Objective Measurement of Tooth Color Using Spectrophotometry and ICDAS : Quantifying CIELAB Color Changes Across Caries Severity

OBJECTIVE: The International Caries Detection and Assessment System (ICDAS) is widely used for early caries detection but relies on visual interpretation. Although spectrophotometry objectively quantifies tooth color, variation across ICDAS categories and its relationship with lesion severity remain unclear. The present in vitro study therefore characterized spectrophotometric measurements across ICDAS categories, evaluated their association with severity, and quantified differences across categories. MATERIALS AND METHODS: Three hundred unrestored extracted posterior teeth were classified as ICDAS 0-4 by a calibrated examiner. CIELAB values were obtained with a Spectrophotometer at five standardized sites per tooth under controlled lighting and aggregated to tooth-level. Differences across categories were analyzed using ANOVA/Kruskal-Wallis with correlation and regression analysis. Color differences (ΔE00) were calculated relative to the ICDAS 0 (reference) and interpreted using published perceptibility and acceptability thresholds. RESULTS: Color parameters differed significantly across ICDAS categories (p < 0.001). ΔE00 increased from ICDAS 2, exceeding reported perceptibility and acceptability thresholds. With increasing severity, L* decreased while a* and b* increased with significant monotonic associations for all color parameters (ρ = -0.58 to 0.62; p < 0.001). CONCLUSIONS: Statistically significant differences in spectrophotometric color measurements were observed across caries severity categories, with progressive reductions in lightness and corresponding increases in red and yellow chromatic components. Overall color differences were greater in higher severity categories and exceeded perceptibility and acceptability thresholds from moderate lesion stages onward. CLINICAL SIGNIFICANCE: Spectrophotometric color assessment provides an objective framework for quantifying enamel changes associated with caries progression. Color differences exceeding established perceptibility and acceptability thresholds indicate clinically appreciable changes beyond early lesion stages, supporting the use of color-based metrics as an adjunct to conventional visual assessment.