<![CDATA[Background: Streptococcus mutans is a major cariogenic bacterium involved in dental plaque formation and enamel demineralization. Although chlorhexidine is widely used as an antibacterial agent, its long-term use may cause adverse effects, prompting the search for natural alternatives. Tridax procumbens L. (T. procumbens) contains bioactive compounds with potential antibacterial properties. Objective: To evaluate the antibacterial activity of the ethyl acetate fraction of T. procumbens against Streptococcus mutans. Materials and Methods: An in vitro experimental study with a post-test-only control group design was conducted using six groups: ethyl acetate fractions of T. procumbens at concentrations of 2%, 4%, 6%, and 8%, a 0.2% chlorhexidine positive control, and a negative control. Each group consisted of four replicates. Antibacterial activity was evaluated using the agar disk diffusion method by measuring inhibition zone diameters. Data were analyzed using the Kruskal–Wallis test, followed by the Mann–Whitney test. Results: All tested concentrations exhibited antibacterial activity against S. mutans. The 8% ethyl acetate fraction produced the largest mean inhibition zone among the tested concentrations and showed an inhibitory effect comparable to that of 0.2% chlorhexidine. Statistical analysis revealed significant differences between treatment groups (p < 0.05). However, no significant differences were observed among the 2%, 4%, 6%, and 8% concentrations. Conclusion: The ethyl acetate fraction of T. procumbens exhibited antibacterial activity against Streptococcus mutans. The 8% concentration produced the greatest inhibitory effect, although increasing the concentration from 2% to 8% did not significantly enhance antibacterial activity. These findings indicate its potential as a natural antibacterial agent against S. mutans.]]>
