INFLUENCE OF TITANIUM-OXIDE AND TITANIUM PEROXY GEL ON THE BREAKDOWN OF HYALURONAN BY REACTIVE OXYGEN SPECIES

The molecular events occuring at the interface between titanium and co nnective tissue were investigated in order to help explain the unique biocompatible properties of titanium implants and their successful oss eointegration into bone tissue. In this study the influence of commerc ially pure titanium and titanium peroxy gets on the breakdown of the c onnective tissue component and serum derived factor, hyaluronan, by re active oxygen species (ROS), produced during the insertion of an impla nt in vivo, was examined. Hyaluronan breakdown was monitored in vitro in the presence of a hydroxyl radical flux, generated in the presence and absence of titanium powder and discs. Parallel studies examined th e breakdown of hyaluronan by hydroxyl radicals in the presence of a ti tanium peroxy gel, prepared by incubation of the titanium powder or di scs in concentrated hydrogen peroxide. The hyaluronan degradation prod ucts were separated according to their hydrodynamic size by gel exclus ion chromatography. Similarly, experiments were also performed examini ng the degradation of 2-deoxy-D-ribose by a hydroxyl radical flux in o rder to demonstrate the detrimental potential of the hydroxyl radicals and to provide a measure of the effectiveness of titanium and titaniu m peroxy gels as scavengers of ROS. Titanium reduced the harmful effec ts of the hydroxyl radicals on the breakdown of hyaluronan, presumably acting as a scavenger for the reactive species, possibly by absorbing them into its surface oxide layer, which spontaneously forms on the s urface. In contrast, the formation of a titanium peroxy gel from the t itanium powder or on the surface of titanium discs enhanced breakdown of both the hyaluronan chains and 2-deoxy-D-ribose. The implications o f these findings with regards to the biocompatible nature of the titan ium and the ability of these implants to successfully osseointegrate a re discussed. Crown (C) 1996 Published by Elsevier Science Limited