Cold Atmospheric Pressure Plasma Is Effective against P. gingivalis (HW24D-1) Mature Biofilms and Non-Genotoxic to Oral Cells

Abstract

The effects of helium cold atmospheric pressure plasma (He-CAPP) jet on Porphyromonas gingivalis (HW24D-1) biofilm, on human gingival fibroblasts (HGF) and human gingival keratinocytes (OBA-9) were assessed. Standardized suspension of P. gingivalis was obtained, and biofilms were grown anaerobically for 48 h. After exposition to He-CAPP, the biofilm viability was evaluated by XTT assay. HGF were grown at 37 °C, in an CO2 chamber in DMEM, while OBA-9 cells were cultured in keratinocyte serum-free medium. After 24 h, plates were exposed to He-CAPP for 1 to 7 min. Plasma was generated using a commercial AC power supply with amplitude modulated signal (voltage amplitude of 20 kVp-p, frequency of 31.0 kHz and duty cycle of 22%). The corresponding discharge power was 0.6W at He flow rate of 1 L/min. DNA damage was accessed by static cytometry. Data were analyzed by GraphPad Prism (p < 0.05). Significant reductions in P. gingivalis viability in relation to non-treated groups were detected (p < 0.0001), directly proportional to exposure time. Treated groups were slightly aneuploid after 5- and 7-min treatment in HGF, and for 3 min in OBA-9 cells, with 1.2 DNA index mean. Helium cold atmospheric pressure plasma jet showed inhibitory effect on P. gingivalis mature biofilm and was not genotoxic for epithelial gingival cells and human oral fibroblasts.