Antibacterial effects of liquid discharge cold plasma on Enterococcus faecalis planktonic cultures and biofilms: an in vitro study of root canal treatment

Although many researchers have studied the antibacterial effects of gas discharge plasma in root canal disinfection, there are few studies on the potential of liquid discharge plasma in root canal disinfection. This study aimed to investigate the antibacterial effects of liquid discharge cold plasma (LDCP) on Enterococcus faecalis (E. faecalis) planktonic cultures and four-week-old root canal biofilms. Antibacterial efficacy was determined by the colony-forming unit method. Changes in the viability and surface morphology were studied by confocal laser scanning microscopy and scanning electron microscopy, respectively. The results showed that LDCP treatment had a significant antibacterial effect on planktonic E. faecalis, and had a better antibacterial effect on biofilms than 0.2% chlorhexidine treatment. The normal spherical structure of E. faecalis dissociated, and biofilm architectures were destroyed after LDCP treatment. This work opens doors to the potential application of using liquid discharge plasma devices for root canal treatment.