Prions in Dentistry

[Smilemaker100]

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I recently read an interesting article on prions and their implications in infection control in the dental profession.

Presently, there is no documentation of transmission of these proteinaceous particles in dental treatment, however, a theoretical risk has been discussed. Prions are heat resistant and can survive autoclaving at high temperatures. It is still not 100 % clear how these entities are transmitted- there are some which are genetic (CDJ- Creutzfeld-Jacob's disease),acquired through cannibalism or consumption of infected animals (mad cow disease).

Other than the universal precautions, the FDI lists some other things to consider in regards to prevention of transmission of prion entities : caution with animal derived graft materials for use in oral and periodontal surgery and heterologous human graft materials. The CDC has additional precautions: for treatment of patients with CJD, it is recommended that items such as endo files, broaches and carbide burrs be discarded after use and for heat resistant dental materials- thorough cleaning and steam autoclaving at 134 degrees Celsius for 18 minutes.

I don't recollect prions being discussed at any great length while I was in dental school but I had a bit more exposure to recent research on them when I did my undergraduate degree in microbiology & immunology. Prions were only discovered in the 1990s. A lot remains unknown about these mysterious entities. What have dental students been taught,if anything, about prions at school?

Even though the prion diseases are very rare, it will be interesting to see what research reveals about them in the future.

"Prions in Dentistry-What Are They,Should We be Concerned, and What Can We Do?"
J Can Dent Assoc 2006 72 (1):53-60
http://www.cda-adc.ca/jcda/vol-72/issue-1/53.html

 

[Sprgrover]

Prions are infectious proteins that afflict CNS tissue (specifically the brain) and it is this reason that you are unlikely to encounter them in your practice (and one reason why neurosurgeons now have increased precautions and many instruments are simply discarded as prions are resistant to heat, UV, radiation, and X-rays). Keep in mind that as of 2004 there are only 140 confirmed CJD cases worldwide (and not cause a panick for you hunters, but chronic wasting disease is becoming epidemic in deer and elk populations throughout the U.S.) It's also noteworthy that prions seem to have a rather long incubation period in animals, including humans (4-7 years by some estimates), in which no symptoms are readily visible yet the CNS tissue is highly infectious. All in all, prions pose much less of a threat to you professionally - not only in how they are spread but currently the low human cases and the recent nature of their discovery - than say Hepatitis and some of the other nasty pathogens running around out there and this is probably why you have less of a focus on them in clinical protection protocols. However, if you should happen across a hapless slow moving, wobbly elk in the toolies, it's best that you reign in your early-man instincts and don't make a meal out of him.

 

[Smilemaker100]

Prions are infectious proteins that afflict CNS tissue (specifically the brain) and it is this reason that you are unlikely to encounter them in your practice (and one reason why neurosurgeons now have increased precautions and many instruments are simply discarded as prions are resistant to heat, UV, radiation, and X-rays). Keep in mind that as of 2004 there are only 140 confirmed CJD cases worldwide (and not cause a panick for you hunters, but chronic wasting disease is becoming epidemic in deer and elk populations throughout the U.S.) It's also noteworthy that prions seem to have a rather long incubation period in animals, including humans (4-7 years by some estimates), in which no symptoms are readily visible yet the CNS tissue is highly infectious. All in all, prions pose much less of a threat to you professionally - not only in how they are spread but currently the low human cases and the recent nature of their discovery - than say Hepatitis and some of the other nasty pathogens running around out there and this is probably why you have less of a focus on them in clinical protection protocols. However, if you should happen across a hapless slow moving, wobbly elk in the toolies, it's best that you reign in your early-man instincts and don't make a meal out of him.

Sure, that is all true, however, we are not 100% informed about their biochemistry etc. If there was no significance, why would an article pertaining to the subject even be considered for publication? I thought it was an interesting subject to discuss.

 

[OrinScrivello]

CJD has been shown to be infectious via tonsil tissue as well. That's a little closer to the dental realm, I'd say.

 

[v&andy_yankee]

^what Sprgrover said.

Just a few corrections/questions though:

I think the actual number of people attributed to some form of the disease is higher. It was first discovered back in the 1950s in a cannibalistic tribe by some scientist in New Guinea, and I'm sure a good number of tribes people have been dying since then, as well as the few cases attributed to mad cow. Incubation time in humans has been set at around 15 years, but it really depends on the prion type (obviously, for sheep and cows the incubation time is a lot shorter).

Also, studies have also indicated that prions aren't necessarily solely contained to the neurons of the CNS--prions have also been found in various immunological cells such as the lymphocytes in tonsils.


To the OP,
We may not know the intricate details of how prions work, but we do know the basics, at least enough to get us by. And the basics is that it's NOT a big threat (at least not yet) and definitely not a threat to dentists, something we should be worrying about. Even if it does reside in tonsil tissue, it still seems virtually impossible to spread from host to host unless if you swap brain tissue. The biggest threat it does pose is to the agricultural community, the farmers who raise beef. Back in the 1980s, there was a huge BSE (mad cow) breakout that was quickly dealt with. People thought the nightmare was over...until 1996 when a good number of people dropped dead. And like all diseases, it's really just a game of understanding the mechanisms of how it works before we can start dealing/targeting it--right now, scientists/engineers are still befuddled as to exactly how they can cause the initial "infection" in the host and start replicating.