A novel method of tooth whitening using a cold plasma micro-jet driven by direct current at atmospheric-pressure air

Summary form only given. Eating habits, smoking, drugs and chemicals can cause undesirable staining of teeth. Tooth bleaching has become a popular dental practice to remove stains from the tooth surface for aesthetic or therapeutic purposes. Clinical teeth-whitening involves the application of H₂O₂ gel (35%), which might be harmful after prolonged use.In this paper, we present tooth-whitening results of extracted teeth treated by a direct-current, cold, atmospheric-pressure air plasma micro-jet (PMJ). Saline solution (0.9% NaCl) was applied to teeth during the treatments to keep the tooth surface moist. Compared to our previous work of teeth whitening using a PMJ assisted by H₂O₂ gel1, a significant improvement of tooth-whitening effect was observed. Atomic oxygen emissions were observed in end-on optical emission spectroscopy. Strong OH radical signals were detected by electron spin resonance. The tooth surface temperature was monitored and found to remain below 40° C. The surface properties of the teeth were evaluated by SEM and a microhardness test. This novel tooth-whitening approach, especially the elimination of the H₂O₂ gel, might revolutionize clinical tooth whitening.