Effect of zinc-releasing glass ionomer cement on preventing dentin demineralization

A novel glass ionomer cement (GIC) containing BioUnion™ fillers, was developed to enhance anti-demineralization and remineralization by releasing Zn²⁺, F⁻, and Ca²⁺ ions. This study evaluated its effectiveness in preventing root dentin demineralization during pH cycling.

Bovine root dentin specimens were divided into three groups: Control (without GIC), Conventional GIC (GIC; Fuji IX, GC Corporation, Tokyo), and GIC with BioUnion™ fillers (GIC-Bio; Caredyne Restore, GC Corporation). A 4-week pH-cycling protocol was applied, involving daily exposure to a demineralizing solution (pH 4.5) for 4 h and a simulated body fluid (pH 7.4) for 20 h. Demineralization was assessed using swept-source optical coherence tomography (SS-OCT) and transverse microradiography (TMR). The characteristics of the dentin surface after the pH cycling were evaluated using the Vickers micro-hardness test and Fourier-transform infrared spectroscopy (FTIR). Data were analyzed using one-way ANOVA for FTIR and two-way ANOVA for TMR and micro-hardness.

TMR analysis revealed significantly lower mineral loss and lesion depth in the GIC-Bio group throughout the experimental period (p < 0.001), while SS-OCT images indicated intact surfaces near the margins for both GIC-Bio and conventional GIC, while the control group displayed a pronounced demineralized zone. Progressive increase on surface hardness and mineral content was observed in the GIC-Bio group as confirmed by micro-hardness testing and FTIR analysis, respectively.

GIC containing BioUnion™ fillers achieved maximal reduction in lesion depth and promoted remineralization of root dentin among the tested groups.

GIC containing BioUnion™ fillers represent a potentially viable material for the caries management due to its ability to enhance dentin remineralization and surface mechanical properties through sustained ion release during pH cycling.