Abstract
Calcium phosphate paste (CPP; major crystalline phases, α-Ca3 (PO4) 2 and Ca4 (PO4) 20) was mixed with 1.0, 2.0 and 9.1 mass% of collagen type I solution (Col (I) -S); the mixtures were lyophilized at-7°C for 24 h and then ground. The resulting powders were kneaded with fresh blood and mixing liquid to form hardened bodies. These hardened bodies were immersed into the simulated body fluid (SBF) at 37.0 ± 0.2°C for desired periods. The amount of the mixing liquid that could be added to the CPP powder with Col (I) -S addition was examined without the addition of blood. The reciprocal ratio of powder to liquid, i.e., (P/L) -1, increased to 0.77; this value was approximately 38% higher than the case of CPP powder with Col (I) granules (Col (I) -G) with sizes below 150 pm. The immersion of CPP specimen with 9.1 mass% of Col (I) -S and blood addition (P/L ratio : 1.7) into the SBF for 7 d revealed that the changes of calcium phosphates in the CPP to hydroxyapatite (Ca10 (PO4) 6 (OH) 2) were slightly retarded. The total porosity and compressive strength of this specimen were 66.5 ± 1.5% and 4.28 ± 0.04 MPa, respectively. The SEM investigation revealed that the grains were coated with collagen and appreciable difference in microstructure was observed. compared to the case of CPP specimen with Col (I) -G addition.
