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The importance of water quality in Dentistry

Water quality, within Dentistry, is an extremely important element that needs to be maintained to reduce any potential pathogen risk. Water is used within Instrument cleaning, washer disinfector fill, ultrasonic fill, manual cleaning sink fill, rinsing, DUWL’s, autoclaves and drinking and can sometimes be overlooked regarding the necessity to maintain.

There are many different types of pathogens that are associated with water, with the primary ones being Legionella and Pseudomonas. All Dental practices should have a copy of the L8 ACOP document which describes the management of water supplies to control legionella and have an up-to-date legionella risk assessment.

UK infection control guidance documents outline ‘The quality of DUWL output water, entering the patient’s mouth, is limited by the input water quality’. What can affect this quality, and ultimately harbour harmful bacteria, is biofilm that can form within the DUWL tube line. Biofilms are found in many different types of systems and are very tenacious and difficult to remove with conventional cleaners or biocides.

Biofilms form when individual bacteria, in a water line, adhere to the tube surface. When many bacteria adhere, a mechanism called quorum sensing changes the way that the adhered bacteria behave. The adhered bacteria then secrete a protective polysaccharide slime, forming a continuous film. Biofilms start to grow within slow moving or stagnant water, hence the importance of trying to keep the water moving as much as possible.

The European standard for drinking water states that the output water must not exceed 100 Colony Forming Units (CFU) of bacteria per ml of water. This is deemed as good, safe, quality water. I think that it is reasonable to say that the water entering into a patient’s mouth should, at least, be in line with this European standard. UK Dentistry guidance states that to meet the microbiological quality for output water, the input water must be below 200 CFU/ml. To help control this water should be stored for the shortest possible time, before use, and storage containers should be regularly disinfected to control biofilm.

We should also be flushing the DUWL’s for 2 minutes at the start and end of the day and after any prolonged period of down time. In addition, we should also be flushing for 20-30 seconds in between patients. This process will not stop the growth of biofilm; however, it will dramatically slow the growth process down by breaking the quorum sensing cycle. It is also important that we introduce a biofilm remover to the system overnight or at weekends.

To ensure that we have good quality water and no significant biofilm issue, I would also recommend the use of a microbiological dip slide be carried out every 3 months. This will help to provide us with the safe knowledge that we have any biofilm issues under control.

Which ever product you chose to use to control Biofilm and keep the systems pathogen free, you shou

ld always follow the manufacturers guidance on the use and application. There are also several specific legionella filtration units, that can be retrofitted to taps and treatment centres, that you may also find useful in ensuring maximum safety.

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