A Calcium Chloride Gel as a Chemocatalytic Surface Treatment for Conventional Glass Ionomer Cement: Effects on Water Sorption and Solubility

Abstract Objectives This in vitro study aimed to evaluate a newly formulated calcium chloride (CaCl₂) gel as a chemocatalytic surface treatment for conventional glass ionomer cement (GIC) and to compare its effect on water sorption and solubility with that of a CaCl₂ solution and of radiant heat treatment using LED and Plasma Arc light curing units. Methods Fifty GIC specimens (GC Fuji IX GP® FAST) were fabricated using a split Teflon mold (6 mm diameter, 2 mm thickness) and randomly assigned to five groups (n = 10): Group 1 (Control, no treatment); Group 2 (LED, 1000 mW/cm², 40 s); Group 3 (CaCl₂ solution, 42.7 wt%, 2 min); Group 4 (CaCl₂ gel, 2 min); and Group 5 (Plasma Arc, 1975–2320 mW/cm², 10 s). Water sorption (WSP) and solubility (WSL) were assessed at baseline (24-h immersion in distilled water) and after a 14-day pH cycling protocol in 5% acetic acid (pH 3.0). Statistical analysis used the Kruskal–Wallis test with Steel–Dwass pairwise comparisons and Wilcoxon signed-rank test (α = 0.05). Results At baseline, all four treatments produced significantly lower WSL than the control group, whereas WSP was significantly reduced by CaCl₂ gel, CaCl₂ solution and Plasma Arc but not by LED. Plasma Arc produced the lowest WSP values at baseline (25.4 ± 17.7 µg/mm³) and after pH cycling (25.7 ± 17.4 µg/mm³), significantly lower than all other groups. CaCl₂ gel and solution did not differ significantly from each other in WSP or WSL at either time point. After pH cycling, the control group showed significant increases in WSP (p = 0.005) and WSL (p < 0.001), and the CaCl₂ solution group showed a significant increase in WSL (p = 0.002); no significant within-group change was detected in the LED, CaCl₂ gel or Plasma Arc groups. Conclusions Within the limitations of this in vitro study, Plasma Arc irradiation and CaCl₂ surface treatment (in either solution or gel form) reduced the water sorption and solubility of the tested conventional GIC, whereas LED irradiation significantly reduced solubility but not sorption. The newly developed CaCl₂ gel performed comparably to the conventional CaCl₂ solution. Unlike the solution, it did not show a statistically significant increase in solubility after pH cycling, although the post-cycling values of the two forms did not differ significantly. The gel may therefore be a practical vehicle for CaCl₂ surface treatment, but its clinical relevance requires confirmation in further laboratory and clinical studies.