2020 Volume 29 Issue 3 Pages 173-182
Biphasic calcium phosphate (BCP) cement, consisting of an α-tricalcium phosphate-tetracalcium phosphate as the only solid phase and a calcium phosphate solution (Ca-P soln) as the liquid phase, was formerly reported. The BCP cement was easy to prepare, and was expected to show desired handling properties and to form hydroxyapatite (HA) for clinical applications. The objective of the study was to evaluate physical properties and HA formation of the BCP cement. The solid phase of the cement was a BCP (Ca/P of 1.8) prepared in a furnace and ground to a median size of 9.96µm. The liquid phase of the BCP cement consisted of an acidic Ca-P soln, which was produced by mixing phosphoric acid with calcium carbonate (CaCO3) and diluted 3.0-fold, 3.5-fold, 4.0-fold with H2O. Additionally, trisodium citrate anhydrous and polyvinylpyrrolidone were included as a water reducing agent and washout resistance enhancer, respectively. Cement powder and liquid were mixed (P/L=3.0) to produce samples for setting time, diametral tensile strength (DTS) and compressive strength (CS) measurements. X-ray powder diffraction (XRD) analyses and microscopic observations by FE-SEM and atomic force microscope (AFM) were also performed to identify HA conversion in set samples with time chronologically. BCP cement showed good washout resistance when immersed in water. The setting times (n=5) were 3.0-fold: 5.24±0.01min, 3.5-fold: 7.39±0.01min and 4.0-fold: 9.06±0.01min at 25±1°C. Differences were apparently existed between each sample (p<0.05). One-day wet DTS (n=5) values were 3.0-fold: 7.07±0.51MPa, 3.5-fold: 5.98±0.91MPa and 4.0-fold: 5.07±0.51MPa and CS (n=5) values were 3.0-fold: 46.58±3.21MPa, 3.5-fold: 47.75±2.55MPa and 4.0-fold: 45.53±1.97MPa. No difference was exhibited between DTS results for each sample except between 3.0-fold and 4.0-fold samples (p<0.05), and CS results showed no apparent difference existed among all samples (p<0.05). XRD analyses showed that BCP cement mostly converted to HA and microscopic features exhibited that HA crystals were clearly observed on surfaces of the BCP-cement at 24hours after mixing. The newly developed BCP cement was found to have adequate physical properties and HA formation for clinical use.