APATITE FORMATION ON SILICA-GEL IN SIMULATED BODY-FLUID - EFFECTS OF STRUCTURAL MODIFICATION WITH SOLVENT-EXCHANGE

The prerequisite for glasses and glass-ceramics to bond to living bone is the formation of biologically active bone-like apatite on their su rfaces. It has been shown that even a pure silica gel forms the bone-l ike apatite on its surface in a simulated body fluid. In the present s tudy, pore structure of silica gels prepared by hydrolysis and polycon densation of tetraethoxysilane in an aqueous solution containing polye thylene glycol was modified by 1M HNO3, and 0.1M and 1M NH4OH solution treatments. The three kinds of resultant gels all contained large amo unts of silanol groups and trisiloxane rings, but differ greatly in po re structure of nanometre pore size. Irrespective of these differences , all the gels formed the bone-like apatite on their surface in the si mulated body fluid. It was speculated that a certain type of structura l unit of silanol groups, which is easily formed in the presence of th e polyethylene glycol, is effective for the apatite formation. (C) 199 8 Chapman & Hall.