Dental Water Sprays Contain
Bacteria That Could Kill
Some Patients
It isn't just the dental drill you should be worried about
Oral water sprays used by dentists contain levels of some bacteria that could kill vulnerable patients, government researchers have discovered.
They found that levels of opportunistic pathogens exceeded EU drinking water safety limits in 52 out of 55 water samples taken from 21 dental surgeries in the south-west of England.
This means people with weakened immune systems, such as cancer patients and those with HIV infection, are at risk, the researchers warn. James Walker of the Centre for Applied Microbiology and Research at Porton Down and his team found several types of opportunistic pathogens in many of the dental unit water lines (DUWs) tested, including species of Mycobacterium and Legionella--both of which can cause life-threatening pneumonia.
David Turner of the British Dental Association (BDA) admitted to New Scientist: "People with compromised immune systems should worry."
The researchers also isolated oral streptoccoci in 10 per cent of the samples. Since the bacteria is only found in the mouth, it is most likely that during dental procedures it was sucked back into the tools and into the DUW. Robert Staat of the University of Louisville's school of dentistry has also found oral streptococci in DUWs. "This is like sharing spit," he says.
Normally, most of the bacteria breed- ing in DUWs occur naturally in the environment and pose little threat to most people. Even so, healthy patients shouldn't be exposed to these levels of bacteria when they are at a healthcare facility, argues Hugh Pennington, a microbiologist at the University of Aberdeen. "I wouldn't want to have these in my mouth.
Walker's team found levels of bacteria between 5 and 1200 times higher than the permitted 2500 microbes per teaspoon of water. Some of the highest bacterial counts came from DUWs that were either supplied with bottled water or were recently sanitised. This casts doubt on the effectiveness of recommendations by the BDA and its US counterpart, the American Dental Association (ADA) that surgeries should use bottled water and disinfectants to reduce the risk from bacteria.
The ADA told New Scientist that similar studies carried out in several US cities revealed bacterial counts that surpass its own safety guidelines.
Dentists in both the US and Britain are advised to use sterile water for immune compromised patients and those receiving surgery where the gum line is cut. But both the ADA and BDA admit it's not clear how strictly this advice is followed.
Despite the millions of people who visit a dentist each year, contaminated dental water was blamed for only a handful of infections. Although some patients died, the link to dental water was never proved.
Source: Applied and Environmental Microbiology (vol 66, p 6636)

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