Preventing Oral Dual Biofilm Development with Innovative Bioactive Varnishes

This study introduces innovative varnishes incorporating natural bioactive compounds to inhibit the formation of oral dual biofilms, a critical contributor to dental caries and other oral diseases. The purpose of this study was to evaluate the effectiveness of bioactive varnishes containing <i>tt</i>-farnesol, quercetin, and theobromine in inhibiting the formation of mixed <i>Streptococcus mutans</i> and <i>Candida albicans</i> biofilms. Mixed biofilms of <i>Streptococcus mutans</i> UA159 and <i>Candida albicans</i> SC5314 were grown in 96-well plates containing a specialized culture medium. Approximately 0.2 mL of experimental varnishes with A-1.5% or B-4.5% concentrations of <i>tt</i>-farnesol, quercetin, and theobromine were separately added to the wells using a disposable applicator, with a vehicle varnish (lacking bioactives) serving as the control. Biofilms were incubated at 37 °C with 5% CO₂ for 24 h. Microbial viability was determined in terms of colony-forming units per milliliter (CFU/mL), and biofilm morphology was evaluated qualitatively via scanning electron microscopy (SEM). Statistical analyses were performed using ANOVA/Tukey tests at a 5% significance level. Varnishes A and B achieved significant reductions in microbial populations within the biofilms (<i>p</i> < 0.05) compared to the vehicle control (C). SEM imaging revealed marked structural disruptions in the biofilms, validating the quantitative results. Higher bioactive concentrations demonstrated enhanced inhibitory effects. Bioactive varnishes enriched with theobromine, quercetin, and <i>tt</i>-farnesol represent a novel and effective strategy for inhibiting oral dual biofilm development, offering a promising advancement in preventive dentistry.