Oral bacteria are ready to spring into action the moment a dental hygienist finishes scraping plaque off a patient’s teeth. Eating sugar or other carbohydrates causes the bacteria to quickly rebuild this tough and sticky biofilm and to produce acids that corrode tooth enamel, leading to cavities. Scientists now report a treatment that could someday stop plaque and cavities from forming in the first place, using a new type of cerium nanoparticle formulation that would be applied to teeth at the dentist’s office.
Russell Pesavento, the project’s principal investigator, wanted to find something that wouldn’t indiscriminately kill bacteria in the mouth and that would help prevent tooth decay, rather than treat cavities after the fact. He and his research group turned to cerium oxide nanoparticles. Other teams had examined the effects of various types of cerium oxide nanoparticles on microbes, though only a few had looked at their effects on clinically relevant bacteria under initial biofilm formation conditions.
When the researchers seeded polystyrene plates with S. mutans in growth media and fed the bacteria sugar in the presence of the cerium oxide nanoparticle solution, they found that the formulation reduced biofilm growth by 40% compared to plates without the nanoparticles, though they weren’t able to dislodge existing biofilms. Under similar conditions, silver nitrate — a known anti-cavity agent used by dentists — showed no effect on biofilm growth. Pesavento would like to combine the nanoparticles with enamel-strengthening fluoride in a formulation that dentists could paint on a patient’s teeth.