Plasma Sterilization Effectively Reduces Bacterial Contamination in Dental Unit Waterlines

Abstract

Objective. To investigate the effectiveness of plasma sterilization in reducing bacterial contamination and controlling biofilms in dental unit waterlines.Materials and Methods. Ten identical dental chair units (DCUs) were used. Five DCUs were installed with an automated plasma sterilization system (PSS) and the other five were kept as nontreated controls (CTL). Water flushed from the airotor line served as the output water of the dental unit waterlines (DUWLs). Water samples were collected at the beginning and on a weekly basis for 4 months. Water was analyzed for bacterial contamination (CFU/mL). Scanning electron microscopy (SEM) was used to investigate the amount of biofilm in the waterlines. Biofilm viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. All statistical analyses were performed using the Mann–WhitneyUtest. A value ofp<0.05was considered significant.Results. The DCU output water was found to be heavily contaminated with bacteria. Plasma sterilization effectively reduced bacterial contamination from an average of 212 CFU/mL to 8 CFU/mL. During the entire period of 4 months, the level remained below 500 CFU/mL, the standard level recommended by the Centers for Disease Control and Prevention (CDC) of the USA. The reduction in the bacterial count was significant compared with the CTL group (p<0.05). Plasma sterilization could not eradicate the existing biofilms in the waterlines, and it did reduce biofilm mass and viability. Moreover, treatment with plasma sterilization did not induce a change in the composition of microorganisms, as analyzed by Gram staining.Conclusion. Plasma sterilization, which is part of electrochemically activated water, effectively reduces bacterial contamination and reduces biofilms in dental unit waterlines.

Disinfection methods of dental unit waterlines contamination: a systematic review

“…Electrolysed water might be an alternative choice and this needs further investigation [71]. In addition, plasma sterilization is used to break down water molecules (H 2 O) into hydrogen ions (H + ), oxygen ions (O 2− ), and in the meanwhile to produce ozone (O 3 ), hydroxyl ions (OH − ), hypochlorous acids (HClO) and hydrogen peroxide (H 2 O 2 ) [73]. The ions and molecules resulting from plasma sterilization also possess strong antibacterial effects [73].…”

Culturomic and quantitative real‐time‐polymerase chain reaction analyses for early contamination of abutments with different surfaces: A randomized clinical trial

“…Different treatments, such as steam vapor or ultrasound baths and UV lights are reported to minimize this contamination 10 . Plasma of argon demonstrated to improve the decontamination effects together with an increase of material surface energy 11 . This led to a decrease of bone resorption/loss, 12,13 but the increased hydrophilicity, may favor microbiological contamination 14 …”

“…10 Plasma of argon demonstrated to improve the decontamination effects together with an increase of material surface energy. 11 This led to a decrease of bone resorption/loss, 12,13 but the increased hydrophilicity, may favor microbiological contamination. 14 Polymerase chain reaction (PCR) was discovered by Mullis and colleagues in 1986 as a consequence of the development of molecular biology in the 1980s.…”

Evaluation of the simulator with automatic irrigation control system designed for countermeasures of internal contamination in dental unit water lines

“…On the other hand, there have already been several studies about biofilm formation using either DUWLs of active dental chair unit or unique model [8,9,10,11,12]. In addition decontamination methods for water pollution have been reported, not only in the field of dentistry but also in the research field on general water pipes [13,14].…”