Prolonging the life of composite tooth fillings could be an important step forward for dental treatment, the researchers say, since more than 122 million composite tooth restorations are made in the United States every year. 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.
The new research was published in the journal Dental Materials.
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.
Bioactive glass may help prolong the life of fillings, researchers say, 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 say. 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. Oregon State University has developed a laboratory that's one of the first in the world to test simulated tooth fillings in conditions that mimic the mouth.
If this laboratory result is confirmed by clinical research, it should be very easy to incorporate bioactive glass into existing formulations for composite tooth fillings, author said.
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 neutralize the local acidic environment.