Research progress and antibacterial mechanisms of plant essential oils as alternative therapies for periodontitis

Periodontitis is a chronic inflammatory disease caused by subgingival plaque microorganisms, and its treatment is often limited by the antibiotic resistance of conventional drugs. Plant essential oils, owing to their wide availability, relatively high safety, and multi-target antibacterial properties, have emerged as potential alternative or adjunctive therapies for periodontitis. This review systematically summarizes recent research on the antibacterial activity and mechanisms of plant essential oils against the microbial complexes of subgingival plaque (red, orange, yellow, green, purple, and blue complexes). Findings indicate that various essential oils exhibit significant inhibitory effects against key pathogens (e.g., P. gingivalis , T. forsythia , F. nucleatum ), with minimum inhibitory concentration values often below 100 μg/mL. Some essential oils effectively inhibit biofilm formation at sub-inhibitory concentrations. The primary mechanisms include disruption of bacterial cell membranes, interference with metabolic pathways, downregulation of virulence gene expression, and inhibition of quorum sensing systems. Specific individual components (e.g., carvacrol, thymol, eugenol, cinnamaldehyde, thymoquinone, and methyleugenol) demonstrate multi-target antibacterial properties, providing a basis for developing standardized oral care products. The application of delivery systems (e.g., nanoemulsions, liposomes) can enhance the stability and bioavailability of essential oils while preserving or augmenting their antibacterial activity. Despite their promising antibacterial potential, the practical application of plant essential oils is still constrained by issues such as low water solubility, residual toxicity, and chemical instability. Therefore, future efforts should focus on optimizing delivery systems and systematically evaluating their toxicological profiles. This review aims to provide a theoretical foundation for developing novel essential oil-based antibacterial agents against periodontitis and to offer new strategies for addressing the challenge of antibiotic resistance.