Crashing the Biofilm Party: Understanding the Path to Safe Dental Unit Waterlines
What’s All the Fuss About Dental Unit Waterlines?
If you’ve been in the dental space for a long time, you’ve seen a lot of change, particularly in the infection control space. I remember practicing without gloves and masks and wiping everything down with an alcohol-soaked 2X2. Nowadays, none of us would even consider skipping gloves, and we understand the need for proper disinfection and sterilization of patient care items. But what about all this dental unit dental unit waterline stuff (DUWL)?
I had been a hygienist for over 20 years before I had even heard of treating and testing waterlines. Back in 2018, I went to an annual OSHA bloodborne pathogens and infection control continuing education course, and the speaker mentioned testing and treating waterlines. I went back to my office the next day and asked if we were compliant.
I was met with blank stares. Thankfully, my dentist fully supported me in taking on the project, and by the next Friday, I was shocked and testing lines.
Why all of a sudden?
To me, it felt like this waterline thing was brand new. But in reality, G.C. Blake highlighted the likelihood of microbial contamination of DUWL all the way back in 1963. Then, in 1993, the Centers for Disease Control (CDC), followed by the American Dental Association in 1996, began looking into guidelines for DUWLs. Ultimately, in 2003, the CDC issued its Guidelines for Infection Control in Dental Healthcare Settings, recommending that all dental units produce water that meets the EPA standard for safe drinking water of less than 500 CFU/ml.1
Is all this overkill?
While I understood the research, I had been practicing for over twenty years and never made anyone sick. This sort of felt like busy work and one more thing in an already busy workday. But then I learned about some actual cases where people had, in fact, been sickened or even died as a result of contaminated DUWL. In the United States alone, there have been three high-profile cases and countless other cases that get settled quickly and quietly.
In 2015, 24 children in Jonesboro, Georgia, were infected with nontuberculous Mycobacteria (NTM) after receiving pulpotomies. Then, in 2016, it happened again to 71 children in Anaheim, California. These two cases shined a spotlight on dental infection control, particularly DUWLs. But it still felt pretty rare and kind of one-off.
Interestingly, in the Anaheim case, the symptoms showed up in 71 children over a long period of time. The first child developed swelling one day after treatment, and the 71st kid displayed symptoms 409 days after receiving their pulpotomy. 409 days? The frightening thing about these infections is they can stay dormant for so long. If the Anaheim outbreak hadn’t been so large and well investigated by public health, more than likely, no one would have linked the last child’s infection to their dental visit.
What I take from that data is all I can confidently say is I don’t know if I’ve ever made anyone sick. But with a proper protocol in place, I can ensure moving forward, my DUWL will never sicken a patient.
Georgia regulations
In 2022, the CDC issued an unprecedented Heath Alert Network2. This was the first one that focused on dentistry. It highlighted yet another case of children sickened by DUWLs and sounded the alarm for dental professionals to take this task seriously. At the time, the location wasn’t revealed, but we have learned that it was in Georgia. Thirteen children between the ages of 5-10 were infected with NTM and all required surgery. The interesting thing about this case is that it turned out the contamination came from a cracked pipe outside the dental office. A proper testing protocol would have revealed this issue, but there was none in place.
The Georgia Board of Dentistry has now added requirements for continuing education for all licensed dental professionals.
“Effective on and after January 1, 2024, two hours of the minimum requirement shall include education and training regarding infection control in the practice of [dentistry and] dental hygiene, which shall include education and training regarding dental unit waterlines.” 3
What to do?
Thankfully, achieving safe water isn’t a cumbersome process. Establishing a standard operating procedure (SOP) and educating the entire team in the necessary steps will set you up for success. Following these three simple steps will get you on the right track.
Step 1: Shock
Shocking your waterlines is using a strong disinfectant to clean out the bacteria, biofilm, and product residue that has been building up in your DUWL over time. This can be likened to non-surgical periodontal therapy from a hygienist or when the dentist removes all the decay from a tooth. The idea is to get the environment as healthy as possible before we move on to the next step.
When to shock:
- Before beginning a treatment protocol or when changing treatment products
- Shock regularly (recommended every 90 days to start) and extend if testing reveals less frequent is possible
- When your waterline test reveals a contamination of 200 CFU/mL or more.
Some shocks require the product to sit overnight but not longer than 72 hours and some are as short as ten minutes, so you must time it correctly. Read the instructions and follow them. Run the shock product into every single line that can provide water. If you miss a line, you might be providing a hiding place for the biofilm.
Step 2: Treat
Treatment products are low-level antimicrobials that slow the spread of all the microorganisms that want to grow in your DUWLs. They help to maintain the clean environment you created when you shocked, much like our patients' home care between visits–it keeps the biofilm and decay at bay. Treating your lines without first shocking is like brushing your teeth with your finger. You’ll remove a little plaque, but you're not really disrupting the biofilm.
Treatment products come in tablet, straw, or liquid form. Like the shock products, it’s important to read the instructions. The big thing to keep in mind is that these products are not a “Get Out of Jail Free” Card or a magic bullet. They simply are one part of the three-step process to safe water.
Step 3: Test
Testing is the fun part. This is how you know if all your shocking and treating efforts are working. And it’s how you prove to any inspectors that you are doing the right thing. The Organization for Sterilization and Asepis Prevention (OSAP) recommends testing monthly until you pass for two consecutive months and then moving to quarterly testing. The good news is you can do pooled sampling. This means you can collect equal amounts of water from all the lines from ONE operatory into one test vial. If you pass, the whole room passes. If you fail, you’re going to shock all the lines anyway.
Much like how you test your autoclave weekly, there are in-office and mail-in tests. In-office tests are convenient, economical, and confidential. But they are imprecise. Mail-in tests offer third-party verification and precise results. My office does a mail-in test once a year and in-office testing the other three quarters.
Getting Everyone On Board
The key to any successful protocol is consistency: do it and keep doing it. The entire team needs to understand the why and the how of DUWL maintenance, so it doesn’t just feel like busy work but an integral part of keeping the dental team and patients safe when in your office.
- Umer F, Khan M, Khan FR, Tejani K. Managing dental unit waterlines: a quality improvement programme. BMJ Open Qual. 2022 Jun;11(2):e001685. doi: 10.1136/bmjoq-2021-001685. PMID: 35667705; PMCID: PMC9171218.
- Centers for Disease Control and Prevention. (2022, October 31). Han archive - 00478. Centers for Disease Control and Prevention. Retrieved April 13, 2023, from https://emergency.cdc.gov/han/2022/han00478.asp
- Chapter 150-5 Dental Hygiene. GA. (n.d.). https://rules.sos.ga.gov/gac/150-5#:~:text=Effective%20on%20and%20after%20January,regarding%20dental%20unit%20water%20lines.
