Characterization by electron spin resonance spectroscopy of reactive oxygen species generated by titanium dioxide and hydrogen peroxide.

The influence of reactive oxygen species (ROS) on the surface modification of titanium implants and osseointegration is unclear. The aim of this study was to evaluate the ability of titanium dioxide (TiO2) to generate ROS in the presence of H2O2 and to determine whether any ROS thus generated play a role in osseointegration, as measured by electron spin resonance (ESR) spin-trapping with 5,5-dimethyl-1-pyrolline-N-oxide (DMPO). We demonstrate that TiO2 together with H2O2 generated hydroxyl radicals (HO*), as shown by a time-dependent increase in the spin concentration of the ESR signal for the DMPO-OH spin adduct, indicating HO* generation. Interestingly, irradiated TiO2 with H2O2 generated the superoxide (O2*-), as shown by an increase in the spin concentration of the signal for the DMPO-OOH spin adduct, indicating O2*- generation during the period of irradiation (0-5 min). These results suggest that ROS generated from the TiO2 layer may be involved in creating appropriate conditions for the osseointegration of dental implants into alveolar bone tissues.