Influence of Illumination Conditions and Cross‐Polarization on DSLR ‐Based Clinical Tooth Color Assessment: A Comparison With Spectrophotometric Measurements

ABSTRACT Aim To evaluate the influence of different illumination systems and cross‐polarization on tooth color determination using DSLR photography, and to assess the agreement between photographic methods and spectrophotometric measurements. Materials and Methods Thirty‐one participants (62 maxillary central incisors) were included. Color measurements were obtained using a spectrophotometer under standardized conditions. Standardized DSLR photographs were taken using three illumination setups: softbox‐equipped studio flash, twin flash, and twin flash with cross‐polarization filter. The image area corresponding to the 5‐mm probe tip was calculated, and mean L *, a *, and b * values were obtained from all pixels within this region. Color differences (Δ E 00 ) and Δ L , Δ a , Δ b values were calculated. Data were analyzed using repeated measures ANOVA and Friedman tests ( α = 0.05). Results Significant differences were observed among all measurement systems for L *, a *, and b * parameters ( p < 0.001). The highest color difference relative to the spectrophotometer was found in the softbox system (Δ E 00 = 5.69), whereas twin flash (Δ E 00 = 3.56) and cross‐polarized twin flash (Δ E 00 = 3.32) showed lower and comparable values. None of the methods produced color differences within the perceptibility threshold (Δ E 00 ≤ 0.8). The highest proportion of clinically acceptable values (Δ E 00 : 0.8–1.8) was observed in the twin flash group (11.3%). Conclusion Lighting conditions significantly influence tooth color determination using DSLR photography, leading to variations across all color components ( L *, a *, and b *). These findings indicate that different photographic setups may produce inconsistent color outcomes, highlighting the need for standardized imaging protocols in clinical practice. Clinical Significance Illumination conditions significantly influence photographic tooth color measurements, leading to clinically relevant discrepancies. Standardization of photographic protocols is therefore essential for reliable color matching in clinical practice.