Killing of adherent oral microbes by a non-thermal atmospheric plasma jet

1 Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, Saarland University, Homburg, Germany 2 Leibniz Institute for Surface Modification, Leipzig, Germany 3 Vascular Biology Group, Fraunhofer Institute, Leipzig, Germany 4 Institute for Medical Biometry, Epidemiology and Medical Informatics, Saarland University, Homburg, Germany Correspondence Stefan Rupf stefan.rupf{at}uks.eu Received June 19, 2009 Accepted November 5, 2009 Atmospheric plasma jets are being intensively studied with respect to potential applications in medicine. The aim of this in vitro study was to test a microwave-powered non-thermal atmospheric plasma jet for its antimicrobial efficacy against adherent oral micro-organisms. Agar plates and dentin slices were inoculated with 6 log 10 c.f.u. cm –2 of Lactobacillus casei , Streptococcus mutans and Candida albicans , with Escherichia coli as a control. Areas of 1 cm 2 on the agar plates or the complete dentin slices were irradiated with a helium plasma jet for 0.3, 0.6 or 0.9 s mm –2 , respectively. The agar plates were incubated at 37 °C, and dentin slices were vortexed in liquid media and suspensions were placed on agar plates. The killing efficacy of the plasma jet was assessed by counting the number of c.f.u. on the irradiated areas of the agar plates, as well as by determination of the number of c.f.u. recovered from dentin slices. A microbe-killing effect was found on the irradiated parts of the agar plates for L. casei , S. mutans , C. albicans and E. coli . The plasma-jet treatment reduced the c.f.u. by 3–4 log 10 intervals on the dentin slices in comparison to recovery rates from untreated controls. The microbe-killing effect was correlated with increasing irradiation times. Thus, non-thermal atmospheric plasma jets could be used for the disinfection of dental surfaces.