Anti-microbial activity of Green Tea Extracts and Nicotine on the Growth, Biofilm Formation of Salivary Mutans Streptococci (In-vitro study)

Background: The green tea have antimicrobial activity against many types of bacteria It is considered a natural substance with few side effect.         Aim of the Study: An in vitro study was carried out to investigate the ability of green tea extract and nicotine to inhibit growth, biofilm formation by salivary Mutans streptococci. Methods: This study included a convenient sample of 40 healthy Iraqi volunteers aged 18–23 years old from College of Dentistry / University of Baghdad. Green tea and nicotine aqueous extract were prepared in different concentration to use in agar diffusion method to detect the activity of extract, and ELISA reader in multi titer plate was used to determine the ability of salivary mutans Streptococci to form biofilm in the presence and absence of the extracts.to measure the biofilm inhibition rate.         Results: Mutans Streptococci were sensitive to green tea and nicotine in different concentrations     the diameters of the inhibition zone were effective in a dose dependent manner significantly. There was a significant difference between the concentrations of each extracts, antibacterial activity was in a dose dependent manner for the extracts. The minimum bactericidal concentration of green tea was (280 mg/ml) and minimum bactericidal concentration of nicotine was (45mg/ml). The study found that biofilm formation by Mutans Streptococci was markedly decreased in the presence of 1/2 minimum bactericidal concentration of both green tea and nicotine with mean of O.D 590 nm = 0.54 in comparison with green tea extracts and nicotine alone O.D 590 nm = 0.15, 0.68 respectively. Conclusions green tea and nicotine extracts in different concentration effectively reduced the biofilm formation of salivary Mutans streptococci. While the presence of nicotine has negatively impacted on the ability of green tea extracts in the inhibition of biofilm formation by Mutans Streptococci in vitro.