Dental ceramics: a CIEDE2000 acceptability thresholds for lightness, chroma and hue differences

Objectives: To determine the visual 50:50% acceptability thresholds for lightness, chroma and hue for dental ceramics using CIEDE2000(K(L):K(C):K(H)) formula, and to evaluate the formula performance using different parametric factors.

Methods: A 30-observer panel evaluated three subsets of ceramic samples: lightness subset (|ΔL'/ΔE(00)| ≥ 0.9), chroma subset (|ΔC'/ΔE(00)| ≥ 0.9) and hue subset (|ΔH'/ΔE(00)| ≥ 0.9). A Takagi-Sugeno-Kang Fuzzy Approximation was used as fitting procedure, and the 50:50% acceptability thresholds were calculated. A t-test was used in statistical analysis of the thresholds values. The performance of the CIEDE2000(1:1:1) and CIEDE2000(2:1:1) colour difference formulas against visual results was tested using PF/3 performance factor.

Results: The 50:50% CIEDE2000 acceptability thresholds were ΔL' = 2.92 (95% CI 1.22-4.96; r(2) = 0.76), ΔC' = 2.52 (95% CI 1.31-4.19; r(2) = 0.71) and ΔH' = 1.90 (95% CI 1.63-2.15; r(2) = 0.88). The 50:50% acceptability threshold for colour difference (ΔE') for CIEDE2000(1:1:1) was 1.87, whilst corresponding value for CIEDE2000(2:1:1) was 1.78. The PF/3 values were 139.86 for CIEDE2000(1:1:1), and 132.31 for CIEDE2000(2:1:1).

Conclusions: There was a statistically significant difference amongst CIEDE2000 50:50% acceptability thresholds for lightness, chroma and hue differences for dental ceramics. The CIEDE2000(2:1:1) formula performed better than CIEDE2000(1:1:1).