In vitro anticariogenic and antibiofilm activities of toothpastes formulated with essential oils

Abstract Objective This study aimed to assess the antibacterial and antibiofilm effects of essential oils and herbal toothpastes against bacteria associated with oral diseases. Methods The minimum inhibitory concentration (MIC) and antibiofilm activity of 13 essential oils against Staphylococcus aureus, Streptococcus mutans, Lactobacillus lactis, and Enterococcus faecalis. were determined. Toothpastes were formulated with different concentrations of the most active essential oils, alone and in combination, and evaluated for antibacterial and antibiofilm activities. Results Clove, oregano, thyme, and cinnamon essential oils were effective in inhibiting all bacterial strains. The antibacterial activity of cinnamon essential oil was similar to that of the control (0.12 % chlorhexidine gluconate mouthwash). Cinnamon essential oil was a strong inhibitor of S. mutans growth. The antibiofilm activity of clove, oregano, thyme, and cinnamon essential oils at 1, 2, and 4 × MIC against S. mutans did not differ from that of the control. In the hole-plate diffusion assay, 17 out of the 18 tested toothpastes produced an inhibition halo at least half as large as that of the control. Toothpastes containing clove, clove and oregano, or clove, oregano, thyme, and cinnamon essential oils were able to completely disrupt S. mutans biofilms, not differing from the control. Thyme essential oil was found to act synergistically with chlorhexidine against S. mutans. Conclusions The results indicate that clove, oregano, thyme, and cinnamon essential oils may be added to fluoride-free toothpastes to enhance inhibitory effects against bacteria associated with cavities and periodontal disease. Thyme essential oil may increase the efficiency of chlorhexidine-containing dentifrices.