“Assessment of the remineralizing potential of nano-bioactive glass, nano-hydroxyapatite, and sodium fluoride on artificial carious lesions in primary teeth”

Abstract

Tooth decay represents a dynamic balance characterized by alternating cycles of demineralization and remineralization, though loss of minerals can be reversed in its early stages. Recently, nanomaterials have been widely explored in dentistry due to their remarkable characteristics and enhanced remineralization potential. This study aimed to assess the remineralization performance of three varnishes on artificial enamel lesions in primary teeth: commercial fluoride varnish (5% NaF + ACP), experimental nano-bioactive glass (6% n-BAG), and experimental nano-hydroxyapatite (10% n-HAP). The twenty-eight extracted primary molars were randomly divided into four groups: Group 1 (Enamel Pro), Group 2 (n-BAG), Group 3 (n-HAP), and Group 4 (control). Specimens were submerged in a demineralization medium for 96 h to create artificial enamel lesions measuring 4 × 4 mm. Commercial and experimental varnishes were applied to specimens, followed by 24 h of storage in artificial saliva and 7 days of pH cycling. The Scanning Electron Microscope and Energy Dispersive X-ray (SEM-EDX) were employed to assess the specimens at baseline, post-demineralization, post-remineralization, and following pH cycling. Lesion depth was examined by polarized light microscopy (PLM). Statistical evaluation was conducted using Repeated Measures ANOVA, Bonferroni post-hoc, Friedman, Wilcoxon signed-rank one-way ANOVA, Tukey’s post hoc, Kruskal-Wallis, Mann-Whitney, and Pearson correlation tests. EDX showed highly significant intra-group increases in Ca Wt.% for all materials (P < 0.001). Inter-group differences were significant (P < 0.05) after remineralization and pH cycling. After both stages, the Ca/P ratio showed highly significant intra-group changes (P < 0.001) and significant inter-group differences. n-BAG recorded the highest Ca and Ca/P values, while the control showed the lowest. SEM images revealed complete and uniform surface coverage in n-BAG, partial surface recovery in Enamel Pro and n-HAP, and persistent porosities in the control. PLM confirmed the lowest lesion depth in n-BAG. A moderate negative correlation was found between lesion depth and the Ca/P ratio. n-BAG and n-HAP exhibited superior efficiency after pH cycling compared to Enamel Pro, suggesting their potential as preventive agents for managing initial enamel caries in primary teeth.