from the Economist:
(in a root canal) "... it is common for some of the bacteria to survive it and therefore for infections to re-emerge...(my aside) 'Much'.
The surviving bacteria are often gathered in the form of what is known as a biofilm. Bacteria in such a film are embedded in a polymer matrix, which makes them harder to kill than isolated individuals. High temps can destroy biofilms, as can chemicals, but neither is safe to use inside... a human tooth. However Chunqi Jiang, a physicist at the USC, and her colleagues have come up with a possible alternative: a dental plasma torch.
...Dr Jiang reckoned that a cold plasma, particularly one rich in oxygen ions (which are notoriously destructive of organic materials), would be enough to do the job of breaking up a biofilm without harming the patient.
I'm praying this isn't the same kind: Here's a youtube video of one cutting a motorcycle outline in less than 30 seconds... out of quarter-inch steel plate.
I like my dentist, but wouldn't trust him with this!