The Inhibitory Effects of Green Tea (camellia Sinensis) on the Growth and Proliferation of Oral Bacteria

Camellia sinensis, commonly known as green tea, has been shown to possess antimicrobial properties and to lower the risk of cardiovascular disease and periodontal diseases. This study investigates the effects of brewing green tea at varying concentrations and durations on its antimicrobial activity against common oral bacteria, such as Streptococcus mutans, Porphyromonas gingivalis, and Staphylococcus epidermis. Gram stain tests revealed that our bacteria cultures had a mixture of Gram-positive and Gram-negative bacteria. A paper disk diffusion test revealed that increasing the concentration of green tea and decreasing brewing time increased the zones of inhibition; the tea brewed at a concentration of 80 mg/mL for 20 minutes had the greatest antibacterial effect. In the mouthwash paper disk diffusion test, a new bottle of Scope® was found to be most effective against common oral bacteria, while Listerine® was found to have little effect. The minimum inhibitory concentration test implied a positive correlation between the concentration of green tea and bacterial growth. Tests indicated that Scope® had a considerable effect against bacterial growth, green tea had minimal effect, and water had no effect; however, these results were inconclusive due to small sample size. As confirmed by the study, green tea does have antibacterial properties, but further investigations are required to make a definitive conclusion.