Anti-Caries and Anti-Inflammatory Effect of Salt in the Oral Cavity

Dental caries is a chronic, multifactorial, biofilm-mediated disease caused by the imbalance between demineralization and remineralization in the oral environment. Acidogenic microorganisms such as Streptococcus mutans, Lactobacillus spp., and Actinomyces spp. metabolize fermentable carbohydrates into organic acids, lowering local pH below the critical threshold (≈5.5). This acidic environment dissolves hydroxyapatite crystals (Ca₁₀(PO₄)₆(OH)₂), releasing Ca²⁺ and PO₄³⁻ ions from the enamel matrix. Remineralization is a complex physicochemical process in which Ca²⁺, PO₄³⁻, and F⁻ ions are redeposited in subsurface enamel under neutral or mildly alkaline conditions. Sodium chloride (NaCl) contributes to oral stability by neutralizing residual acids, regulating osmotic balance, and modulating ionic strength, indirectly reducing the metabolic activity and acidogenic potential of cariogenic microorganisms. Naturally mineralized salts enriched with Ca²⁺, Mg²⁺, and K⁺ support enamel regeneration by promoting ionic diffusion, enhancing crystal lattice reformation, and maintaining salivary electrolyte dynamics. In regions with salt fluoridation programs (e.g., Mexico, Switzerland, Tanzania), substitution of hydroxyl (OH⁻) groups in hydroxyapatite with fluoride ions forms fluorapatite (Ca₁₀(PO₄)₆F₂), a crystalline phase with enhanced acid resistance and lower solubility. Isotonic saline mouth rinses also exhibit antimicrobial and anti-inflammatory effects through osmotic plasmolysis of microbial cells, reduction of inflammatory mediators, and stabilization of the oral microbiome. These findings indicate that mineral- and fluoride-enriched salts are biocompatible, cost-effective, and accessible therapeutic agents for preventing and managing dental caries.