June 23, 2009 -- The world's smallest plasma torch, a device typically used to rip trash apart at extremely high temperatures, is set to make root canals faster, less painful and reduce the chance of infection.
"Our goal is to guarantee that you won't have to see a doctor for a follow-up visit," said Chunqi Jiang, a professor at University of Southern California who helped adapt plasma torches for dentistry and co-author a recent paper in the June issue of Plasma Processes and Polymers.
"One problem is that between 8 and 10 percent of patients have an infection post-operation. This is intended to eliminate the chance of an infection."
Plasma, or ionized gas, is one of the four basic states of matter, the other three being solid, liquid and gas. Contrary to what we experience on Earth, plasma is by far the most common state of matter in the universe; our sun and other stars are mostly plasma.
Stars create plasma by super-heating atoms and stripping off their electrons. On Earth humans use super-heated plasma to gassify trash, turning last night's leftovers into syn gas.
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The trick to creating plasma at room temperature is by pulsing it. A continuous stream of plasma very quickly heats up the surrounding air. Pulsing the plasma allows the tiny electrons in the plasma to heat up and move around, while keeping the much larger and heavier atom nucleus from heating up.
"If you have a piece of paper with bacteria on it and you apply cold plasma to it, the paper won't burn but the bacteria will die," said Mounir Laroussi, a professor at Old Dominion University who has studied the effect of cold plasmas for years. "Cold plasma can kill bacteria on a variety of surfaces such as teeth or skin."
When plasma is used in the mouth, the free electrons create single atoms of pure oxygen, ozone and other reactive combination of oxygen, all of which search for, and find, other atoms to bind with in the organic biofilms inside decayed teeth.
Biofilms are basically walled colonies of bacteria. In freshwater streams bioflims can be the slippery, brownish gunk on rocks. In the human body bioflims can trigger the onset of an infection and then protect the harmful bacteria from even the most powerful antibiotics.
Atom by atom, the oxygen punches holes in the cell walls and membranes of the bacteria, letting their cytoplasm ooze out and killing the bacteria.
It takes five to 10 minutes of cool, pulsed and purple plasma to clear an infected tooth of biofilms. Bleach, the conventional method for cleaning an infected tooth, takes 30 minutes. Even then, up to 10 percent of patients treated with bleach are still infected. Tests using the plasma torch on a few dozen human teeth have shown no signs of infection.
Other high-tech solutions to biofilms have existed for 10 years. Various laser systems can also clear away biofilms, but are expensive, costing up to $25,000.
If the plasma torch passes FDA clinical trials, which under ideal circumstances could happen within a year, the plasma torch could retail for as little as $1,000.
It could be even less than that, according to Laroussi, who has had a cold plasma torch costing less than $1000 since 2005, which he has used to test cold plasmas effect on teeth, skin and wound healing. The trick to FDA acceptance and commercialization is ensuring that only harmful cells are killed.
"We can kill bacteria on teeth and on wounds," said Laroussi. "But we have to ensure that we are not creating a worse problem in nearby healthy cells as well."
Initial tests have shown that surrounding healthy tissue remains intact, although more testing is needed to definitively prove this. In the meantime, the USC researchers are concentrating on getting the funding necessary to continue with their research.
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