Antimicrobial Efficacy of Iron Oxide Nanoparticles Incorporated in Commercial Toothpaste Against Streptococcus mutans, Enterococcus faecalis, Candida albicans, and Lactobacillus

Background: Maintaining oral hygiene is Crucial for preventing dental diseases associated with microbial biofilms. Traditional toothpaste formulations have limitations in effectively combating biofilm-associated pathogens such as Streptococcus mutans, Enterococcus faecalis, Candida albicans, and Lactobacillus. Iron oxide nanoparticles have shown promise in enhancing antimicrobial efficacy due to their ability to generate reactive oxygen species (ROS) and disrupt microbial cell walls. Aim: To evaluate the antimicrobial efficacy of iron oxide-enriched toothpaste against key oral pathogens to determine its potential in improving oral health and biofilm inhibition. Materials and Methods: Iron oxide nanoparticles were synthesized and incorporated into a commercial toothpaste at varying concentrations (25 µg/mL, 50 µg/mL, and 100 µg/mL). The antimicrobial activity was avaluated using agar well diffusion, time-kill curve, and biofilm inhibition assays. The study analyzed microbial inhibition against S. mutans, E. faecalis, C. albicans, and Lactobacillus using statistical methods, including one-way ANOVA, Tukey HSD post hoc tests, independent t-tests, effect size calculations (Cohen’s d, Hedges' correction, and Glass’s delta), and multivariate analysis (Pillai’s Trace, Wilks’ Lambda, Hotelling’s Trace, and Roy’s Largest Root). Results: Iron oxide nanoparticle-enriched toothpaste demonstrated significant antimicrobial activity, with a dose-dependent reduction in microbial growth. The highest inhibition was observed for S. mutans, followed by E. faecalis, C. albicans, and Lactobacillus. The 100 µg/mL Fe₂O₃ NP formulation showed the most pronounced inhibition, significantly outperforming commercial toothpaste. Conclusion: The findings indicate that Iron oxide nanoparticle-enriched toothpaste effectively inhibits biofilm formation and microbial growth, particularly against S. mutans. This suggests its potential as an advanced oral hygiene product to combat dental caries and biofilm-associated infections. Further research is needed to assess its long-term safety and efficacy in clinical settings.