The effect of black seed oil extracts on mutans streptococci in comparison to chlorhexidine gluconate (in vitro)


Background: The black seed or Nigella sativa has been used for centuries to promote health and fight disease. Thisplant has a great focus for research due to its antibacterial, antifungal, anti-tumor, and hypotensive effects. Thisstudy was conducted to assess the effect of the black seed oil extract on sensitivity of mutans streptococci and theadherence to tooth surface in comparison to chlorhexidine gluconate in vitro.Materials and methods: Four different concentrations of black seed oil extract (1%, 5%, 10%, and 20%) were preparedusing ethanol as a solvent for the evaluation of the antimicrobial activity of the black seed oil extract against mutansstreptococci isolated from saliva of volunteers and compared with 0.2% chlorhexidine gluconate using agar diffusiontest, followed by determination of the Minimum Bactericidal Concentration (MBC) of the black seed oil extract.Three concentrations (1%, 5%, and 10%) were used in the adherence study whereby a stainless steel wires werethreaded from one end in the roots of previously cleaned, polished and sterilized first premolars, which were thenimmersed in 10 ml of the agent for 2 minutes, followed by washing with sterilized deionized water. The teeth werethen immersed in 10ml Brain Heart Infusion Broth and inoculated with 2% of bacterial isolates and incubatedaerobically at 370C for seven days. A positive score was given to the microbial growth on wire, teeth and bottleindicating a non-effective treatment and vice versa.Results The study showed inhibition zones for black seed oil extract which were found to be increased as theconcentration of the extract increased. The MBC of the black seed oil extract against mutans streptococci was 10%.The results also showed that the oil extract was effective in inhibiting the adherence of mutans streptococci to toothsurface at a concentration of 10%.Conclusion: The black seed oil extract has a bactericidal effect against mutans streptococci at a concentration of10%, and can inhibit the adherence of these microorganisms to tooth surface