Rosemarinus officinalis and Thymus eriocalyx essential oils combat in vitro and in vivo dental biofilm formation

The antimicrobial activities of Rosemarinus officinalis and Thymus eriocalyx essential oils and chlorhexidine were assessed against Streptococcus mutans and Streptococcus pyogenes in particular against a biofilm growth. The oils were analyzed by GC and GC–MS and their antimicrobial activities and biofilm formation preventive properties were studied in vitro and invivo. Male and female volunteers brushed with essential oil blended toothpastes were studied for prevention of dental plaque. Twenty and eighteen compounds were identified in the essential oils of R. officinalis and T.eriocalyx respectively. Minimal bactericidal concentrations (MBC) of the R. officinalis and T.eriocalyx oils were found to be 2000 and 4000 ppm and those of chlorhexidine (0.2%) were 8000 and 1000 ppm for both S.mutans and S.pyogenes respectively. Decimal reduction time of S.mutans by R. officinalis and T.eriocalyx oils at their MBC levels was 2.8 minutes. D value of S.pyogenes exposed to R. officinalis and T.eriocalyx oils and to chlorhexidine were 4.28, 3.6 and 2.8 minutes respectively. Antibacterial and in vivo biofilm preventive efficacies of all the concentrations of rosemary oil were significantly (p<0.001) higher. Our results show effective doses of 2 and 8 mg/ml for R. officinalis and T.eriocalyx oils in planktonic cultures. In vivo experiments indicated that lower concentrations of the oils, in particular the rosemary oil, were high significantly (p<0.001) effective during the course of the study as compared to chlorhexidine. In conclusion there may be a potential role for essential oils in the development of novel anticaries treatments.