The increasing demand for alternatives to antibiotics against resistant bacteria has led to research on natural products. Aim of this study was to analyze the antimicrobial and antibiofilm activity of 16 Mediterranean herb extracts against representative oral microorganisms. The production of ethyl acetate extracts and the assays were carried out under established experimental conditions. The extracts were analyzed using High Performance Thin Layer Chromatography (HPTLC). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts from Achillea taygetea, Cistus creticus ssp. creticus, Cistus monspeliensis, Lavandula stoechas, Mentha aquatica, Mentha longifolia, Origanum vulgare, Phlomis cretica, Rosmarinus officinalis, Salvia sclarea, Satureja parnassica, Satureja thymbra, Sideritis euboea, Sideritis syriaca, Stachys spinosa, and Thymus longicaulis were determined against eight typical oral bacteria and the fungus Candida albicans. Microtiter plate test was conducted to evaluate the antibiofilm activity against Streptococcus mutans. Overall, all tested extracts efficiently suppressed the growth of obligate anaerobic bacteria. The extracts exhibited moderate to high antibiofilm activity comparable to that of chlorhexidine (CHX) against S. mutans. Interestingly, R. officinalis and O. vulgare demonstrated the highest antibacterial activity against oral bacteria. Additionally, R. officinalis and L. stoechas significantly inhibited S. mutans biofilm formation at 0.15 mg / ml. Parvimonas micra showed high susceptibility to R. officinalis, while C. albicans was sensitive to the O. vulgare extract with a minimal fungicidal concentration (MFC) of 2.50 mg / ml. These results suggest that the investigated plant extracts can be considered as alternative natural antimicrobial and antibiofilm agents against infectious oral diseases.

Antibacterial properties of toothpastes enable chemical plaque control in limited-access tooth regions that are mechanically not sufficiently reached by toothbrushes. Therefore, this study aimed to compare different microbial methods to assess antimicrobial toothpaste properties and evaluate different toothpastes in terms of their antibacterial efficacy against different oral microorganisms in vitro. Six toothpaste suspensions with varying antibacterial supplements were applied to a multi-species biofilm model (Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans) as well as to each microorganism. A culture method was used to assess the anti-biofilm effects and two different agar diffusion assays were performed for testing the antimicrobial effect on each microorganism. The measurements of the culture and diffusion analyses were statistically normalized and compared and toothpastes were ranked according to their antimicrobial efficacy. The results of both agar diffusion assays showed a high correlation across all tested species (Spearman correlation coefficients ρs > 0.95). The results of the multi-species biofilm model, however, substantially differed in its assessment of antibacterial properties (ρs ranging from 0.22 to 0.87), compared to the results of both diffusion assays. Toothpastes with amine fluoride with and without stannous fluoride, and triclosan resulted in the highest antimicrobial efficacy, while activated carbon supplements were comparable to the negative control NaCl. The appropriate selection of a broad range of oral microorganisms seems crucial when testing the chemical impact of toothpastes and toothpaste supplements.