Abstract: Objective: To study the effects of green tea, wild chrysanthemum, mint extract and their compound on the proliferation, acid production and adhesion of Streptococcus mutans. Methods: Streptococcus mutans were cultured in MS medium containing different concentrations of plant extracts for 24 h, then centrifuged and washed. The bacteria cells were suspended in a certain volume of distilled water, and the optical density was measured by spectrophotometer. The pH of the supernatant was measured using a pH meter after centrifugation. The effect of the extract on the adhesion of Streptococcus mutans was observed by slide adhesion method. Results: Each extract and its compound inhibited the proliferation, acid production and adhesion of Streptococcus mutans (P<0.05). When the concentration was 24 g/L, the effect of green tea on the proliferation of Streptococcus mutans was stronger than that of other extracts (P<0.01). When the concentration was 0.75 g /L, 1.5 g / L and 3 g / L, the inhibitory effect of the compoundon Streptococcus mutans adhesion was stronger than that of other extracts (P<0.05) . Conclusion: All the three plant extracts have a certain anti-caries ability, and showed significant synergistic antibacterial activity.

Key words: Green tea, Wild chrysanthemum, Mint , Streptococcus mutans , Cariogenicity