Harmonization of color measurements for dental application

This multicenter study evaluated the effect of harmonizing spectrophotometric (d/8°) color measurements by using actual dental materials of clinically relevant thickness and translucency as “calibration tiles.” Ten tooth‐colored, 1‐mm thick, resin‐ and ceramic‐based materials were tested at the coordinating center ( CC ) and six research sites ( RS ). Correction factors were calculated for each material and each site to obtain the corrected reflection spectra from the non‐corrected data set. Non‐corrected ( NC ) and corrected ( C ) reflection values were converted into CIEDE2000 and CIELAB color parameters for the following comparisons: CC vs RS NC and CC vs RS C , between RS NC vs RS NC and RS C vs RS C pairs, and among RS separately (α = 0.05). Mean color differences for CC vs RS NC and corresponding CC vs RS C values were ΔE 00 = 4.2 (2.6) and ΔE 00 = 0.7 (0.6), respectively. Corresponding values for RS NC vs RS NC and RS C vs RS C specimen pairs were Δ E 00 = 5.9 (2.9) and Δ E 00 = 1.0 (0.5), respectively. The CIEDE2000 NC vs C comparison for each research site separately ranged from 0.5 to 8.5. Color differences of CC vs RS C and RS C vs RS C pairs decreased 83% to 84.5% as compared with respective color differences for non‐corrected research site measurements and was RS dependent ( P  < .001). The obtained results validated the proposed method of harmonizing color measurements for dental application as a reliable quality control tool for dental research laboratories and industry.