Elemental changes in tooth hard tissues during demineralization and fluoride-induced remineralization: an SEM-EDX...

Tooth enamel and dentin are the most highly mineralized tissues in the human body, and their structural stability depends on the balanced content of calcium (Ca), phosphorus (P), and fluoride (F). Demineralization leads to the loss of these ions, weakening the tooth structure and increasing susceptibility to caries.

This study aimed to evaluate elemental changes in Ca, P, and F in intact, demineralized, and remineralized teeth across the enamel, dentin-enamel junction and peripulpal dentin.

45 extracted human teeth were longitudinally sectioned to yield 90 paired specimens. One half of each tooth served as a baseline (intact) control, while the corresponding half was subjected to acid-induced demineralization. Following demineralization, the experimental halves were randomly assigned to one of three remineralization protocols (n = 15 per group): fluoride varnish, fluoride toothpaste with rinsing, and fluoride toothpaste without rinsing. Elemental composition was analyzed using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Statistical analysis included paired t-tests for within-tooth comparisons and one-way ANOVA for treatment effects (p < 0.05).

At baseline, enamel exhibited significantly higher calcium and phosphorus levels compared to dentin regions. Demineralization resulted in a significant reduction in mineral content, particularly in dentin, along with complete loss of detectable fluoride (p < 0.0001). Remineralization increased calcium and fluoride levels across all groups. Fluoride varnish showed the highest fluoride retention trend, particularly in enamel; however, no statistically significant differences were observed among treatment groups for calcium and phosphorus.

Fluoride-based treatments contributed to partial remineralization of tooth hard tissues. Fluoride varnish showed a tendency toward greater fluoride incorporation, particularly in enamel; however, statistically significant superiority over other treatment approaches was not demonstrated. These findings support the role of fluoride in remineralization while highlighting the need for further clinically relevant studies.