Formulating a Novel Herbal Mouthwash (Oak Gall Mouthwash) and Evaluating Its Antibacterial and Antifungal Effects on 5 Common Oral Microorganisms

Background: Herbal mouthwashes improve oral hygiene due to antimicrobial activity and dental plaque control. Objectives: This study aims to investigate the antimicrobial effects of oak gall mouthwash (OGM) against five strains of Candida and Streptococcus. Methods: The extraction of oak gall was done by maceration method with 70% ethanol, with an aqueous base. The broth microdilution method was used to check the minimum inhibitory concentration (MIC) against Candida tropicalis, C. albicans, Streptococcus Sanguis, S. mutans, and S. salivarius. After culture, the mouthwash's minimum bactericidal concentration (MBC) was determined against the same microorganisms. Data were analyzed using Kruskal-Wallis and one-sample Wilcoxon tests. Results: Minimum inhibitory concentration values were as follows (mg/mL): C. albicans (0.390 ± 0.000), C. tropicalis (0.305 ± 0.252), S. mutans (0.388 ± 0.215), S. Sanguis (0.033 ± 0.010), and S. salivarius (0.027 ± 0.010). Minimum bactericidal concentration values were as follows (mg/mL): C. albicans (1.301 ± 0.404), C. tropicalis (0.650 ± 0.201), S. mutans (1.171 ± 0.605), S. sanguis (0.115 ± 0.061), and S. salivarius (0.115 ± 0.061). The one-sample Wilcoxon test showed that all MIC and MBC values for all 5 microorganisms were significantly greater than zero (P < 0.05). The Kruskal-Wallis test showed significant overall differences among the microorganisms in terms of their MIC (P < 0.05) and MBC (P < 0.05). The post hoc analyses showed 4 significant pairwise comparisons for MIC and 4 significant pairwise comparisons for MBC (P < 0.05). Conclusions: This study suggested that OGM is useful in inhibition of Candida and Streptococcus. Based on our data, the highest and lowest sensitivity to OGM were found on S. salivarius and C. albicans, respectively.