How does existing bone bond to prosthetic implants such as artificial joints?
Examining interactions between the surface of the implant (made of silica ceramic) and the dissolved ions that make up bone can help design prosthetic materials that will allow quicker bone-implant bonding and faster post-operative recovery times for patients. Silica bioceramics are used as prosthetic bone and dental implants because they promote apatite formation at their surfaces when immersed in simulated body fluid (SBF) of composition similar to blood plasma. Apatite formation occurs in stages but the reaction pathway remains unresolved. (Fig. e) We have used molecular orbital calculations to model the interactions of Ca2+, H2PO41-, HPO42- and H2O with bioceramic surface sites to determine the reaction sequence for apatite nucleation at bioceramic surfaces and the nature of calcium and phosphate sorption on silica (Sahai and Tossell, 2000). Fig. e Surface sites were represented by [Si7O12H10], [Si4O8H8], and [Si3O6H6] (Fig. f). Predicted reaction energies, vibrational frequencies,
