November 3, 2022

Biofilm in dental waterlines: Addressing the CDC health alert

Dental unit waterline sample vials being held by a laboratory technicians

This article will be updated with the latest news on the progression of the CDC’s Health Advisory regarding biofilm in dental waterlines. This post was last updated on December 20, 2022.

On October 31, 2022, the Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory urging dental practices to prioritize dental waterline maintenance. The alert states that the CDC was notified in March 2022 of a new cluster of suspected nontuberculous Mycobacteria (NTM) infections in children following dental procedures at a pediatric dental clinic which is currently being investigated. 

NBC News reported that, “NTM can cause serious infections in the lungs, skin, lymph nodes or blood” and “is found naturally in soil, dust and water, but in some moist environments, the microorganisms can clump together and stick to surfaces, forming biofilms that are difficult to eliminate.” 

The growth of biofilm is a known challenge for dental professionals as “dental waterlines are at a particularly high risk […] because of their ‘long, small-bore tubing and low flow rates used in dentistry and the frequent periods of stagnation.’” Once a biofilm is formed, it can house harmful bacteria like NTMs that would likely result in infection if used on open tissue. The CDC shared that the waterline tests from the initial site visit of the suspected infection showed microbial counts much higher than the level recommended by the EPA (less than or equal to 500 CFU/mL).

Has biofilm in dental waterlines led to infection before?

This case echoes the tragedies that occurred during the 2016 contamination at a pediatric clinic in Anaheim, California and 2015 in Atlanta, Georgia which both impacted children ranging from 4-8 years. The Anaheim dental waterline contamination led to the exposure of at least 500 pediatric patients to potential infection, 221 ongoing lawsuits, and 71 confirmed NTM infections following pulpotomy procedures. And the outbreak in Georgia resulted in 24 cases of mycobacterium abscessus infections in children receiving pulpotomy treatment. In both cases, preliminary tests verified that the offices had “not [used] disinfectants in their dental unit waterlines or regularly [monitored] water quality” (CDC HAN, 2022).

As a heartbreaking result of the contaminated waterlines in both Anaheim and Georgia, “children developed severe infections with clinical diagnoses such as cervical lymphadenitis and mandibular or maxillary osteomyelitis, and required hospitalization, treatments such as intravenous antibiotics, and surgical procedures. Complications from their infections included permanent tooth loss, hearing loss, facial nerve palsy, and incision fibrosis” (CDC HAN, 2022).

As Karen Daw, MBA, CECM, CDICP said of the Health Advisory, “It’s unfortunate that this has happened yet again. Children, some requiring hospitalization and surgery over something preventable, serve as a reminder of the importance of following CDC recommendations. That is, treat waterlines regularly with disinfectants and monitor/test them to ensure they meet EPA standards for safe drinking water. Accomplishing this is now easier than ever with in-office water disinfectants and testing kits. If a practice is unsure of how to go about this, consultants and continuing education courses are available to assist. Nobody should ever feel like they need to ‘know it all’ when it comes to safety.”

What can I do to stop dental waterline infections?

The sad truth is that outbreaks like these are 100% avoidable. Unfortunately, maintaining dental waterlines often falls down (or off) on the list of priorities for dental offices. Dentistry as a whole needs to place greater importance on waterline maintenance. Like Shannon Mills, DDS said, “We now know that there are health effects associated with water that does not meet guidelines when used in certain procedures. It is time for dentistry as a profession to take this seriously.”

The best weapon we have is to educate ourselves. As the AAPD states, “Knowledge of current best practices in infection control can help reduce exposure to and contamination risks from infectious materials.” We believe it’s essential for any dental staff member to understand not only the need to prioritize waterline maintenance in every dental office, but also how to maintain and monitor dental waterlines. 

Here are three things you can do now for dental waterline infection prevention in your practice:

1. Understand Waterline Maintenance Standards

It’s important to know what each group recommends or requires to ensure that your practice is following their guidelines carefully. Note that even if your Dental State Board does not have a formal regulation regarding dental waterline maintenance, they are obliged to follow the CDC recommendations as a part of “providing ordinary and reasonable care in a prudent and competent manner to be practicing within the standard of care” (Graskemper, 2004). The CDC’s publication Guidelines for Infection Control in Dental Health-Care Settings — 2003 and the CDC’s Summary of Infection Prevention Practices in Dental Settings: Basic Expectations for Safe Care is where you can find these recommendations discussed in detail.

2. Develop Standard Operating Procedures

SOPs should be easy to follow and effective. Within the often complex world of dentistry, this can be a tall order. We recommend working with an expert to develop an SOP that is right for your practice.

3. Actively Monitor Dental Waterline Quality

Evaluating the quality of water in your lines today is essential. Practices can monitor or test their waterlines regularly through various testing methods. While these methods may vary in form, each will show whether your waterlines are within compliant CFU counts or not. As Amanda Hill, RDH, said, “The great thing about dental unit waterline safety is there’s an easy way to test if you are compliant. And the only way to know if your protocol is keeping your patients and staff safe is to test!”

How to be CDC Compliant

The CDC has laid out the following recommendations for various parties involved in this important conversation. (For the full list of recommendations, reference the original Health Advisory).

Recommendations for Dental Providers:

  • For all oral surgical procedures, use sterile saline or sterile water as a coolant or irrigant for surgical procedures
  • For all non-surgical dental procedures, use water that meets CDC recommendations (i.e., ≤500CFU/mL of heterotrophic water bacteria).
  • Consult with the dental unit manufacturer for appropriate methods and equipment to maintain the quality of dental water. Many commercial devices and procedures are available and designed for this purpose.
  • Follow recommendations for monitoring water quality provided by the manufacturer of the unit or waterline treatment product.
  • 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.
  • Review the US Food and Drug Administration’s (FDA) website on Dental Unit Waterlines for recommendations for dental practitioners.

Recommendations for Dental Facilities:

  • Ensure that the dental facility has an infection prevention plan that includes policies and standard operating procedures dedicated to maintaining and monitoring water quality. (If you have any questions about this, feel free to contact our safe water experts. We can help you develop your process from end-to-end free of charge.)
  • Provide staff training on how to properly maintain and monitor dental water quality. 
  • Contact the manufacturer of the treatment product or device if you have questions about the instructions for use.
  • Document all maintenance records, monitoring results, and employee trainings. Records should be maintained according to state and federal requirements.
  • Report infections suspected to be associated with receiving health care, including dental care, to the appropriate public health authorities. Here is the CDC provided contact information for State Healthcare Associated Infections (HAI) Prevention Programs.

For additional information, you can check out the ADA and FDA’s safe water recommendations.

Where do I begin?

If this is your first (or even the most jarring) exposure to dental waterline infection, it can be very overwhelming. Initially, we want to encourage you to take a step back and remember that while these cases are indeed terrible, they do not have to be the outcome for patients going forward. We have the technology, knowledge, and expertise in the world that can mitigate the risk of infection from dental waterline contamination.

We would love to help you find your footing within waterline maintenance. Our team is here to help you build a simple, repeatable, and documented protocol, backed by 100,000s of testing data. Simply schedule time with one of our safe water experts here.


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Publish Date:

November 3, 2022


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