HARTFORD, Conn. -- The way we use fluoride hasn't changed much since the mid 20th century, but a new Yale University study could change that.
The study, led by Ronald Breaker, a professor in the department of molecular, cellular and developmental biology at Yale, gets at the specifics of how bacteria fight fluoride. Besides uncovering one of the remaining mysteries of the element -- the 13th most common in the Earth's crust -- it potentially could lead to new uses for fluoride. The study was published Thursday in the journal Science Express.
Streptococcus mutans is the bacterium particularly responsible for tooth decay. Fluoride binds to the teeth's enamel to shield against bacteria. But some researchers believe that fluoride also inhibits the growth of the Streptococcus bacterium.
Since the 1940s, when municipal governments began fluoridating public water, debates have raged over the health benefits of fluoride. The controversy has subsided since the days when some called it a Communist plot, but it hasn't gone away altogether. Breaker said his study won't likely help either side of the debate, as it looks solely at how fluoride works on a molecular level.
Breaker's study finds that bacteria's defense against fluoride is triggered by certain sections of RNA messages known as riboswitches that act as fluoride sensors. When fluoride builds up in a bacterial cell, the riboswitches trigger genes in the bacteria that produce more copies of the bacterial enzymes. It also triggers a gene that specifically expels fluoride from the cell. Knowing this, Breaker said, could lead to innovations that inhibit the anti-fluoride mechanisms.
"We want to try to identify compounds that will efficiently block fluoride channels; we want to preventively block this exporter," he said.
Fluoride is a common element and can be toxic at certain levels, Breaker said, so it's possible that these anti-fluoride mechanisms developed as an evolutionary adaptation.
"We're definitely eager to understand how bacteria sense and respond to fluoride," he said. "We want to manipulate the system and intentionally break the system, because we can see some interesting application."
Exactly what that application could be requires more research. Creating a "super-toothpaste" might be tricky because bacteria are good at building resistance, but it is not impossible. Any compound developed would likely lose its effectiveness over time, Breaker said, but new compounds could be developed to stay ahead of the bacteria.
It could also lead to a treatment for skin infection, since high concentrations of fluoride inhibit bacterial or fungal growth.
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