Inhibition of microbial adherence and growth by various glass ionomers in vitro

This study measured the in vitro inhibition of growth and adherence of five oral bacteria by glass-ionomer materials. Disks were prepared from two cavity liners and four restorative class materials, by use of Teflon plates with circular wells, five mm wide and two mm deep. The bacterial species tested included: A. viscosus, S. mitis, S. mutans, L. casei, and S. sanguis. Growth inhibition studies were performed by the spreading of 0.1 mL of standardized inocula over agar plates produced with selective media, followed by the direct application of glass-ionomer disks onto the agar. On other plates, disks were placed onto uninoculated agars for 48 h, followed by bacterial inoculation. All agar plates were incubated under optimal growth conditions for each bacterial species. The four restorative materials were also placed aseptically into sterilized bovine incisors and placed into sucrose containing broth media, inoculated with S. mutans for three days. Adhering materials were disclosed and scored. An ion-exchange electrode was used to measure fluoride release over a seven-day period for all six glass ionomers. The two cavity liners and two of the restorative materials produced the largest growth inhibition zones by direct contact. No growth inhibition occurred when the specimens were allowed to come into contact with the agars prior to inoculation. All four restorative materials reduced bacterial accumulations on enamel surfaces by over 80%. Elevations in short-term fluoride release levels were positively correlated with growth inhibition.