Antibacterial activity of dental restorative material: An in vitro study

The study evaluated the antibacterial effects of dental restorations such as nano-hybrid composite (Empress), a glass ionomer cement (GIC Gold label Type 9) and silver amalgam against Streptococcus mutans.

A modified bacterial suspension within the material assay was used to study the antibacterial effects. A volume of 20 μl of bacterial suspensions were placed in a narrow conical cavity within the materials. They were incubated for 0, 3, 6, 12, 24, and 48 h at 37°C. After the incubation period, the number of viable cells in the suspension was evaluated. In liquid culture assay, growth inhibition was measured at A600 nm up to 6 h in bacterial suspensions treated with the eluates of the restorative materials.

Kruskal-Wallis test and Mann-Whitney's test were performed to determine the significant differences between the control and restorative materials for given incubation periods at 5% level of significance (P < 0.05).

After 6 h of incubation, all restorative materials showed an inhibitory effect when compared to the controls. Silver amalgam showed the highest inhibition, followed by GIC Type 9 and composite. Silver amalgam showed marked inhibition after 2 h in comparison to the other material groups. These techniques employed to study the antibacterial effects showed that the silver amalgam had the pronounced inhibitory effect followed by GIC and composite. Further research on these aspects is necessary to determine whether the material can prevent secondary caries formation.