AbstractThe objectives of this study were to evaluate the changes in color and color coordinates of dental resin composites after immersion in porcine liver esterase (PLE, 400 mU/mL; a substitute for salivary hydrolase) with CIEDE2000 color system, and to compare those with CIELAB color system. Color of resin composites was measured after immersion in PBS (phosphate buffered saline; control) or PLE up to nine weeks. Color difference (Δ E00) and changes in lightness (L′), red‐green parameter (a′), yellow‐blue parameter (b′), and chroma (C′) with CIEDE2000 system were compared. Correlation in the changes of color with CIEDE2000 and CIELAB systems was determined. Δ E00 values after a 9‐week immersion in PLE were 0.7–2.8, which were not higher than those in PBS except for a few cases. Changes in b′ and C′ values after a 9‐week immersion in PLE were generally lower than those in PBS, and were in the range of −4.0 to −0.1 and −4.0 to −0.1, respectively. Therefore, the influence of porcine liver esterase on the changes of color and color coordinates was negligible with CIEDE2000 color system. There was a significant correlation between color differences (Δ E00 vs ΔE) with CIEDE2000 and CIELAB systems [correlation coefficient (r) = 0.95, p < 0.01]. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 276–283, 2005