Preparation of a biphasic porous bioceramic by heating bovine cancellous bone with Na4P2O7 · 10H2O addition

Sintered bovine cancellous bone exhibited excellent biocompatiblity, high porosity and have an interconnecting porous structure allowing for bone ingrowth. However, the main mineral constitution of sintered bovine bone—hydroxyapatite (Ca10(PO4)6(OH)2, HAP) seems to be too stable in vivo. For improving its bioactivity, the calcined bovine bone—removing the organic substance by burning process—with different quantities of sodium pyrophosphate (Na4P2O7 · 10H2O, NP) addition was heated to a high temperature to transform its crystalline phase constitution from HAP into TCP/HAP biphasic or other multiphasic structures. Results revealed that the calcined bovine bone without NP addition, exhibited a pure form of HAP characterized pattern during heating. Its thermal behavior was similar to stoichiometric HAP, it gradually lost its OH- ions and transformed into oxyhydroxyapatite at high temperature. After being doped into calcined bovine bone, NP would react with HAP to form βTCP and NaCaPO4 around 600°C. At 900°C, doped NP would completely react with HAP and the NaCaPO4 would further react with HAP to form more βTCP in the system. With NP increasing in the calcined bovine bone, HAP would gradually convert into different crystalline phase compositions of TCP/HAP, TCP/HAP/NaCaPO4 or TCP/NaCaPO4 at high temperature. By heating calcined bovine cancellouse bone with different quantities of NP we could obtain different crystalline phase compositions of natural porous bioceramic in this study.