Correlations between spectroradiometric and spectrophotometric colors of all-ceramic materials.

OBJECTIVES Color coordinates of translucent esthetic materials measured by traditional spectrophotometers (SP) would deviate from those measured by newly introduced spectroradiometers (SR), which might simulate the clinical viewing condition better. This study aimed to determine the correlations in the SP- and SR-based color coordinates and color differences of all-ceramic materials. METHODS Specimens for seven A2 shade core ceramics (n=7) and corresponding A2 and A3 shades veneer ceramics (n=7) were fabricated in clinically relevant thicknesses (1.5mm after layering). Color of layered specimens was measured according to the CIELAB color scale by a SP and a SR. Color differences (ΔE(ab)(*)) between the reference ceramics and the corresponding layered ceramics were calculated. Correlations between SP- and SR-based color coordinates and color difference values were determined (α=0.05). RESULTS SR-based color coordinates were significantly different from the SP-based values; however, general shifting trends by the instrument were observed. SP- and SR-based CIE a*, b* and chroma values showed significant correlations (p<0.05); however, the CIE L* values and the color differences with the reference showed no significant correlations (p>0.05). SIGNIFICANCE The color coordinates representing the hue attribute (CIE a*, b* and chroma) measured by a spectrophotometer and a spectroradiometer showed significant correlations; however, the color coordinates and the color difference values were significantly different by the instrument. Therefore, color coordinates and the color difference values based on different instruments should not be compared directly.