Feasibility of nonthermal atmospheric pressure plasma for intracoronal bleaching J. K. Park 1, *, S. H. Nam 2, *, H. C. Kwon 3 , A. A. H. Mohamed 4 , J. K. Lee 3 & G. C. Kim 2 1 Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea; 2 Department of Oral Anatomy, School of Dentistry, Pusan National University, Yangsan, Korea; 3 Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang, Korea; and 4 Department of Physics, Faculty of Science, Taibah University, Almadinah Almunawwarah, Saudi Arabia Abstract Park JK, Nam SH, Kwon HC, Mohamed AAH, Lee JK, Kim GC. Feasibility of nonthermal atmospheric pressure plasma for intracoronal bleaching. International Endodontic Journal, 44, 170–175, 2011. Aim To investigate the effect of nonthermal atmo- spheric pressure plasma on intracoronal tooth bleach- ing in blood stained human teeth. Methodology 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 (DE) 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. Results 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 DE values of group 1 and group 2 were 9.24 (0.37) and 4.47 (1.62), respectively, at 30 min. Conclusions The application of nonthermal atmo- spheric pressure plasma to intracoronal bleaching could be a novel and efficient therapy in the bleaching of haemorrhagically stained teeth. Keywords: blood stained human teeth, hydrogen peroxide, intracoronal bleaching, nonthermal atmo- spheric pressure plasma. Received 31 August 2010; accepted 18 October 2010 Introduction Aesthetics of teeth, including colour, are of great importance to patients. Recently, there has been increasing interest in tooth bleaching because white teeth are being retained longer (Greenwell 2001). Tooth discolouration results from various and multi- faceted causes that are classified into extrinsic and intrinsic discolouration (Watts & Addy 2001). Extrinsic discolouration is caused by the deposition of external chromogens such as food, beverages, and tobacco on the tooth surface. Intrinsic discolouration occurs when the chromogens are deposited within the bulk of the tooth, usually the dentine, and caused by systemic or pulpal factors (Addy & Moran 1995). The main intrinsic factors are pulp haemorrhage, decomposition of pulp, bacteria and their products, tetracycline, pulp necrosis, intracanal medicaments, some endodontic filling materials, and metallic restorations (Plotino et al. 2008). Intracoronal bleaching (internal, non-vital bleach- ing) has been an accepted clinical procedure in dentistry for over 100 years (Kirk 1893, Spasser Correspondence: Gyoo Cheon Kim, Department of Oral Anat- omy, School of Dentistry, Yangsan Campus of Pusan National University, Beoameo-ri, Mulgeum-eup, Yangsan-si Gyeong- sangnam, 626-870, Korea (Tel.: +82 (10) 5251 8214; fax: +82 (51) 510 8241; e-mail: ki91000m@pusan.ac.kr). *These authors contributed equally to this work. doi:10.1111/j.1365-2591.2010.01828.x International Endodontic Journal, 44, 170–175, 2011 ª 2010 International Endodontic Journal 170