Evaluation of the repeatability and matching accuracy between two identical intraoral spectrophotometers: an in vivo and in vitro study

PURPOSE: The purpose of this study was to evaluate the repeatability and matching accuracy between two identical intraoral spectrophotometers. MATERIALS AND METHODS: The maxillary right central incisor, canine, and mandibular left central incisor of each of 30 patients were measured using 2 identical intraoral spectrophotometers with different serial numbers (EasyShade V). The color of each shade tab from 3 shade guides (VITA 3D-Master) was also determined with both devices. All measurements were performed by a single operator. Statistical analyses were performed to verify the repeatability, accuracy, and the differences between the devices with paired t-tests, one-way ANOVA, and intra-class correlation coefficients (ICCs) (α=.05). RESULTS: A high level of measurement repeatability (ICC>0.90) among L(*), a(*), and b(*) color components was observed within and between devices (P<.001). Intra-device matching agreement rates were 80.00% and 81.11%, respectively, while inter-device matching agreement rate was 51.85%. ANOVA revealed no significant different color values within each device, while paired t-test provided significant different color values between both devices. The CIEDE2000 color differences between both devices were 2.28±1.61 ΔE(00) for in-vivo readings. Regarding the clinical matching accuracy of both devices, ΔE(00) values between teeth and matching shade tabs were 3.05±1.19 and 2.86±1.02, respectively. CONCLUSION: Although two EasyShade V devices with different serial numbers show high repeatability of CIE L(*), a(*), and b(*) measurements, they could provide different color values and shade for the same tooth.