Novel thooth bleaching technique using non-thermal atmospheric-pressure plasmas

Hydrogen peroxide (H₂O₂) is a widely used tooth bleaching material that is effective and safe. However, the exact mechanism of bleaching action by H₂0₂ is not completely understood. One possible mechanism is that H₂O₂ breaks down to produce oxygen radicals, which attack organic pigment molecules, and causes bleaching. In-office bleaching systems use from 30 to 44% H₂O₂ bleaching gel and a high-intensity light source. The light source may enhance bleaching by heating the H₂0₂ and consequently accelerating bleaching, but this mechanism has not been confirmed yet. In this study, we demonstrate a tooth bleaching procedure that uses room-temperature plasma, instead of a light source in an in-office H₂0₂ bleaching system. Extracted human teeth were used in these in vivo experiments. All the teeth were sectioned into two species to be used in two groups; experimental group and control group. The experimental group was treated by 28% of a H₂0₂ with a plasma jet for 10 minutes, while control group was treated by H₂0₂ alone for the same time. Removal of the tooth surface protein was proved through scanning electron microscope images and Ponceau staining method. We had analyzed the bleaching results by comparing the overall color changes of the teeth photos which were taken before and after these treatments. Combining plasma and H₂O₂ improved the bleaching efficacy by a factor of three compared to using H₂O₂ alone. Tooth surface proteins were noticeably removed by plasma treatment. When a piece of tooth was added to a solution of H₂O₂ as a catalyst, the production of -OH after plasma treatment was 1.9 times greater than when using H₂O₂ alone. In conclusion, the plasma irradiation enhanced the tooth bleaching effect t- rough the removal of tooth surface proteins and prominently enhanced. OH generation reaction from H₂O₂.