Confiabilidade do método de mensuração de cor de resinas compostas por imagens obtidas em lupa estereoscópica

Abstract

This study assessed the reliability of a color measuring method using images obtained from a charge-coupled device (CCD) camera and a stereoscopic loupe. Disc-shaped specimens were built using the composite Filtek Z350 XT (shades DA1, DA2, DA3, and DA4) (n = 3). CIELAB color coordinates of specimens were measured with the spectrophotometer SP60 over white and black backgrounds. Images from the same specimens were acquired with a CCD camera attached to a stereoscope loupe. The image's color was measured (red-green- blue - RGB) using image processing software and converted to CIELAB coordinates. For each color coordinate, data from images were adjusted using linear regressions predicting those from SP60. Whiteness Index (WID) and translucency parameter (TP00) of specimens, and color differences (ΔE00) among pair-wise shades were calculated. Data were analyzed by repeated-measures ANOVA and Tukey`s test (α = 0.05). Images from loupe tended to be darker and redder than the true color. Adjusting data resulted in similar WID, ΔE00, and TP00 to those values observed for the spectrophotometer. Differences were observed only for the WID of the shade DA3, and ΔE00 for comparing DA1 and DA3 over the black background. However, these differences were not clinically relevant. Using adjusted data from images acquired with a stereoscope loupe was a feasible method to measure color.