Antibacterial Effects of Essential Oils on Oral Pathogens

Objectives: Chlorhexidine-digluconate (CHX) is one of the most used antibacterial agents for oral disinfection and can be considered as a gold standard. There is an increasing desire for alternative products which can sufficiently be used for oral disinfection but remain save and harmless to the host cells at the same time. Essential oils are able to meet these demands. This study aimed to assess the antibacterial effects of different essential oils and compare them with CHX-containing products and over-the-counter oral hygiene products.
Methods: Inhibition zones were measured to evaluate n=32 products (n=15 essential oils, n=7 CHX-containing gels/solutions, n=10 commercially available dentifrices/mouthrinses) and their antibacterial effects on n=7 groups of oral pathogens (Streptococci, Lactobacilli, Actinomycetes, Aggregatibacter actinomycetemcomitans, Staphylococcus aureus, Candida albicans, Enterococcus faecalis). Mann-Whitney-U-test was used to compare inhibition zones (mean in mm) of different products on pathogen growth. Level of significance was set to p<0.05.
Results: Overall, highest mean inhibition zones were found in thyme-oil (37.57mm), Parodontax dentifrice (33.03mm) and AJONA dentifrice (31.50mm). CHX-solution as gold standard generated a maximum mean inhibition zone of 22.17mm. No growth inhibition zones were found in coconut-, sesame-, jojoba-, palm-, sunflower- and olive-oil. Streptococci, Actinomycetes, Aggregatibacter actinomycetemcomitans, Candida albicans and Enterococcus faecalis were most inhibited by thyme-oil (23.33-46.00mm; p<0.05). Lactobacilli were most inhibited by Parodontax dentifrice (49.83mm; p<0.05) while tea-tree-oil inhibited Staphylococcus aureus most (43.67mm; p<0.05).
Conclusions: Some essential oils like thyme-oil are able to inhibit growth of different oral pathogens. Inhibition zones of essential oils were partially more efficient than the gold standard CHX-solution.