Comparison of the antibacterial effect of 0.2% chlorhexidine and apple extract on decreasing salivary Streptococcus mutans counts

The most common cause of dental caries is the Streptococcus mutans. Control of dental caries with the use of mouthwashes has been introduced for many years. The aim of this research was to make a comparison between the antibacterial effects of chlorhexidine and Nigella sativa extract as a natural mouthwash. In this in vitro study، salivary samples of 20 subjects were transferred onto a solid culture. Then 10 subjects، as group 1، used chlorhexidine and the remaining 10، as group 2، used apple extract. The salivary samples of both groups were again transferred onto the solid culture. The number of grown colonies in each group before and after the use of mouthwashes were counted and compared. Data were analyzed with t-test using SPSS 17 (α=0. 05). The results did not show a significant difference between the colony counts before the use of mouthwashes; but the average number of colonies after interference in group 1، (p value < 0. 001) and in group 2 (p value < 0. 002) significantly decreased. The decrease in colony counts of group 1 was significantly more than that of group 2 (p value < 0. 001). The bacterial reduction percentages after interference with chlorhexidine and Nigella sativa extract were 92. 8% and 54. 5%، respectively. Nigella sativa extract can be used as an antibacterial substance for the oral cavity; however، chlorhexidine is still considered a standard and more effective mouthwash.