Composition of Different Herbal Extracts and Their Impact on Initial Bacterial Colonization on Enamel In Situ

Foods rich in polyphenols are known to promote oral health by modifying the enamel pellicle. In doing so, they reduce bacterial adhesion, biofilm maturation, and erosion. The goal of this study was to screen local herbal drugs available in Central Europe for their potential suitability as part of a diet promoting oral health by targeting the initial stages of biofilm formation. To achieve this, an in situ study was conducted to evaluate the effects of the four polyphenol-rich herbal extracts of blackcurrant leaves, oak bark, horse chestnut leaves, and sweet chestnut leaves on early bacterial adhesion and biofilm formation on tooth enamel over an 8 h period. This research aimed to identify natural remedies that could support oral hygiene by targeting the initial stages of biofilm formation. Study Design and Experimental Procedures: Aqueous extracts were prepared by ultrasonic extraction. Eight human subjects wore bovine enamel slabs intraorally for 8 h. After 1 min of pellicle formation, the subjects rinsed with 8 mL of the extracts for 10 min, followed by intraoral exposure without food. An 8 h-exposure without rinse served as the negative control; 0.2% chlorhexidine gluconate (CHX) served as the positive control. After 8 h, bacterial adhesion and biofilm matrix formation on the enamel slabs were quantified ex vivo using DAPI/Concanavalin A staining and fluorescence microscopy. The LIVE/DEAD™ BacLight™ assay was used to assess bacterial viability. Statistical analysis was performed by the Mann-Whitney U test and Kruskal-Wallis test (p < 0.05), as well as the Bonferroni-Holm correction (p < 0.01). Results and Conclusions: The screened herbal drugs did not demonstrate a statistically significant impact on the number of adherent bacteria, suggesting that their mode of action may not directly interfere with bacterial adhesion mechanisms. However, all four extracts exhibited consistent trends toward reduced glucan formation and decreased bacterial viability. The observed inhibition of glucan formation indicates that these drugs may potentially target the enzymatic pathways responsible for polysaccharide synthesis. By disrupting glucan production, the structural integrity of the biofilm matrix might be compromised, which indirectly affects bacterial survival within the biofilm environment.