An atmospheric pressure non-thermal plasma needle for endodontic biofilm disinfection

Summary form only given. A pulsed, needle-like plasma jet was generated for root canal disinfection. Up to 3 cm long, <;1 mm in diameter, the plasma needle was powered with ~100 ns, 1-2 kHz, multi-kilovolt electric pulses and filled with 1 standard liter per minute He/(1%)O₂ flow. This low power, pulsed, plasma jet consists of ionization fronts propagating away from both electrodes at speeds of the order of 10⁷ cm/s. Plasma treatment of Enterococcus faecalis biofilms on hydroxyapatite (HA) discs for 5 min resulted in 93% kill. Scanning electron microscopy revealed nearly no intact bacteria were discernible for the plasma exposed HA disc surfaces. Similar plasma jets were applied for salivary biofilm-colonized root canal disinfection. After 5 min plasma treatment, removal of the biofilm for a depth of 1 mm and cleared dentinal surfaces were observed. The demonstrated antimicrobial effect of the plasma against endodontic biofilms suggests that the non-thermal plasma-based technology could be a possible alternative or supplement to existing protocols for root canal disinfection.