Remineralization Effects of Zinc-Containing Glass Ionomer Cement Restoratives on Demineralized Enamel Under pH Cycling Conditions

(1) Background: White spot lesions (WSLs) on enamel result from demineralization and are an early sign of dental caries. Glass ionomer cement (GIC) has been widely used for its remineralization potential, and zinc-containing GIC (zGIC) has been introduced to enhance this effect. However, its efficacy compared to conventional GIC (cGIC) remains unclear. This study aimed to evaluate and compare the remineralization effects of cGIC and zGIC on WSLs. (2) Methods: Thirty-six bovine enamel specimens were prepared, demineralized for four days, and divided into three groups: control, cGIC, and zGIC. Half of each specimen’s treated window was covered with varnish, and a two-week pH cycling protocol was conducted. Mineral density (MD) changes were assessed using microcomputed tomography (Micro-CT) at five time points: pre-demineralization, after demineralization, immediately after treatment, and 1- and 2-weeks post-treatment. Scanning electron microscopy (SEM) was also performed. (3) Results: MD values in the zGIC and cGIC groups were significantly higher than in the control group throughout every post-treatment assessment (p < 0.05). zGIC demonstrated significantly higher MD than cGIC (p < 0.05), and SEM images revealed inferior mineral deposition. (4) Conclusions: These findings suggest that zGIC is more effective in remineralizing WSLs than cGIC over two weeks.