Abstract: Background Nigella Sativa or Habbatul Baraka is an important medical plant that has been studied by researchers especially in last decades due to its beneficial medical effects, it has the ability to improve general health, additionally, it has a role in improving oral health through its inorganic and organic constituents and through its antibacterial (ant cariogenic effect). This study was conducted to investigate the effect of Nigella Sativa aqueous extract on microhardness of initial enamel caries (remineralizing effect) in companion with that of sodium fluoride. Materials and methods Fifty maxillary human permanent premolar teeth were used in this study, twenty five teeth were used for pilot study in which the concentration of the dissolved calcium ions was measured and in order to select the concentrations of water extract of Nigella Sativa that used for microhardness test, in pilot study, the teeth were treated with agents (aqueous Nigella Sativa extract and 0.5 sodium fluoride) for two minutes for twenty days the deionized water in this study used as a control negative, then after etching with 2NHCl solution, calcium ions were measured and the concentrations of aqueous Nigella Sativa extract were selected for subsequent microhardness test, the rest number of teeth (25 teeth) were subjected to the pH cycling procedure. The teeth were immerged in twenty ml of the selected agents individually for about four minutes and then rinsed with deionized water. The agents used were 3%, 5%, 7% aqueous Nigella Sativa extract and 0.05 sodium fluoride. The samples were subjected to microhardness test using vicker's microhardness device before, after the pH cycling and after placing in the selected agents. Results It was found that the Nigella Sativa aqueous extract and sodium fluoride had the ability to increase the microhardness value of demineralized enamel. Statistically, highly significant difference (P > 0.01) was found between 7% Nigella Sativa water extract and 0.05% sodium fluoride, also highly significant difference was found between 7% Nigella extract, 0.05 sodium fluoride and deionized water, while statistical significant difference (P < 0.05) between 3% and 5% of the aqueous extract was recorded. Conclusion The water extract of Nigella Sativa at a concentration of 7% was very effective in initial enamel caries remineralization.
Keywords: Nigella Sativa, Habbatul Baraka, Microhardness, Calcium ion