Bioactive glass fillings to prolong tooth life

Bioactive glass can be used in tooth fillings to reduce the ability of bacteria to attack composite tooth fillings, and perhaps even provide some of the minerals needed to replace those lost to tooth decay, engineers from Oregon State University said.

Some studies suggest the average lifetime of a posterior dental composite is only six years.

"Bioactive glass, which is a type of crushed glass that is able to interact with the body, has been used in some types of bone healing for decades," said lead researcher professor Jamie Kruzic.

"This type of glass is only beginning to see use in dentistry, and our research shows it may be very promising for tooth fillings," he said.

"The bacteria in the mouth that cause cavities are less likely to colonize on fillings that incorporate it," he added.

Bioactive glass is made with compounds such as silicon oxide, calcium oxide and phosphorus oxide, and looks like powdered glass.

It's called "bioactive" because the body notices it is there and can react to it, as opposed to other biomedical products that are inert.

Bioactive glass is very hard and stiff, and it can replace some of the inert glass fillers that are currently mixed with polymers to make modern composite tooth fillings.

"Almost all fillings will eventually fail. New tooth decay often begins at the interface of a filling and the tooth, and is called secondary tooth decay. The tooth is literally being eroded and demineralised at that interface," Kruzic explained.

Bioactive glass may help prolong the life of fillings, researchers said, because the new study showed that the depth of bacterial penetration into the interface with bioactive glass-containing fillings was significantly smaller than for composites lacking the glass.

Fillings made with bioactive glass should slow secondary tooth decay, and also provide some minerals that could help replace those being lost, researchers said.

The combination of these two forces should result in a tooth filling that works just as well, but lasts longer.

The findings were published in the journal Dental Materials.