Title: Assessment of Water Quality Measures and Bacterial Contamination in Dental Water Systems
Samantha Howell (Presenter)
University of Detroit Mercy School of Dentistry
Kori Fetner, University of Detroit Mercy School of Dentistry
Rachel Ferree, University of Detroit Mercy School of Dentistry
Reginald Westley, University of Detroit Mercy School of Dentistry
Joshua Thomson, University of Detroit Mercy School of Dentistry
Objectives: Bacterial contamination is readily detected in dental unit water lines (DUWLs) due to the formation of biofilms containing multiple microbial species. These biofilms may harbor human pathogens and pose a public health concern. Precautions and guidelines are set in place to ensure bacterial levels are maintained below Centers for Disease Control and Prevention (CDC) and American Dental Association (ADA) standards (<500CFU/mL). The aim of this study was to assess the efficacy of current established preventative guidelines in a large dental clinic by determining the microbial burden in the bottle-fed water systems.
Methods: The guidelines included emptying the bottle reservoirs at the end of every clinic session, the utilization of straw filters to reduce microbial entry into the water lines from the reservoir, and flushing lines at the beginning and end of each clinic day for one minute. Biocontamination of the DUWL was assessed by monitoring ATP levels and measuring total heterotrophic bacteria plate counts (HPCs) in the water reservoir bottles, as well as from air/water syringes before and after mandated flushing of residual water.
Results: Our findings confirm statistically significant microbial contamination (p-value <0.05), higher than CDC/ADA standards within the bottle reservoirs according to ATP levels and HPC. Microbial contamination was also detected within the lines leading to dental devices, after having passed through the straw filter. Forty percent of tested units contained >500 CFU/mL in the flushed water sample. The guideline of flushing decreased contamination to acceptable levels. Studies are being conducted using polymerase chain reaction and pathogen-specific primers to determine if residual biofilm in bottle reservoirs may increase the risk of transmission of human pathogens.
Conclusions: Together, these data show that each established guidelines is effective at reducing overall bacterial contamination, resulting in water of appropriate microbiologic quality reaching the patient.