Although cavities are caused by bacteria, simply killing all of the bacteria in the mouth isn't a good idea, as some of them aid in digestion or have other beneficial effects. A nanoparticle coating, however, could someday prevent cavities without harming bacteria.
Cavities occur when harmful bacteria such as Streptococcus mutans reproduce to form biofilms (aka plaque) on the teeth – as they do so, they produce acids that dissolve tooth enamel. Previously, scientists have used substances like zinc oxide, copper oxide and silver to eradicate such microbes, but unfortunately those compounds also kill beneficial bacteria.
Instead, a University of Illinois at Chicago team recently focused on stopping the microbes from forming the biofilms, without harming them.
Led by Dr. Russell Pesavento, the researchers studied the effects of nanoparticles made of cerium oxide. While earlier studies suggested that such particles didn't prevent biofilm formation (and in some cases even promoted it), the U Illinois scientists knew that the qualities of cerium oxide nanoparticles are determined largely by the manner in which they're made – and their particles were created differently than the others, by dissolving ceric ammonium nitrate or sulfate salts in water.
In lab tests, polystyrene plates were seeded with a growth medium containing S. mutans bacteria, which were being fed the sugars that they use to build biofilms. When a solution of the new cerium oxide nanoparticles was added to those plates, production of such biofilms was reduced by 40 percent.
By contrast, the commonly-used anti-cavity agent silver nitrate had no effect on biofilm growth under the same conditions. What's more, the cerium oxide nanoparticles were shown to be less toxic to human oral cells.
Although more work still needs to be done, Pesavento ultimately hopes to combine the particles with enamel-strengthening fluoride, in a coating that dentists could paint onto patients' teeth.
More details on the research will be presented in an online meeting of the American Chemical Society, to be held this Tuesday (Aug. 18th).
Source: American Chemical Society
