Table of Contents
ISRN Dentistry
Volume 2012, Article ID 295736, 6 pages
Research Article

In Vitro Antimicrobial Effect of a Cold Plasma Jet against Enterococcus faecalis Biofilms

1Department of Electrical Engineering-Electrophysics, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
2Electron Microscopy and Advanced Imaging Center, House Ear Institute, Los Angeles, CA 90057, USA
3Endodontic Department, School of Dentistry, Loma Linda University, Loma Linda, CA 92354, USA
4Center for Genomic Sciences, Allegheny-Singer Research Institute, Pittsburgh, PA 15212, USA

Received 20 September 2011; Accepted 27 October 2011

Academic Editors: F. Cairo and G. Dahlen

Copyright © 2012 Chunqi Jiang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The hypothesis that a cold plasma jet has the antimicrobial effect against Enterococcus faecalis biofilms was tested in vitro. 27 hydroxyapatite discs were incubated with E. faecalis for six days to form a monoculture biofilm on the disc surface. The prepared substrata were divided into three groups: the negative control, the positive control (5.25% NaOCl solution), and the plasma treatment group. Resultant colony-forming unit counts were associated with observations of bacterial cell morphology changes using scanning electron microscopy (SEM). Treatment of E. faecalis biofilm with the plasma and 5.25% NaOCl for 5 min resulted in 93.1% and 90.0% kill ( 𝑃 < 0 . 0 0 0 1 ), respectively. SEM detected that nearly no intact bacteria were discernible for the plasma-exposed HA disc surfaces. The demonstrated bactericidal effect of the plasma with direct surface contact may be due to the enhanced oxidation by the locally produced reactive plasma species.