抄録
A high concentration of hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) is commonly used as a dental bleaching agent. The mechanism of tooth bleaching is that the reactive oxygen species (ROS), especially hydroxyl radical (HO⋅), derived from H2O2 in the bleaching agent remove the color of teeth due to decomposition of organic substances. It has been reported that oxidative stress induced by ROS such as HO⋅ could be involved in various oral diseases. Thus, H2O2 has been shown to be a risk factor for oral tissue injury during bleaching treatment. However, questions remain about the effects of ROS generated from bleaching treatment in detail. Electron spin resonance (ESR) is recognized as one of the most powerful techniques available for the detection of ROS in tissues and cells. We previously developed an ESR-based technique for the detection of ROS reactions in biological systems. In this study, we confirmed O2⋅- generated from a low concentration of H2O2 (0.3%) /TiO2 with irradiation of UV light. It was observed that O2⋅- production from H2O2 (0.3%) /TiO2 increased in a time-dependent manner of UV light irradiation. Both the L value and ΔE*ab value rose in H2O2 (0.3%) /TiO2 with irradiation of UV light. These results suggest that a low concentration H2O2/TiO2 system could be applied more safely due to the formation O2⋅- but not HO⋅ as a risk factor for bleaching. In addition, the ESR technique would be useful for characterizing ROS for dental bleaching agents.
