<![CDATA[ABSTRACTBackground: Streptococcus sp colonies are Gram-positive coccus bacteria that play a role in the formation of dental plaque and cause dental caries. However, dental caries can be prevented with the gold standard mouthwash, namely chlorhexidine. In other studies, many mouthwashes have been developed using traditional ingredients that have antibacterial potential, one of which is hibiscus flower (Hibiscus rosa sinensis L.). This is due to the presence of chemical compounds that can inhibit the growth of Streptococcus sp in dental plaque.Objectives: Testing the effectiveness of 0.2% chlorhexidine and H. rosa sinensis L. extract against Streptococcus sp in dental plaque.Method: Laboratory experimental research with pre and post test only control group design on 6 groups. Group K- (aquades), K+ (chlorhexidine), H. rosa sinensis L. extract 6.25% (P1), 12.5% (P2), 25% (P3), 40% (P4). Each of these groups consisted of 4 subjects. Data were obtained by counting the number of Streptococcus sp colonies before and after gargling which had been streak-cultured on blood agar media. The statistical analysis used the Shapiro Wilk test showed significant results P ≥ 0.05, followed by the One Way ANOVA parametric test. While the not significant results with the Kruskall Wallis non-parametric test.Results: There was a significant difference between the 4 concentrations of H. rosa sinensis L. extract 6.25% (P1), 12.5% (P2), 25% (P3), and 40% (P4) with the control (+) (p = 0 .00), and at a concentration of 25% (P3) effectively inhibited the growth of Streptococcus sp bacteria by 12.5%.Conclusion: H. rosa sinensis L. extract was effective compared to 0.2% chlorhexidine in inhibiting the growth of Streptococcus sp. Administration of various concentrations of H. rosa sinensis L. mouthwash extract inhibited the growth of Streptococcus sp, and at a concentration of 25% (P3) effectively inhibited Streptococcus sp by 12.5%.]]>
