Feasibility of nonthermal atmospheric pressure plasma for intracoronal bleaching. 
To investigate the effect of nonthermal atmospheric pressure plasma on intracoronal tooth bleaching in blood stained human teeth.  Forty extracted single-root and blood stained human teeth were used.  The teeth were randomly divided into two groups (n=20): group 1 received 30% HP activated by nonthermal atmospheric pressure plasma in the pulp chamber for 30 min, whilst group 2 received 30% HP alone in the pulp chamber for 30 min.  The overall colour changes (ΔE) were assessed using the Commission Internationale de L'Eclairage (CIE) Lab Colour System.  The data were analysed using Student's t-test to determine the significant differences.  The temperature of all teeth was maintained at approximately 37 °C during plasma bleaching.  The plasma treatment with 30% HP resulted in significantly higher bleaching efficacy compared to 30% HP alone in discoloured teeth (P<0.05).  The average ΔE values of group 1 and group 2 were 9.24 (0.37) and 4.47 (1.62), respectively, at 30 min.  The application of nonthermal atmospheric pressure plasma to intracoronal bleaching could be a novel and efficient therapy in the bleaching of haemorrhagically stained teeth.