Antibacterial effects of light-cured liners.

Light-cured liners and glass ionomers have recently been introduced and it has not been established if they are antimicrobial. This study determined the effectiveness of several light-cured liners against Streptococcus mutans #6715. Fluoride release and pH determination tests were performed to define their antibacterial activity. After evaluation with agar diffusion methodology, two of the light-cured glass ionomers were considered inhibitory. These two liners released fluoride into the agar in excess of the minimum inhibitory value of 20 ppm. The other four materials released fluoride below reported inhibitory values, failed to lower the pH below 4.0 and were ineffective against Streptococcus mutans. The findings suggested that light-cured glass ionomers react similarly to conventionally-cured glass ionomers regarding antibacterial activity against Streptococcus mutans. It also indicated that antibacterial activity was dependent upon a lower pH. Fluoride release may not be as important to the mechanism of action; however, it cannot be ruled out.