Managing dental unit waterlines


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managing dental unit waterlines
Photo: Olga David Tadevosian 123RF

Smarter management of dental unit waterlines is essential for the safety of dental patients and staff—and it could just save your practice. By Cameron Cooper

To say that clean dental unit waterlines are crucial to the health of a practice—for patients, staff and the bottom line—is an understatement.

As dentists operate in an environment of heightened infection-control risks because of COVID-19, the spotlight is on the dangers of waterline contamination from biofilm—a layer of microorganisms such as bacteria and fungi that forms in wet places. The upshot of poor processes can be the transmission of diseases such as legionella, Pontiac fever and the coronavirus.

Emeritus Professor Laurence Walsh, of the UQ Oral Health Centre at The University of Queensland School of Dentistry, is a renowned researcher on waterlines. He says since the mid-1980s infection control in dental practices has typically focused on blood-borne viral infections and injuries involving sharps. Now, the pandemic is instead highlighting risks around what dental staff and patients may inhale from procedures that generate aerosols—both from patient-derived fluids and the fluids in waterlines and any other equipment such as a benchtop ultrasonic scaler unit. 

“What you breathe is going to be a bigger exposure route because you’re breathing all the time, whereas you might only get a sharps injury once every couple of years,” Professor Walsh says. “Of course, the level of awareness around aerosols and what you breathe has become a much bigger topic of interest because of COVID-19.”

Risk of practice shutdowns

Maintaining a low level of biofilm in waterlines can make or break a dental clinic, with stagnation of water inside the tubing of a dental chair having caused many shutdowns in the past. 

Professor Walsh says thick biofilm can block the tubing and prevent the flow of water in the dental unit. “Nothing hurts a practice more than a dental chair that doesn’t work,” he adds.

It’s important to do the right thing. Nothing is good when your dental practice is on the 6 o’clock news with a patient who has contracted legionella from your practice.

Emeritus Professor Laurence Walsh, UQ Oral Health Centre

A mistake in many practices, he says, is thinking that simply putting a treatment tablet in the waterline will definitively solve the problem. Not so. For a start, guidelines stress that such tablets should not be touched with bare hands because of the risk of infecting the water with bacteria shed from the surface of the skin. “Yet you see dental assistants using their bare hands to drop in these tablets all the time—and that can dose the water with skin bacteria,” Professor Walsh says.

Another common error is failing to regularly carry out ‘shock’ treatments of the waterlines to limit the build-up of any contamination. Such a process is designed to detach and break down the biofilm, rather than merely suppressing the growth of bacteria. Professor Walsh says if there is no flushing and no use of chemical additives, the level of bacteria will inevitably be very high and certainly above the 200 colony forming units per millilitre threshold limit that the Australian Dental Association recommends. 

Test, test, test

Magda Posch is a director of Biodegree, an Australian company that distributes infection-control chemicals for waterlines. 

A failure to frequently check the water in dental chairs is a dangerous oversight, she says, because different locations and climates mean that any chair needs to be individually measured and assessed. 

“Yes, you should follow the manuals and instructions of the companies producing the cleaning products, but you need to retest the water regularly to make sure that it’s working.”

Posch believes Australia is playing catch-up with markets such as Europe on the waterline-infection threat, but she is pleased the issue is now firmly on the national agenda. At a time when there is confusion about the use of products to sterilise and kill COVID-19, Posch says education and training will be crucial to inform better guidelines on appropriate disinfectant applications for waterlines.

In Australia, Biodegree distributes the products of Alpro, a German chemical company that is regarded as one of the world leaders in infection control. Its chemicals aid water decontamination and the removal of biofilm in waterlines and are biodegradable. “None of our products are harming public water systems or aqua-life. That’s a big thing because some products contain toxic components that accumulate in the ocean and kill fish.”

You’ll get the best results with waterlines when you use products that are specifically designed to work in dental equipment.

Magda Posch, director, Biodegree

She adds that dental practices should be wary of using disinfectants that are not fit for purpose, such as ordinary domestic bleach. “You’ll get the best results with waterlines when you use products that are specifically designed to work in dental equipment.” 

Professor Walsh says in addressing infection risks it is critical, for extended periods of non-use, to either remove water from the waterlines or ensure that any remaining water cannot support the growth of microorganisms (through the use of long-acting antimicrobial agents).

“Such a hibernation solution needs to be flushed thoroughly from the waterlines afterwards,” he says.

Do your homework

As waterline management comes under further scrutiny, Posch says dental practice managers need to understand the specific requirements of their dental chairs and any chemicals they are using to negate biofilm as there are significant differences between chairs manufactured in the US and Europe, the two main sources of chairs. Closely following the instructions of product labels is also important. 

“Follow the recommendations of the manufacturer, but remember to be cautious and check out marketing claims,” she says. “Some companies over-promise and under-deliver.”

Professor Walsh agrees that proper infection control requires diligence and consistent routines from dental practice staff in the way they decontaminate waterlines.

“Practices that follow manufacturers’ instructions around shock treatments get exceptionally low levels of recoverable microorganisms in their waterlines,” he says. “It’s important to do the right thing. Nothing is good when your dental practice is on the 6 o’clock news with a patient who has contracted legionella from your practice.”  


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