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Abstract: Objective: The recovery of mutans streptococci in saliva and dental biofilm samples depends, in part, on the culture medium used. In this study, we compared (i) the culture media Sucrose-Bacitracin agar (SB-20), Modified SB-20 (SB-20M) and Mitis Salivarius Bacitracin agar (MSB) in the count of colony forming units (cfu) of mutans streptococci and (ii) in the morphological and biochemical differentiation between Streptococcus mutans and Streptococcus sobrinus. Design: Samples of non-stimulated saliva from 20 children were plated on SB-20, SB-20M and MSB, and incubated in microaerophilia at 37°C for 72h. Identification of microorganisms was based on analysis of colony morphology under stereomicroscopy. The biochemical identification of colonies was done by biochemical tests using sugar fermentation, resistance to bacitracin and hydrogen peroxide production. Results: There was no significant difference (p >0.05) in the number of cfu of mutans streptococci recovered on SB-20 and SB-20M agar. Comparing the media, SB-20 and SB-20M yielded a larger number of mutans streptococci colonies (p <0.05) and were more effective than MSB in the identification of S. sobrinus (p <0.05), but not of S. mutans (p >0.05). Conclusion: There was no significant difference between SB-20 and SB-20M culture media in the count of mutans streptococci, demonstrating that the replacement of sucrose by coarse granular cane sugar did not alter the efficacy of the medium. Compared with MSB, SB-20 and SB-20M allowed counting a larger number of mutans streptococci colonies and a more effective morphological identification of S. sobrinus. [Copyright &y& Elsevier]

• Dental caries is still one of the most prevalent diseases in children worldwide. • The effect of green tea and its extract, EGCG, as mouthwashes in children at high caries risk and prevalence was studied. • Rinsing with EGCG solution effectively reduces the levels of mutans streptococci and lactobacilli in the oral cavity of children. • Both EGCG and green tea could be used as alternatives to chlorhexidine-based mouthwashes. • The reduction of mutans streptococci was higher than lactobacilli. This study was conducted to evaluate and compare the antimicrobial efficacy of green tea and its extract epigallocatechin-3-gallate (EGCG) as a mouthwash in children. The study group included 47 children aged 5-12 years at high caries risk and prevalence. Children selected were asked to rinse with one of the substances (EGCG, green tea, chlorhexidine and distilled water) for one min. A non-stimulated salivary sample (2 mL) was collected at baseline and after rinsing. The concentration of cariogenic microorganisms (mutans streptococci and lactobacilli) was determined before and after rinsing based on the count of colony-forming units (CFU). CFU were counted with the aid of a stereomicroscope through the perfunctory identification of the morphological characteristics of CFU. The microbial reduction percentage was then calculated. The analysis of the effectiveness of the treatments showed that there was a significant reduction in relation to the values obtained before and after the mouthwash, both for mutans streptococci (pCHX = 0.001; pEGCG = 0.001; pGreen Tea = 0.005; pDistilled Water = 0.018) and lactobacilli (pCHX = 0.001; pEGCG = 0.002; pGreen Tea = 0.008; pDistilled Water = 0.033). The percentage of microbial reduction of both cariogenic microorganisms caused by the EGCG solution was higher than green tea and distilled water, but less than CHX. The percentage of microbial reduction by the EGCG solution for mutans streptococci was 79.9%, green tea 68.3%, distilled water 50.6% and CHX 95.5%. For lactobacilli, the percentage reduction of all solutions was relatively lower when compared to mutans streptococci. For the EGCG solution it was 72.09%, followed by green tea 59.17% and distilled water 41.96%, but less than CHX 86.02%. Rinsing with EGCG solution reduced the levels of mutans streptococci and lactobacilli in the oral cavity of children. Although EGCG had better antimicrobial activity than green tea, this study supports the effectiveness of both as an antibacterial mouthwash option. Both EGCG and green tea could be used as alternatives to chlorhexidine-based mouthwashes. [ABSTRACT FROM AUTHOR]