'Bioactive' glass for long-lasting tooth fillings

An antibacterial 'bioactive' glass may not only prolong the life of dental fillings but also prevent secondary tooth decay and even replace some lost minerals, scientists say.
Engineers at Oregon State University (OSU) in US have made some promising findings about the ability of "bioactive" glass to help reduce the ability of bacteria to attack composite tooth fillings.
An average person uses their teeth for more than 600,000 "chews" a year, and 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 Jamie Kruzic, a professor at the OSU College of Engineering.

"This type of glass is only beginning to see use in dentistry, and our research shows it may be very promising for tooth fillings," Kruzic said.
"The bacteria in the mouth that help cause cavities don't seem to like this type of glass and are less likely to colonise on fillings that incorporate it. This could have a significant impact on the future of dentistry," he said.

Bioactive glass is made with compounds such as silicon oxide, calcium oxide and phosphorus oxide, and looks like powdered glass.
It is called "bioactive" because the body notices it is there and can react to it, as opposed to other biomedical products that are inert.

"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 said.
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.
Recently extracted human molars were used in this research to produce simulated tooth restoration samples for laboratory experiments.
The antimicrobial effect of bioactive glass is attributed, in part, to the release of ions such as those from calcium and phosphate that have a toxic effect on oral bacteria and tend to neutralise the local acidic environment.
The research was published in the journal Dental Materials.