Disinfection of Dental EquipmentInactivation of Enterococcus mundtii on Stainless Steel and Dental Handpieces using Surface Micro-Discharge Plasma

Cold atmospheric plasma produced by a surface micro discharge (SMD) device was used to investigate the bactericidal efficacy for Enterococcus mundtii inoculated and dried on stainless steel and dental handpieces. The novelty of this approach can be explained by the used setup incorporating a circular plasma system. The circular plasma system produces reactive plasma species, which are transported through the narrow cavities of a dental handpiece into a separate treatment chamber and which are subsequently recycled and transported back to the SMD electrode. To investigate the efficacy of this circular plasma setup, stainless-steel plates inoculated with E. mundtii were placed in the treatment chamber and treated with plasma. The results show that a 5 log reduction in bacterial number can be achieved within only 15 min of plasma treatment time, although the plasma species had to pass the narrow channels of the dental handpiece before entering the treatment chamber. First results with E. mundtii inoculated directly on the outer side of the dental handpiece showed a 2 log reduction within 15 min of plasma application. Further investigations targeting this latter issue are nevertheless necessary to investigate the plasma treatment time to achieve full disinfection also on dental handpieces.