Caries bacterium may contribute to composite degradation

Secondary caries is one of the major reasons for dental resin composite replacement. Now, a study has provided new evidence that Streptococcus mutans, an oral bacterium that causes tooth decay, compromises the resin–dentin interface and thus contributes to dental resin composite and adhesive degradation.

In collaboration with the University of Toronto's Institute of Biomaterials and Biomedical Engineering, researchers at the university's Dental Research Institute studied standardized specimens of resin composite, and total-etch and self-etch adhesives that were incubated with S. mutans for 30 days.

Electron microscopy scans of the specimens' surfaces after the period found that all materials incubated with S. mutans showed increased degradation compared with controls. In addition, a trend of increasing bishydroxy-propoxy-phenyl-propane release, a Bis-GMA-derived biodegradation byproduct, throughout the incubation period was observed for all materials and this was more elevated in the resin composite and self-etch adhesive specimens in the presence of the bacteria.

The study, titled "Cariogenic Bacteria Degrade Dental Resin Composites and Adhesives," was published online on Sept. 11 in the Journal of Dental Research ahead of print.