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Should dentists worry about vCJD transmission?
Existing guidelines on treating patients with diseases such as Creutzfelt-Jakob disease (CJD) do not cover dental health in any detail. Writing in the April Journal of the Royal Society of Medicine Professor Stephen Porter of the Eastman Dental Institute at the University of London suggests "important modifications" to the current infection control procedures and calls for more research specifically to be done on infection via dental treatments.
Prions in teeth and gums?
So far there have been no proven cases of CJD developing as a result of dental treatment, but prions - the organisms causing CJD, scrapie and BSE - have been found in the nerve tissues of the face and mouth. In tests on animals, scrapie prions have been found to travel from dental pulp along the trigeminal nerve towards the brain at a rate of 1mm a day. So far, Professor Porter warns, "there is little information on the precise infectivity of prion-infected oral tissues".
Specific guidelines are needed
Professor Porter points out that the likelihood of prions being transmitted to dental health care workers is very small, but the possibility "cannot be excluded". He recommends:
When a patient is known to have prion disease:
- Instruments should always be discarded after use
Increasingly, single-use instruments will have to be used as new legislation comes into force for all patients
- Dental unit waterlines must not be used
Fluids from the mouth can be retracted into a dental waterline, where a biofilm of microorganisms can develop in as little as eight hours. So far, there is no system that can fully remove these biofilms. Bacteria and viruses such as HIV and Hepatitis B have been found to contaminate waterlines, and there is a risk that prions can also be retracted into the line from a patient's mouth. Professor Porter recommends using a coolant provided by syringe to avoid the risk of infection.
- Stand-alone suction systems must be used
The dental unit's suction system cannot be used on a patient with known CJD, since it is impossible to 'disinfect' a prion. Professor Porter's guidelines suggest using a stand-alone unit with disposable bowl which is incinerated after use.
Call for more research
There has been very little research done into prion infection and risk of infection in dental care. Professor Porter calls for more work to be done to get accurate statistics on the risk of CJD infection from gums, dental pulp and other oral tissues.
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