Statement of problem: failure of any restorative system is most frequently caused by caries; it would be advantageous if the restoration possessed antibacterial properties.
Objective: The purpose of this study was to assess the inhibitory activity of three different glass ionomer restorative systems against streptococcus mutans using the agar diffusion test.
Material and methods: The antibacterial activity of three types of glass ionomer restorations (Ketac Fil Plus;3M, Ketac Silver Aplicap; 3M, Chemfil rock; Dentsply) were evaluated against Streptococcus mutans using the agar inhibition test. Zone of inhibition on Mitis salivarius agar plates was measured after 24 hours, 48 hours and one week. Data were explored for normality using Kolmogorov-Smirnov test of normality. And one way analysis of variance (ANOVA) test was used to compare between groups. This was followed by Tukey post hoc test for multiple pairwise comparisons.
Results: At 24 hours Statistically significant largest zone of inhibition was observed with Ketac fil plus with no statistically significant difference between Ketac silver and Chemfil rock whereas at 48 hours and one week no statistically significant difference among all the tested groups.
Conclusions: Within the limits of this in-vitro study it can be concluded that conventional GIC had antibacterial effect against the streptococcus mutans better than silver zinc reinforced types of GICs especially within the first 24 hours. Also addition of new elements as silver or zinc for GICs affect negatively on their anti-bacterial role as it increase their strength and hardness with decreasing solubility so limited leach out of ions from restorations.