Black and green tea antimicrobial effect on Mutans streptococci and Lactobacilli


Background Dental caries continues to be a major public health problem in many countries. The aetiology of dental caries is multifactorial and it is widely accepted that Mutans streptococci and Lactobacilli play major role in the formation of dental caries through adhering to the tooth surface and producing acid from dietary sucrose.Objectives Finding affordable natural product with anti-cariogenic potential will have a great impact on dental caries management worldwide. There is some published evidence supporting the antibacterial activity of green tea (GT) but studies of black tea (BT) are scanty. This preliminary study aimed to test the activity of aqueous and alcoholic extracts of BT and GT in comparison with sodium fluoride, chlorhexidine and distilled water, on clinical isolates of Mutans Streptococci (MS) and Lactobacilli (LB). Materials and Methods In the in-vitro study, MS and LB sensitivity and viable counts were tested with different concentrations of tea extracts. The minimum bactericidal concentration (MBC) of the tea extract, and the time required for killing MS and LB in the presence of tea extracts were determined. An in-vivo study of sequential saliva samples collected from 30 volunteers after rinsing with the aqueous extracts was conducted, to investigate the longevity of tea extract as an antibacterial agent in the mouth. Results MS and LB counts were reduced with tea aqueous extract progressively with time. The largest inhibition zone was produced by 50% GT aqueous extract. LB least viable count was recorded at 30% BT aqueous extract. MBC was 35%and 30% for BT and GT extracts respectively. The maximum reduction of MS and LBviable counts was at 30 and 15 minutes respectively, after rinsing with 50% GT aqueous extract. Conclusion Tea extract has the potential to reduce MS and LB viable counts, and can be incorporated in the dental products as an effective anti-cariogenicagent.