Dynamic study of calcium phosphate formation on porous HA/TCP ceramics

Bone-like apatite formation on porous calcium phosphate ceramics was investigated in static simulated body fluid (SBF) and dynamic SBF at different flowing rates. The results of a 14-day immersion in static SBF showed that the formation of bone-like apatite occurred both on the surface and in the pores of the samples. When SBF flowed at the physiological flow rate in muscle (2 ml/100 ml.min), bone-like apatite could be detected only in internal surface of the pores of samples. The result that bone-like apatite formation could only be found in the pores when SBF flowed at physiological flow rate was consistent with that of porous calcium phosphate ceramics implanted in vivo: osteoinduction was only detected inside the pores of the porous calcium phosphate ceramics. This result implicates that the bone-like apatite may play an important role in the osteoinduction of Ca-P materials. The dynamic model used in this study may be better than usually used static immersion model in imitating the physiological condition of bone-like apatite formation. Dynamic SBF method is very useful to understand bone-like apatite formation in vivo and the mechanism of ectopic bone formation in calcium phosphate ceramics.