Titanium-hydrogen peroxide interaction: model studies of the influence of the inflammatory response on titanium implants.

In vitro studies of titanium and TiO2 as well as other metals were carried out to investigate the role of these metals in the inflammatory response through the Fenton reaction. The TiOOH matrix formed traps the superoxide radical, so that no or very small amounts of free hydroxyl radicals are produced. Ellipsometry and spin trapping with spectrophotometry and electron spin resonance (ESR) were used to study the interaction between Ti and H2O2. Spectrophotometry results indicated that Ti, Zr, Au and Al are low free OH-radical producers. We propose a new model for the titanium-tissue interface where the oxidized titanium surface is covered with a hydrated TiOOH matrix after the inflammatory reaction. This matrix is suggested to possess good ion exchange properties, and extracellular components may interact with the Ti(IV)-H2O2 compound before matrix formation. The TiOOH matrix is formed when the H2O2 coordinated to the Ti(IV)-H2O2 complex is decomposed to water and oxygen. Superoxide (O2-) may be bound therein. The oxide layer initially present may be partly reformed to a TiOOH matrix due to the interaction with hydrogen peroxide.