Résumé
OBJECTIVES: The purpose of this study was to evaluate the growth inhibitory effects of some vegetable oils on Streptococcus mutans (S. mutans) and Lactobacillus casei (L. casei). METHODS: Two bacterial strains and 5 kinds of test solutions (3 experimental groups: orange essential oil, olive oil, soybean oil; 1 positive control group: chlorhexidine solution; 1 negative control group: broth medium) were used in this study. S. mutans and L. casei pellets were exposed to 1 ml of one of the test solutions for 1 minute. Then, the treated bacterial cells were incubated in fresh broth medium for 0, 4, 8, 16, and 24 hours. The optical density of the broth medium was measured using an ELISA reader at 620 nm. A nonparametric Kruskal-Wallis test (with Mann-Whitney U tests) was performed to compare the change in optical density between different groups at different time points. RESULTS: Bacterial growth was significantly inhibited in all experimental groups compared to the negative control group. The growth of L. casei was less affected by experimental oils than that of S. mutans. Orange essential oil had the maximum growth inhibitory effect on S. mutans up to 8 hours, similar to that in the positive control group (P<0.01). Experimental oils had greater growth inhibitory effect on L. casei than chlorhexidine solution. CONCLUSIONS: This in vitro study confirmed the growth inhibitory effect of some vegetable oils on S. mutans and L. casei. Rising of the mouth using these vegetable oils is expected to have an anti-plaque effect, but additional clinical studies are needed to confirm this.