When a dentist drills out the decayed section of a tooth that has a cavity, it’s important that they also remove the bacteria that caused the decay in the first place – or at least, that they remove as much of it as possible. If they don’t, the bacteria can get reestablished, causing the filling to fail. Now, scientists from the University of Maryland’s School of Dentistry have developed a new cavity-filling system that they say will not only kill virtually all residual bacteria, but also help the tooth to regrow some of the tissue that was lost to decay.

The system consists of a primer that is applied to the surface of the drilled-out tooth, an adhesive that is then applied to help the filling bond to the tooth, and the filling material itself. The three substances contain ammonium and silver nanoparticles, plus they have a high pH, all of which have been shown to kill bacteria.

“The reason we want to get the antibacterial agents also into primers and adhesives is that these are the first things that cover the internal surfaces of the tooth cavity and flow into tiny dental tubules inside the tooth,” said lead scientist, Prof. Huakun (Hockin) Xu.

Some people may be wary of the technology, however, as silver nanoparticles have been linked to health problems such as immune system deficiencies.

The filling material itself additionally contains calcium phosphate nanoparticles, which promote the regrowth of tooth minerals. While it isn’t clear if this could ultimately allow the tooth to completely rebuilt itself, it should at least help the drilled section to heal over. Although the longevity of fillings made with the material hasn’t yet been tested, Xu’s team believes that they should last considerably longer than traditional fillings.

So far, the primer, adhesive and filling material have been tested on biofilms made from saliva provided by volunteers. Trials utilizing the teeth of lab animals and human participants are being planned.