Inorganic Ion Permeation through Human Dentinal Tubules: Implications for Bioactive Endodontic and Desensitizing Therapies

Abstract

Introduction: This study aimed to evaluate the effects of pH, molecular weight, and ion charge on the permeation efficiency of selected inorganic ions through dentinal tubules.

Methods: Standardized 0.5 mm-thick human dentin slices were prepared and exposed to various inorganic salt solutions under pH = 4, 7, and 10 conditions. Ion permeation was quantified over a 60-minute period. Morphologic changes were examined via scanning electron microscopy. ANOVA and Spearman's correlation were used to analyze the influence of multiple variables on the diffusion of ions.

Results: pH values were found to be the most influential factor: ion permeation is significantly enhanced under acidic environments and is hindered under alkaline conditions. Molecular weight and ion charge also affected diffusion, with lower molecular weight and +1 charge ions showing superior permeation. No significant difference was observed between cations and anions. Scanning electron microscopy analysis revealed no crystal deposition or tubule occlusion under the conditions investigated in this work.

Conclusions: Ion permeation through dentinal tubules is primarily governed by environmental pH, followed by ion charge and molecular weight. These findings inform the rational design of ion-releasing dental materials tailored for acidic environments. Further research should explore long-term effects and multiion interactions to enhance clinical relevance.

Keywords: Dentinal tubules; inorganic salts; ion permeation; pH-dependent diffusion.