• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.13-22
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• 2009

The composite resin, due to its esthetic quality, is considered the material of choice for restoration of anterior teeth. To get a satisfactory result in the composite resin restorations, it is necessary to choose right shade. At present, most of the commercial composite resins are based on the Vita Lumin shade guides or shade guides that are provided by their company, but color differences among them might be expected even using the same shade in various materials. This study is to measure color differences between various light-cured composite resins and shade guides and to provide the clinicians with information which may aid in improved color match of esthetic restoration. Four kinds of light-cured composite resins (Gradia Direct (GD), Z250 (Z250), Clearfil AP-X (AP-X), Esthet X (E X)) and shade guides with A2 and A3 shade were used. Three specimens of each material and one specimen of each shade guide were made. Each composite resin was filled into the Teflon mold (1.35 mm depth, 8 mm diameter), followed by compression, polymerization and polishing with wet sandpaper. Shade guides were grinded with polishing stones and rubber points to a thickness of approximately 1.35 mm. Color characteristics were performed with a spectrophotometer(color i5, GretagMacbeth, USA). A computer-controlled spectrophotometer was used to determine CIELAB coordinates ($L^*$, $a^*$, $b^*$) of each specimen and shade guide. The CIELAB measurements made it possible to evaluate the amount of the color difference values (${\Delta}E^*ab$) between composite resins and shade guides. CIE standard D65 was used as the light source. The results were as follows : 1. Among the $L^*$, $a^*$, $b^*$ values of most of 4 kinds of composite resin specimens which are produced by same shade, there were significant differences(p<0.05). 2. Among all 4 kinds of composite resin specimens which are produced by same shade, there were color differences that is perceptible to human eye(${\Delta}E^*>3.3$). 3. Between most of composite resin specimens investigated and their corresponding shade guides, there were color differences that is perceptible to human eye(${\Delta}E^*>3.3$). 4. In the clinical environment, it is recommended that custom shade guides be made from resin material itself for better color matching. Shade guides supplied by manufacturers or Vita Lumin shade guide may not provide clinicians a accurate standard in matching color of composite resins, and there are perceptible color differences in most of products. Therefore, it is recommended that custom shade guides be made from resin material itself and used for better color matching.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.107-120
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• 1996

복합레진은 조작이 용이하고 강도가 우수하며 중합시간이 짧고 법랑질과 상아질에 접착이 가능하며 연마성이 뛰어나고 자연스러운 색상을 나타내므로 심미적 수복에 가장 일반적으로 선택되는 재료의 하나이다. 대부분의 복합레진 kit에는 shade guide가 포함되어 있어 이를 기준으로 중합된 후의 복합레진 색조를 예상하여 선택하게 된다. 그러나 이러한 shade guide들은 대개 복합레진이 아닌 plastic으로 제조된 것으로 중합된 복합레진의 실제 색조와는 차이가 생기게 되며 결국 shade guide 자체의 문제점으로 인해 이상적인 색조선택이 어려워진다. 이에 본 연구에서는 국내에 시판되고 있는 5종의 복합레진 제품을 선정하여 분광 광도계를 이용해서 shade guide와 중합된 복합레진 사이의 색조차이를 측정, 비교 연구하였다. 직경 16mm. 두께 1.6mm의 plastic mold에 5종의 광중합형 복합레진(Z100, Prisma TPH, Tetric, Silux Plus, Herculite XR)을 충전하고 응축기에 넣어 압축한 후 제조사의 지시에 따라 광중합기로 중합시킨 후 mold에서 시편을 제거하여 보관했다가 젖은 sandpaper 상에서 순차적으로 연마하였다. shade guide는 step부분을 갈아내어 복합레진 시편과 동일한 두께로 만든후 연마하였다. 분광광도계에 shade guide를 넣고 CIE illuminant D65 하에서 spectral reflectance를 측정하고 해당 색조의 복합레진 시편도 통일한 방법으로 측정하고 $L^*$, $a^*$, $b^*$값과 ${\Delta}E^*$값을 얻은후 분석하여 다음과 같은 결과를 얻었다. 1. Z100의 D3, A3, B2 shade와 Prisma TPH의 B2 shade를 제외한 모든 시편에서 shade guide와 복합레진간에 육안으로 인지할 수 있는 색차(${\Delta}E^*$ > 1.0)가 관찰되었다. 2. 평균적으로 Z100이 가장 적은 색차를 나타내었고 Prisma TPH, Tetric, Silux Plus, Herculite XR 순으로 색차가 증가하였다. 3. Prisma TPH의 A2 shade. Tetric의 W shade. Silux Plus의 YB, U shade, Herculite XR의 L, LY shade는 ${\Delta}E^*$값이 3.3 이상으로 나타났다. 4. Z100, Prisma TPH, Tetric, Silux Plus에서는 복합레진보다 shade guide가 더 높은 $L^*$값을 보이는 경향이 나타났으며, Herculite XR에서만 복합레진이 더 높은 $L^*$값을 나타냈다. 5. 모든 시편에서 $b^*$ 값은 (+)로 관찰되었고, Z100, Prisma TPH, Tetric, Silux Plus의 shade guide는 복합레진에 비해 높은 $b^*$값을 보였다. 6. 모든 시편에서 $a^*$값은 (-)로 관찰되었고. Herculite XR 및 Silux Plus에서는 복합레진이 shade guide 에 비 해 낮은 $a^*$값을 나타냈다.

