When you get a cavity filled, you certainly don't want plaque growing on the filing – it could cause the tooth to decay all over again. That's why scientists from the University of Pennsylvania have evaluated an experimental new dental composite material that not only kills plaque-causing bacteria on contact, but that also stands up to everyday wear and tear.

First of all, there are already other antibacterial dental composites, which generally work by slowly releasing bacteria-killing compounds. Unfortunately, such compounds can be toxic to the surrounding tissue, plus they can contribute to antibacterial resistance. Additionally, their presence within the composite can compromise its mechanical strength.

The new material is made of a resin impregnated with the antibacterial agent imidazolium. That resin is non-leachable, meaning that the imidazolium is not released from it. Instead, the agent remains in the filling (or other restorative dental work), only killing microbes that actually touch it. The material also "has outstanding mechanical properties," easily standing up to activities such as biting and chewing.

In lab tests, the resin was found to be very effective at keeping bacterial biofilm (plaque) from growing on its surface. Only a negligible amount grew, and it was easily removed using very little shear force. By contrast, a control sample of a conventional dental composite accumulated much more plaque, which required over four times as much force to remove.

The study was funded by dental tech firm Dentsply Sirona, and is described in a paper that was recently published in the journal ACS Applied Materials and Interfaces.