Antibacterial effect of different concentrations of garlic (Allium sativum) extract on dental plaque bacteria

Background: Allium sativum, commonly known as garlic, exhibits antibacterial effects against a wide range of bacteria. Aim: The objective of this in vitro study was to assess the antibacterial effect of different concentrations of garlic extract against human dental plaque microbiota. Materials and Methods: Antibacterial activities of four different concentrations of garlic extract (5%, 10%, 20%, and 100%) were evaluated against Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius, Pseudomonas aeruginosa, and lactobacillus spp. using the disk diffusion method. Papers soaked in 0.2% concentration chlorhexidine gluconate and saline were used as positive and negative controls, respectively. The data were subjected to one-way ANOVA and the Tukey multiple comparisons test at a 5% significance level. Results: All bacterial strains were inhibited by all test materials. The inhibition zones of the different concentrations of garlic extract were not significantly different for S. mutans, S. sanguis, and S. salivarius. For P. aeruginosa and lactobacillus spp. the inhibition zones of 5%, 10% and 20% concentrations were not significantly different from one another, but they were significantly more than that of the 100% extract. Conclusion: The 5%, 10%, 20%, and 100% concentrations of garlic extract had similar effects, so further studies seem to be indicated on the usefulness of the 5% extract.