Dental Plaque Is No Match for Catalytic Nanoparticles
In a study published in Nature Communications, researchers led by Hyun (Michel) Koo, DDS, MS, PhD, professor in the University of Pennsylvania School of Dental Medicine‘s (Penn Dental) Department of Orthodontics and in the divisions of Pediatric Dentistry and Community Oral Health, in collaboration with David Cormode , PhD, of Penn’s Perelman School of Medicine and School of Engineering and Applied Science used U.S. Food and Drug Administration-approved nanoparticles to effectively disrupt biofilms and prevent tooth decay in both an experimental human-plaque-like biofilm and in an animal model that mimics early-childhood caries.
The nanoparticles break apart dental plaque through a unique pH-activated antibiofilm mechanism.
Because the caries-causing plaque is highly acidic, the new therapy is able to precisely target areas of the teeth harboring pathogenic biofilms without harming the surrounding oral tissues or microbiota. The particular iron-containing nanoparticle used in the experiments, ferumoxytol, is already FDA-approved to treat iron-deficiency, a promising indication that a topical application of the same nanoparticle, used at several-hundred-fold lower concentration, would also be safe for human use.
After testing the ferumoxytol-hydrogen peroxide combination on a tooth-enamel-like material, the team moved on to an experimental set-up that more closely replicated the conditions of the human mouth.
“We used plaque samples from caries-active subjects to reconstruct these highly pathogenic biofilms on real human tooth enamel,” says Koo. “This simulation showed that our treatment not only disrupts the biofilm but also prevents mineral destruction of the tooth’s surface. That offered very strong evidence that this could work in vivo.”
Further studies in a rodent model that closely mirrors the stages of caries development in humans showed that twice-a-day rinses of ferumoxytol and hydrogen peroxide greatly reduced the severity of caries on all of the surfaces of the teeth and also completely blocked the formation of cavities in the enamel.
As further evidence of the treatment’s targeted effect, the researchers found no significant change in the diversity of microbes in the mouth after therapy and found no signs of tissue damage.
Incorporating nanoparticles in a mouth rinse or toothpaste could be a cost-effective way to significantly improve their effectiveness, says Koo. Many of these products already contain hydrogen peroxide and would only require the addition of a small amount of relatively inexpensive nanoparticles. With evidence backing this approach in both an animal model and a human-like model of tooth decay, the research team is actively working to test its clinical efficacy.