Aras Part Medical International Press International Journal of Medical Parasitology and Epidemiology Sciences 2766-6492 7 Suppl 1 2026 09 18 Comparative Antimicrobial Effects of Green Tea and Chlorhexidine Mouthwashes on Streptococcus mutans in Young Adults with Dental Caries: An In-Vivo Study S57 S62 10.34172/ijmpes.6287 EN Luma Jasim Witwit https://orcid.org/0000-0001-7892-632X Hanan Salman Hassan https://orcid.org/0000-0002-8483-2124 Ammar Abdul Sattar Hamza Journal Article 10.34172/ijmpes.6287 2026 03 28 2026 07 16 Introduction: Dental caries is a biofilm-mediated disease strongly associated with acidogenic bacteria, particularly Streptococcus mutans. Chlorhexidine is widely used for chemical plaque control, however, side effects limit its long-term use. Catechins like epigallocatechin gallate (EGCG) are abundant in green tea and has attention as a natural antimicrobial alternative. Methods: This in vivo comparative experimental study included 20 participants aged 22 years with dental caries recruited from the College of Dentistry, University of Babylon, Iraq. Participants were randomly allocated into two groups (n = 10 each): green tea mouthwash and 0.2% chlorhexidine mouthwash. Both groups used the assigned mouthwash twice daily for two weeks. Salivary samples were collected at baseline, after one week, and after two weeks. S. mutans was isolated on Mitis Salivarius Bacitracin agar and quantified as colony-forming units per millilitre. Data were analyzed using Shapiro-Wilk, Friedman, Durbin-Conover, and Mann-Whitney U tests. Results: Both mouthwashes produced highly significant within-group reductions in salivary S. mutans counts over time (P < 0.001). In the chlorhexidine group, mean colony counts decreased from 2546.0 at baseline to 99.2 after one week and 37.0 after two weeks. In the green tea group, counts declined from 2606.3 to 104.5 and 40.9, respectively. No significant between-group differences were observed at baseline, one week, or two weeks. Conclusion: Green tea mouthwash showed antimicrobial efficacy comparable to chlorhexidine in reducing salivary S. mutans. It may serve as a safe, natural, and cost-effective adjunct for caries prevention.