Naringin Inhibits Bacteria, Biofilms In Vitro, Reduces Caries In Vivo

This study evaluates the anti-cariogenic potential of naringin, a flavonoid, by assessing its inhibitory effects on cariogenic bacteria growth, acid production, polysaccharide synthesis, and biofilm formation in vitro. In vitro experiments used broth microdilution to determine minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and biofilm inhibitory concentrations (MBIC50/MBRC50) of naringin against Streptococcus mutans, S. sanguis, and S. sobrinus. Live/dead staining visualized bacterial viability in biofilms, while fluorescence labeling quantified adhesion to saliva-coated hydroxyapatite. In vivo, a rat caries model assessed caries severity via salivary bacterial counts, X-ray imaging, Keyes scoring, and fluorescent staining. Systemic safety was evaluated through hematology and histopathology. Naringin inhibited planktonic bacteria (MIC 0.5–1 g/L) and biofilms (MBIC50 1–4 g/L), reduced acidogenesis (p<0.05), and suppressed water-insoluble extracellular polysaccharide (IEPS) synthesis in S. mutans and S. sanguis (p<0.05). In rats, 1–2 mg/mL naringin decreased salivary cariogens (p<0.05) and superficial dentin caries scores without systemic toxicity. Naringin demonstrates multi-targeted anti-cariogenic activity by inhibiting bacterial growth, acid production, and biofilm formation, supporting its potential as a natural therapeutic for dental caries prevention.