Surface Micro-Discharge Plasma for Multiple Teeth Bleaching: Efficacy, Mechanism and Safety

Abstract

Hydrogen peroxide (H₂O₂) is the commonly-used bleaching chemical in clinical practice, but its excessive concentrations can cause tooth damage. Atmospheric pressure cold plasma is considered a promising new technique for tooth bleaching. Surface micro-discharge (SMD) devices can generate large-scale plasma, which holds potential for treating multiple teeth simultaneously. However, research in this area remains limited. This study systematically evaluated the bleaching efficacy, mechanism and safety of SMD plasma treatment of multiple human tooth stain models. The results demonstrated that SMD plasma effectively whitens multiple teeth simultaneously, achieving a ΔE₀₀ value of 5.65 within 10 min. Its whitening efficacy surpasses that of the 10% H₂O₂ group. SMD plasma generates substantial reactive oxygen species, and the degradation efficiency of theaflavin can reach 99.59% within 5 min. Hydroxyl radicals and ozone serve as primary agents reacting with coloured molecules, cleaving chemical bonds and facilitating tooth whitening. Following SMD plasma treatment, the tooth surface temperature increased but remained within the acceptable range for the oral cavity. Meanwhile, the surface hydrophilicity declined, whereas surface roughness, microhardness and morphology remained largely unchanged. This study provides a crucial theoretical foundation for the application of SMD plasma in tooth whitening.