium carbonate and dicalcium phosphate anhydride at 1300 C followed by rapid quenching. £ TCP and ACP powder were synthesized phase purity was analysed using x-ray diffraction (XRD) and Fourier transform infra red (FTIR) spectra. Initial and final setting times of the cement pastes were measured at 37 ¢XC in humidity controlled incubator. The phase composition and microstructure of the set cements were investigated after 10 days in SBF using X-ray diffractometry and scanning electron microscopy. Diametral tensile strength of the set CPCs was measured using Universal Testing Machine. The £TCP-based cement exhibited longer setting times, a higher strength as compared to ACP added CPC. Addition of ACP to the £TCP based cement resulted in shorter setting times, but larger macroporosity and diminished diametral tensile strength. Moreover, well entangled hydroxyapatite crystals were observed in the microstructure of £TCP based CPC.