Clove oil nanoemulsion as a novel therapeutic strategy against Streptococcus mutans-induced dental caries and periodontitis.

The present study investigates clove oil nanoemulsion (CONE) as a novel therapeutic strategy against Streptococcus mutans-induced dental caries and periodontitis. CONE was formulated via ultrasonic emulsification, yielding a stable nanoemulsion with a mean droplet size of 44 ± 3.8 nm and a polydispersity index of 0.539. It exhibited potent, dose-dependent antibacterial activity with a minimum inhibitory concentration (MIC) of 0.4 mg/mL, a minimum bactericidal concentration (MBC) of 0.5 mg/mL, and a 25 mm inhibition zone at MIC in an agar diffusion assay. CONE significantly inhibited S. mutans biofilm formation by 82% and disrupted established biofilms with a 63% biomass reduction. Additionally, it was effective against co-species biofilms comprising Lactobacillus acidophilus and Candida albicans. Mechanistic studies revealed that CONE decreased extracellular polymeric substance production, reduced cell surface hydrophobicity (from 72% to 34%), and inhibited self-aggregation. It also suppressed glycolytic acid production and compromised acid tolerance. Furthermore, CONE induced oxidative stress, leading to lipid peroxidation and membrane damage, while exhibiting minimal cytotoxicity to human oral cells. It also showed enhanced antibacterial effects when combined with amoxicillin. These findings indicate that CONE is a promising alternative therapy for treating oral bacterial infections.