The fillings of the future could be bioactive glass, according to engineers at Oregon State University.

The futuristic-sounding bioactive glass is a crushed glass containing compounds such as silicon oxide, calcium oxide and phosphorus oxide. It has already been used for decades in some types of bone healing, however bioactive glass is new in the world of dentistry. Researchers believe that when used in composite tooth fillings it could prevent bacteria from attacking the filling, helping them to last longer.

This could be important news for the future of dental fillings, as more than 122 million composite tooth restorations are made in the United States alone every year.

To test the idea, the team used recently extracted human molars to make samples that simulated the human mouth. Composite fillings containing 15% bioactive glass were placed in some samples, and non-bioactive composite fillings were placed in others. Microscopic gaps were allowed to form around the fillings, before tooth-decaying bacteria were added.

The results showed that in the samples with bioactive glass fillings, there was a significant reduction (61%) in bacterial penetration into the gaps, reducing their ability to attack the fillings. In the other samples however, with no bioactive glass, there was 100% penetration.

Commenting on the results, Jamie Kruzic, a professor and expert in advanced structural and biomaterials in the OSU College of Engineering said, "The bacteria in the mouth that help cause cavities don't seem to like this type of glass and are less likely to colonize on fillings that incorporate it. This could have a significant impact on the future of dentistry."

Bioactive glass has this antimicrobial effect partly thanks to ions such as calcium and phosphate, which have a toxic effect on bacteria.

As well as slowing tooth decay, bioactive glass could also provide some minerals that could help replace those being lost said the researchers, making an even longer lasting tooth filling.

If the findings by Kruzic and his team can be confirmed by clinical research, Kruzic believes bioactive glass could be easily incorporated into existing formulations for composite tooth fillings to help prevent decay and promote dental health.

The research was published in the journal Dental Materials, and supported by the National Institutes of Health.