Bone-like Apatite Formation on Calcium Phosphate Ceramics in Different Kinds of Animal Simulated Body Fluid

Five kinds of simulated body fluid (SBF) were prepared according to the Ca2+ ions concentration in body fluids of human, dog, pig, rabbit and monkey. The cylindrical porous specimens of φ4×8mm were obtained by sintering the green block of biphasic calcium phos-phate(HA/TCP=70/30) at 1200℃. There were two kinds of porous specimens: dense pore wall and pore wall with micro pores. After 14-day immersion in SBF, bone-like apatite formed on the pore wall with micro pores while no apatite was observed on the smooth pore wall. The bone-like apatite grew faster in SBF of dog and rabbit than in other SBF. In animal experiment, the same phenomena were also observed: bone-like apatite formed faster on specimens implanted in dog and rabbit than in other animals. This sequence is different from the order of osteoinductivity of biphasic calcium phosphate ceramics implanted in these animals. The results show the formation of bone-like apatite on materials is an important factcr but not the only factor for their osteoinduction.