Effect of nanoemulsion on dental unit waterline biofilm

Bacterial biofilm in dental unit waterlines (DUWLs) is a widespread problem and poses a potentially significant risk of infection to dental staff and patients. The present study investigates the level and composition of bacterial contamination of dental chair syringe waterlines and investigates the efficacy of a cetylpyridinium chloride-containing nanoemulsion disinfectant in reducing bacterial loads. Waterline biofilms exposed to nanoemulsion for 1 hour, 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours showed high reduction of colonies, and very low counts after 12 hours and 24 hours (67 colony-forming units/mL) were observed. Exposures for 48 hours and 72 hours showed no or few visible colonies (2 colony-forming units/mL). The nanoemulsion employed improves efficacy against microorganisms more than unemulsified components. DNA sequencing showed that the organisms in the waterline biofilm are primarily of soil or water origin. The findings indicate that nanoemulsion effectively disinfects waterlines to consistently meet the American Dental Association (ADA) recommendation.