Color acceptance of direct dental restorative materials by human observers

Abstract

The purposes of this study were to evaluate the CIELAB, CMC (2:1), and CMC (1:1) formulas to identify which provides the best indicator for acceptability of small color differences in the esthetic dental restorative materials, to determine if different groups of observers have different levels of acceptability, and to estimate the color difference that would indicate acceptability between a restoration and an adjacent tooth. The subject population of human observers was divided into four groups, each containing 12 subjects. The composition of the groups were: Group 1, dental auxiliaries and hygienists; Group 2, dentists; Group 3, dental materials scientists; and Group 4, patients. A color vision screening test was administered to each subject to ensure that only observers with normal color vision were evaluated. A composite resin color discrimination test was developed specifically for this study. This test was composed of six sets of discs fabricated from dental composite resin restorative materials. Each set consisted of one standard disc representing tooth color. In each set, six discs representing composite resin restorations were matched to the standard disc for a total of 36 pairings in the test. Color differences between the standard discs and the restoration discs were calculated in CIELAB, CMC (1:1), and CMC (2:1) color units. The subjects were asked to evaluate the composite resin materials as to acceptability of color differences between the disc pairs. The data were analyzed by logistic regression analysis for each observer and by each ⌬E formula to generate receiver operating characteristics (ROC) curves. The areas under these ROC curves were calculated and ranked. ANOVA and Tukey's Studentized Range (HSD) Test were applied to the ranks. In regard to the acceptance of dental restorations based solely on color difference, the CMC (1:1) color difference formula gave better correlation than the CIELAB formula for small color differences in the esthetic dental restorative materials. There were significant differences found between the experiment groups in regard to acceptability of color differences using the CMC (1:1) and CIELAB formulas. The dental hygienist/auxiliaries group proved to be more discriminating in accepting differences between tooth and composite resin restorative material color than patients. The mean 50:50 ⌬E replacement points for all subjects were 2.29 and 2.72 color units for the CMC (1:1) and CIELAB formulas, respectively.

Effect of Gender, Experience, and Value on Color Perception

“…7,15,21,25,28 Nevertheless, other studies found that this factor was relevant in the frequency of right choices of ceramic shade, which is in agreement with the findings of this current study. [16][17][18][19]31 Experienced clinicians were statistically significantly better at recognizing pairs of equal shades correctly (76.92%) than were the novices (61.98%). Therefore, one can speculate that training is a preponderant factor in correct shade selection.…”

“…In addition, the study evaluated the extent to which the observer's clinical experience, [15][16][17][18][19] the ceramic shade, 20,21 and the value 5,21 had an influence on the choice of shade.…”

In Vivo and in Vitro Evaluations of Repeatability and Accuracy of VITA Easyshade® Advance 4.0 Dental Shade-Matching Device

“…These values remain below the 50% acceptability level of 5.5 dE units, but exceed the 50% of perceptibility threshold for a clinical mismatch in the in vivo model (varies from 2.6 to 3.3 dE units) (5,(23)(24)(25)(26)(27). Since the examiner in this study was trained and well experienced in the color measurements with the tested device and we achived the standardized conditions and illumination, this finding for the in vivo model may be attributed to the tooth variance in surface morphology and the different tooth layers' thickness and transparency.…”

“…Since the examiner in this study was trained and well experienced in the color measurements with the tested device and we achived the standardized conditions and illumination, this finding for the in vivo model may be attributed to the tooth variance in surface morphology and the different tooth layers' thickness and transparency. Although ICCs for the in vivo model in this study coincided in all CIE L*a*b* compontents with those of Lehman, our dE was slightly higher and therefore got on the upper level of clinically visible difference obvious only to a trained eye (23)(24)(25)(26)(27).…”

Color accuracy of commercial digital cameras for use in dentistry

“…The magnitude of perceptible and/or acceptable color difference for human observers is still not well-defined, nor ideally measured in dental color research. Perceptible color differences range from a ΔE of 1 [4] and 2 [5] in in-vitro studies to 3.7 in an in-vivo study [6]; while acceptable color differences can range from a ΔE of 2.72 [7] and 3.3 [8] for in-vitro studies to 6.8 in an in-vivo study [6].…”