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Now showing items 1 - 3 of 3

  • Determining color difference thresholds in denture base acrylic resin

    Ren, Jiabao   Lin, Hong   Huang, Qingmei   Zheng, Gang  

    Abstract Statement of problem In restorative prostheses, color is important, but the choice of color difference formula used to quantify color change in acrylic resins is not straightforward. Purpose The purpose of this in vitro study was to choose a color difference formula that best represented differences between the calculated color and the observed imperceptible to unacceptable color and to determine the corresponding perceptibility and acceptability threshold of color stability for denture base acrylic resins. Material and methods A total of 291 acrylic resin denture base plates were fabricated and subjected to radiation tests from zero to 42 hours in accordance with ISO 7491:2000. Color was measured with a portable spectrophotometer, and color differences were calculated with 3 International Commission on Illumination (CIE) formulas: CIELab, CMC(1:1), and CIEDE2000. Thirty-four observers with no deficiencies in color perception participated in psychophysical perceptibility and acceptability assessments under controlled conditions in vitro. These 2 types of assessments were regressed to each observer by each formula to generate receiver operator characteristic (ROC) curves. Areas under the curves (AUCs) were then calculated and analyzed to exclude observers with poor color discrimination. AUCs were subjected to 1-way ANOVA (α=.05) to deter the statistical significance of discriminability among the 3 formulas in terms of perceptibility and acceptability judgments. Student-Newman-Keuls tests (α=.05) were used for post hoc comparison. Results CMC(1:1) and CIEDE2000 formulas performed better for imperceptible to unacceptable color differences, with corresponding CMC(1:1) and CIEDE2000 values for perceptibility of 2.52 and 1.72, respectively, and acceptability thresholds of 6.21 and 4.08, respectively. Conclusions Formulas CMC(1:1) and CIEDE2000 possess higher discriminability than that of CIELab in the assessment of perceptible color difference threshold of denture base acrylic resin. A statistically significant difference exists between perceptibility and acceptability thresholds for denture base acrylic resin.
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  • A novel EDA1 missense mutation in X-linked hypohidrotic ectodermal dysplasia

    Wang, Xu   Zhang, Zhiyu   Yuan, Shuo   Ren, Jiabao   Qu, Hong   Zhang, Guozhong   Chen, Wenjing   Zheng, Shushen   Meng, Lingqiang   Bai, Jiuping   Du, Qingqing   Yang, Dongru   Shen, Wenjing  

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  • Color difference threshold determination for acrylic denture base resins.

    Ren, Jiabao   Lin, Hong   Huang, Qingmei   Liang, Qifan   Zheng, Gang  

    This study aimed to set evaluation indicators, i.e., perceptibility and acceptability color difference thresholds, of color stability for acrylic denture base resins for a spectrophotometric assessing method, which offered an alternative to the visual method described in ISO 20795-1:2013. A total of 291 disk specimens 50=C2=B11 mm in diameter and 0.5=C2=B10.1 mm thick were prepared (ISO 20795-1:2013) and processed through radiation tests in an accelerated aging chamber (ISO 7491:2000) for increasing times of 0 to 42 hours. Color alterations were measured with a spectrophotometer and evaluated using the CIE L*a*b* colorimetric system. Color differences were calculated through the CIEDE2000 color difference formula. Thirty-two dental professionals without color vision deficiencies completed perceptibility and acceptability assessments under controlled conditions in vitro. An S-curve fitting procedure was used to analyze the 50:50% perceptibility and acceptability thresholds. Furthermore, perceptibility and acceptability against the differences of the three color attributes, lightness, chroma, and hue, were also investigated. According to the S-curve fitting procedure, the 50:50% perceptibility threshold was 1.71DeltaE00 (r(2)=3D0.88) and the 50:50% acceptability threshold was 4.00 DeltaE00 (r(2)=3D0.89). Within the limitations of this study, 1.71/4.00 DeltaE00 could be used as perceptibility/acceptability thresholds for acrylic denture base resins.=20
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