Relationship Between Porous Structure Of Porous Calcium Phosphate Biphasic Ceramics And Its Osteoinductivity

The porous structure of porous calcium phosphate ceramics is one of the essential conditions that resulting in osteoinductivity. Therefore, it is of great importance both in theory and practice that the relationship between the porous characteristics of porous calcium phosphate ceramics including aperture size, aperture distribution, aperture shape and porosity and so on and its biological function such as osteoinductivity is studied.In this paper, the porous structure of HA/β-TCP biphasic ceramics was improved by adding microporous porosifer and the porous characteristic (porosity, aperture size, and distribution etc.) was quantitatively determined by the method of Archimedes and Mercury Porosimetry. Then, we calculated the Fractal dimension by the method of Fractal geometry in the first so that the penetrability of the pore was evaluated. By means of a series of experiments including protein adsorption experiment, bone-like apatite formation experiment by immersing in static SBF and in dynamic SBF. The interaction between porous calcium phosphate ceramics and protein as well as the relationship between the porous characteristic of porous calcium phosphate ceramics and formation of bone-like apatite, were discussed in order to provide the theory gist for understanding its bone-formation mechanism in vivo. The result showed that the perforation ability and the size of perforating passage of HA/β–TCP porous ceramics have a large influence on the formation of bone-like apatite, in which the size should be larger than 20μm.The specimens with microporous porosifier and without microporous porosifier were investigated by cell culture in vitro and observed the attachment and growth of the cell. The biocompatibility of HA/β-TCP ceramics and the influence that the porous structure on its osteoinduction were studied by determining cell multiplication using MTT colorimetry, observing cell growth in the surface of specimens with SEM and observing cell subsistence in the surface of specimens by the method of fluorescence decoration. The results showed that when co-cultured with HA/β-TCP ceramics, cells firstly attached the edge of macropores in the surface of specimens and the wall of the macropores which possessed micropores in its wall, and grew into the micropores, then packed the macropores wholly during further culture period. At last, the ceramics were almost covered with cells. It indicated that the porous structure of the ceramics had important effect upon its osteoinduction.