New Dental Unit Waterline Guidance from the FDA

New Dental Unit Waterline Guidance from the FDA

Dental Unit waterlines, which are narrow tubes that connect water to dental instruments (e.g. air/water syringe, dental handpiece, ultrasonic scaler), have long been a topic of discussion and concern.  The formation of biofilm is not uncommon in dental unit waterlines due to the presence of long narrow-bore tubing, inconsistent flow rates, and the potential for retraction of oral fluids.  Biofilms are a colony of  microorganisms (e.g. bacteria, fungi, or a mixture of organisms), organic, and inorganic material that stick to a surface, such as living tissue, indwelling medical devices, or plastic.

 The organisms in the biofilm work together and help to protect each other. The organisms on the outer part of the biofilm may be killed by disinfectant, but the organisms further inside the biofilm will continue to survive.  Dental unit waterlines, just by their very nature, are perfect environments for the formation of biofilm.

Healthcare-associated infections related to dental unit waterlines have occurred in the recent past. A 2015 outbreak in Georgia in which 20 children that had undergone a pulpotomy (baby root canal) developed an infection with Mycobacterium abscessus, a rapidly growing multi-drug resistant non-tuberculous type of Mycobacterium.  

This organism is found everywhere in the environment in water, dust, and soil. All of the children involved in the Georgia outbreak required hospitalization with 17 patients requiring surgical excision and 10 receiving outpatient intravenous antibiotics.  The source of the infection was traced to dental unit waterlines at the pediatric dental practice.  The Centers for Disease Control and Prevention investigation concluded:

“This outbreak was caused by contaminated water used during pulpotomies, which introduced M. abscessus into the chamber of the tooth during irrigation and drilling.”

A 2016 outbreak of Mycobacterium abscessus (M. abscessus) among children that received pulpotomies at an oral surgery clinic in California brought this issue to the forefront once again.  This outbreak, which affected 73 children, was similarly traced to improper disinfection of dental unit waterlines as well as not using sterile water for irrigation in surgical procedures.

The cost to the pediatric dental patients that acquired this infection was pretty severe: hospitalization, surgical removal of the infection, including removal of the jawbone in some cases, and prolonged antibiotic treatment.  Some patients may have lasting dental problems because of this healthcare-associated infection.

The Food and Drug Administration (FDA) recently published new guidance for dental unit waterlines, which mirrors the Centers for Disease Control and Prevention (CDC) and the American Dental Association (ADA) recommendations. The three organizations concur with the following practices:

  • Dental unit waterlines should be regularly disinfected to meet drinking water standards.  Check the unit manufacturer’s instructions (e.g. owner’s manual) for appropriate disinfectant and frequency.
  • Monitor the dental unit waterlines to ensure the water meets drinking water standards (<500 CFU/mL of heterotrophic water bacteria).  Check with the unit manufacturer’s instructions, the disinfectant manufacturer’s instructions and/or the Dental Board to determine frequency of monitoring. In-office monitoring kits are available as are kits from commercial water testing laboratories.  When using any water quality testing kit, follow the instructions precisely being sure not to inadvertently contaminate the testing materials since this will affect culture results.
  • Develop policies for disinfecting and testing dental unit waterlines.
  • Ensure all staff that are responsible for disinfecting the lines and/or testing water quality have been trained and can demonstrate competency.
  • Discharge water and air for a minimum of 20 – 30 seconds after each patient, from any device connected to the dental water system that enters the patient’s mouth (e.g., handpieces, ultrasonic scalers, and air/water syringes). Flushing after every patient is recommended even with antiretraction valves.
  • For units using separate water reservoirs, purge the dental unit waterlines each night and whenever units are out of service to prevent stagnant water from settling within the waterlines.
  • Follow the dental unit manufacturer’s instructions for replacement or other actions to repair lines that are visibly contaminated or damaged as well as all periodic maintenance instructions.
  • The FDA recommends remaining alert to musty odors, clogged lines, cloudy or particulates in the water as signs of biofilm formation and to take appropriate action based on the unit and/or disinfectant manufacturer’s instructions.
  • For surgical procedures such as biopsy, periodontal surgery, apical surgery, implant surgery, and surgical extractions of teeth:
    • Use sterile water or sterile saline for irrigation or cooling
    • Use sterile delivery systems that are disposable (e.g. bulb syringes) or that can be sterilized after each patient.

The highlights of the FDA, CDC, and ADA recommendations have been discussed along with the rationale for the importance of proper care of dental units and dental unit waterlines.  For help with dental infection control concerns, contact Infection Control Results for assistance to keep your patients and staff safe. Services offered include an on-site assessment and education.

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