Comparative Evaluation of Time-Dependent Enamel Demineralization Using Micro-Computed Tomography, Laser Fluorescence, and Colorimetric Image Analysis

Background: Early detection and monitoring of enamel changes during caries lesion formation are essential for preventive management. This study aimed to evaluate time-dependent enamel demineralization using micro-computed tomography (micro-CT) and to compare its diagnostic performance with laser fluorescence and digital colorimetric image analysis. Methods: Twelve sound human permanent teeth were subjected to a gel-based lactic acid demineralization for 14 days. Assessments were performed at baseline and after 3, 7, and 14 days. Enamel mineral density (MD) and demineralization depth (DD) were measured using micro-CT. Laser fluorescence was evaluated using DIAGNOdent, while colorimetric changes were analyzed through standardized digital imaging using the CIE Lab* system, including ΔE and Whiteness Index (WI). Statistical analysis included repeated measures ANOVA and Pearson correlation (p < 0.05). Results: A significant time-dependent progression of enamel demineralization was observed. Demineralization depth increased from 0.0828 mm (3 days) to 0.234 mm (14 days) (p < 0.001), while mineral density decreased significantly over time (p < 0.001). DIAGNOdent values showed significant increases after 7 and 14 days (p = 0.002). Colorimetric analysis revealed early detectable changes, with ΔE exceeding clinically perceptible thresholds as early as day 3. WI values increased progressively, indicating enhanced enamel opacity. A weak but significant negative correlation between MD and DD was found (p = 0.04). Conclusions: Enamel demineralization progresses in a time-dependent manner and can be effectively monitored using micro-CT, laser fluorescence, and colorimetric analysis. Digital colorimetric analysis may serve as a valuable adjunctive tool in caries diagnostics.