Dentists complete 122 million composite tooth restorations in the United States each year, according to Oregon State University (OSU). But the average lifetime of posterior dental composites is only 6 years. Bioactive glass may improve their durability and provide some of the minerals that have been lost to tooth decay.
“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. The hard and stiff material can replace the inert glass fillers now mixed with polymers to make modern composite tooth fillings.
“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 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 is made with compounds such as silicon oxide, calcium oxide, and phosphorous oxide, and it looks like powdered glass. Its antimicrobial effect 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 neutralize the local acidic environment.
“Almost all fillings will eventually fail,” Kruzic said. “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 demineralized at that surface.”
Researchers say bioglass may help prolong the life of fillings because the depth of bacterial penetration into the interface with bioactive glass-containing fillings was significantly smaller than for composites lacking the glass. These fillings should slow secondary tooth decay and replace lost minerals to work just as well as other fillings while lasting longer.
The research used recently extracted human molars to produce simulated tooth restoration samples. If clinical research confirms its results, incorporating bioactive glass into existing formulations for composite tooth fillings should be very easy, Kruzic said.
“My collaborators and I have already shown in previous studies that composites containing up to 15% bioactive glass, by weight, can have mechanical properties comparable or superior to commercial composites now being used,” said Kruzic.
The study, “Bioactive Glass Fillers Reduce Bacterial Penetration Into Marginal Gaps for Composite Restorations,” was published in Dental Materials and supported by the National Institutes of Health.