Dental Unit Waterline Disinfection Demo

2. Dental Unit Water line disinfection
Can contaminated dental unit waterline transmit disease?
Yes, there have been documented cases of disease transmission from dental unit waterlines. In 2011, an 82-year-old woman in Italy was diagnosed with legionellosis and died 2 days later. The patient’s only known risk of exposure for Legionella infection were two dental appointments. Molecular testing was able to identify the dental unit waterlines as the source of the bacteria. Most recently, in 2015 (Georgia/Southern California) , an outbreak of Mycobacterium abscessus odontogenic infections was reported in children receiving pulpotomy treatment from a pediatric dental clinic. The suspected source of the Mycobacterium was contaminated water from dental unit waterlines. What is Biofilm? Biofilm is a thin, slimy film of bacteria that sticks to moist surfaces, such as those inside dental unit waterlines. Biofilm occurs in dental unit waterlines because of the long, small-diameter tubing and low flow rates used in dentistry, the frequent periods of stagnation, and the potential for retraction of oral fluids. A few disease-causing microorganisms found in untreated dental unit water include Legionella, Pseudomonas aeruginosa, and nontuberculous Mycobacterium.
What can be done to ensure dental unit water quality?
Dental health care personnel should use water that meets environmental protection agency regulatory standards for drinking water (i.e., ≤500 colony forming units (CFU)/mL of heterotrophic water bacteria) for non-surgical dental treatment output water. Self-contained water systems (e.g., independent water reservoir) combined with chemical treatment (e.g., periodic or continuous chemical germicide treatment protocols). For surgical procedures, sterile saline or sterile water should be used as a coolant/irrigant. Conventional dental units cannot reliably deliver sterile water even when equipped with independent water reservoirs containing sterile water because the water-bearing pathway cannot be reliably sterilized.
Monitoring methods: Dental procedural water monitoring can be accomplished using water-testing laboratory services or in-office chairside kits. Laboratory testing: When using a laboratory testing service, users should request that water be tested using the most current version of the spread plate R2A agar method (9215C) or membrane filtration method (9215D) from Standard Methods for the Evaluation of Water and Wastewater published by the American Water Works Association (AWWA) or the most current equivalent method. Tests should be conducted for longer incubation times at lower recommended temperature to allow growth of slow-growing water bacteria.
Why NaOCl is not recommende to use in DUWLs Disinfection?
Very corrosive and damaging to the dental unit water system. (Plamondon TJ, Mills SE, Sherman LR, Nemeth J, Puttaiah R. Effect of bleach on mature biofilm in dental unit waterlines. J Dent Res 1996;75:414.) High amounts of trihalomethanes (carcinogens) are produced when in contact with organic matter such as biofilms. (Puttaiah R, Siebert J, Chen P. Release of disinfection-byproducts during NaOCl use on contaminated dental unit water systems. Annual Meeting of the Organization for Safety and Asepsis Procedures Providence, RI, abstract #9807; June 18-21, 1998.)
Constantly present low levels of NaOCl in the presence of organic matter can also increase the total trihalomethane levels beyond levels set by the U.S. Environmental Protection Agency. The use of NaOCl for the specified purpose of cleaning DUWLs has not been approved by the U.S. FDA.