The Effect of Essential Oils and Bioactive Fractions on Streptococcus mutans and Candida albicans Biofilms: A Confocal Analysis

The essential oils (EO) and bioactive fractions (BF) fromAloysia gratissima, Baccharis dracunculifolia, Coriandrum sativum, Cyperus articulatus,andLippia sidoideswere proven to have strong antimicrobial activity on planktonic microorganisms; however, little is known about their effects on the morphology or viability of oral biofilms. Previously, we determined the EO/fractions with the best antimicrobial activity againstStreptococcus mutansandCandidaspp. In this report, we used a confocal analysis to investigate the effect of these EO and BF on the morphology ofS. mutansbiofilms (thickness, biovolume, and architecture) and on the metabolic viability ofC. albicansbiofilms. The analysis of intact treatedS. mutansbiofilms showed no statistical difference for thickness in all groups compared to the control. However, a significant reduction in the biovolume of extracellular polysaccharides and bacteria was observed forA. gratissimaandL. sidoidesgroups, indicating that these BF disrupt biofilm integrity and may have created porosity in the biofilm. This phenomenon could potentially result in a weakened structure and affect biofilm dynamics. Finally,C. sativumEO drastically affectedC. albicansviability when compared to the control. These results highlight the promising antimicrobial activity of these plant species and support future translational research on the treatment of dental caries and oral candidiasis.