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When patients go to the dentist to fill a cavity, they’re trying to solve a problem – not create a new one. But many dental patients get bad news: Bacteria can dig under their tooth-coloured fillings and cause new cavities, called recurrent caries. 

Now, a collaboration between researchers in the University of Toronto's department of materials science & engineering, Faculty of Dentistry, and the Institute of Biomaterials and Biomedical Engineering (IBBME) has resulted in a novel way to minimize recurrent caries.

, Assistant Professor Ben Hatton of the Faculty of Applied Science & Engineering, Associate Professor Yoav Finer of the Faculty of Dentistry and PhD candidate Cameron Stewart of IBBME tackled the issue and proposed a novel solution: a filling material with tiny particles made by self-assembly of antimicrobial drugs, designed to stop bacteria in its tracks.

These particles may solve one of the biggest problems with antibacterial filling materials: How do you store enough drug within the material to be effective for someone’s entire life?

“Adding particles packed with antimicrobial drugs to a filling creates a line of defence against cavity-causing bacteria,” says Hatton. “But traditionally there’s only been enough drug to last a few weeks. Through this research we discovered a combination of drugs and silica glass that organize themselves on a molecule-by-molecule basis to maximize drug density, with enough supply to last years.”

This discovery of using antimicrobials that self-assemble means the team can pack 50 times as much of the bacteria-fighting drugs into the particles.

“We know very well that bacteria specifically attack the margins between fillings and the remaining tooth to create cavities,” says Finer. “Giving these materials an antimicrobial supply that will last for years could greatly reduce this problem.”

Looking ahead, the research team plans on testing these new drug-storing particles in dental fillings, monitoring their performance when attacked by bacteria and saliva in the complex environment inside their mouths.

Hatton says the researchers are still far from testing on patients, but the Faculty of Dentistry “has a well-established program for the development and testing of dental materials and procedures. The immediate next steps after in vitro material testing will be to test cavities in an animal model to prove safety and efficacy.”
 
The research was funded by the National Institutes of Health, Canadian Institutes of Health Research, Canada Foundation for Innovation: John R. Evans Leaders Fund and the Ministry of Research and Innovation Ontario Research Fund.