Implications of Biofilms in Dental Unit Waterlines
My ultrasonic line recently tested positive for bacteria. Can you advise on how best to ensure the safety of the water in this instrument?
1 Answers
Maintaining safe dental unit waterlines (DUWL) for all items connected to air or waterlines (handpieces, ultrasonics, and air/water syringes) is critical to ensuring patient and practitioner safety. The United States Environmental Protection Agency (EPA) sets standards for safe drinking water at ≤ 500 colony forming units (CFU)/mL.1 The US Centers for Disease Control and Prevention (CDC) Guidelines for Infection Control in Dental Health-Care Settings—2003 state that bacterial counts in DUWLs for nonsurgical procedures should be "as low as reasonably achievable" and must minimally meet the EPA drinking water standard of ≤ 500 CFU/mL.1
To ensure DUWLs meet EPA standards,1,2 the Organization for Safety, Asepsis, and Prevention (OSAP)2and the CDC2 recommend the following:
- Consult with your dental unit manufacturer for directions on DUWL products and protocols and to ensure proper maintenance scheduling.1
- Use commercially available devices, products, and procedures, including self-contained water reservoirs designed to isolate water from municipal supplies; chemical treatments intended to inactivate biofilms; cartridges designed to kill bacteria and prevent biofilm attachment; in-line microfilters; or a combination of these.1
- Utilize safe source water (≤ 500 CFU/mL), including, tap, distilled, or sterile water.1
- Self-contained water reservoirs must be maintained according to manufacturer instructions or they will rapidly become contaminated. Self-contained water alone will not eradicate biofilm formation, so controlling the quality via devices, products, or procedures is necessary.1
- Flush all DUWLs for 20 seconds to 30 seconds between patients to remove any possible contaminants from the previous patient. Most dental units are equipped with anti-retraction valves to prevent "suck-back" of contaminated fluid.1 Even with these valves, flushing for 20 seconds to 30 seconds is still recommended.1 There is no longer a need to flush DUWLs for 1 minute to 2 minutes at the beginning of the day, as evidence suggests that firmly adherent biofilms are not dislodged by flushing alone. As such, flushing for 20 seconds to 30 seconds is adequate to clear stagnant lines.1Flushing alone, however, does not qualify as good quality control.1
References
- Kohn WG, Collins AS, Cleveland JL, et al. Guidelines for infection control in dental health-care settings—2003. MMWR Recomm Rep. 2003;52:1–61.
- From Policies to Practice: OSAP's Guide to the Guidelines: Workbook. Annapolis, Maryland: Organization for Safety, Asepsis and Prevention; 2004.
- Organization for Safety Asepsis and Prevention: Dental Unit Waterlines Q & A. Available at: osap.org/?page=issues_duwl_1. Accessed February 26, 2017.
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