• Restorative Dentistry and Endodontics
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• v.34 no.3
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• pp.199-207
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• 2009

The objective of this study was to evaluate the effect of color measuring instrument by measuring the color of dental composite resins. Nine shade light cured composite resin disks were prepared (diameter : 15 mm, thickness : 4 mm). CIE $L^*a^*b^*$ color scale of each disk was measured with 3 different types of spectrophotometer [MiniScan XE plus (Model 4000S, Hunter Lab, USA), CM-3500d (Minolta, Japan) and Specbos 2100 Miniature VIS Reflection spectrometer (Serial No: 319416, JETI Technishe VIS Instrumentic GmbH. Germany)]. Miniscan XE Plus and CM-3500d using identical measuring geometry with different size of viewing aperture. But Specbos 2100 using different measuring geometry. Within the limitation of this study, there were color difference (${\Delta}E^*$) from 2.4 to 7.8 between Miniscan XE Plus and CM-3500d, but $L^*$, $a^*$, $b^*$ values showed the high correlation. However, there were great color difference (${\Delta}E^*$) in the extent of about 20 between instruments with the different measuring geometry. Therefore, color scale measured by color measuring instrument should be used as a relative value rather than an absolute value in the field of dentistry.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.473-479
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• 2003

The purpose of this study is to recover the CIE XYZ tristimulus values of original colors from scanner output signals, and to reproduce true colors on the monitor. The process of this study is composed of three steps; scanner characterization, chromatic adaptation transformation, and color space transformation between and sRGB. Especially, in the process of recovery, scanner stimuli were obtained accurately by dividing the non-linear photometric response curve into two parts. As the result of test to EPSON Expression 1680 scanner, the average color difference between true and recovered XYZ for 228 target colors, 22 test neutrals, and 36 test colors were 1.49, 0.97, and 1.42 $\Delta$ $E_{UV}$ *, respectively. With the transformation from illuminant D50 to illuminant D65, the input signals to sRGB monitor were predicted. Finally, it could be found that displayed colors with predicted input signals were very consistent with true colors. with true colors.

• Journal of dental hygiene science
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• v.12 no.2
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• pp.123-129
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• 2012

The aim of study was to compare the color parameters and mean color difference of porcelain specimens by different veneering technique in order to examine the effect of veneering technique on esthetics of yttria-stabilized tetragonal zirconia polycrystalline(Y-TZP) all ceramic restoration. Three groups of square-shaped core ceramic specimens(14mm in diameter and 0.3, 0.5, 0.7 mm) and two groups of veneering ceramic specimen were prepared for analysis. Color parameter($L^*,a^*,b^*$) and color difference of zirconia core squares and core-veneer specimens were measured with ShadeEye $NCC^{(R)}$ spectrophotometer, respectively. Mean color difference(${\Delta}E^*$)were calculated using color difference formula. Two-way analysis of variance(ANOVA) combined with a Tukey multiple-range test were used to analysis the data(${\alpha}=0.05$). ${\Delta}E^*$ values were not significantly affected by core thickness and veneering porcelain(p=0.083). The color differences(${\Delta}E^*$) of core-veneer specimens with 0.5, 0.7 mm-A1,A2,A3.5 shade were mostly below 3.7 which was within the clinically acceptable range, while color differences between 0.3 mm-A1,A2 showed more than 3.7. All-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.233-242
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• 2018

The purpose of this study is to evaluate the effect of resin cement color on the color of commercially available zirconia crown. The zirconia and resin cements used for the experiment were $NuSmile^{(R)}$ ZR Zirconia LT Shade (LT), $RelyX^{TM}$ U200 TR, A2, and A3O (TR, A2, A3O). The disks of zirconia and resin cements with diameters of 5 mm and thicknesses of 1 mm were prepared. Five disks were made for each specimen. The CIE $L^*a^*b^*$ values of zirconia, resin cements and the combinations thereof were measured on black and white backgrounds, respectively, using a spectrophotometer. The color effect of resin cement on the color of the zirconia crown was evaluated by calculating translucency parameter (TP), contrast ratio (CR), and color differences (${\Delta}E{^*}_{ab}$) based on the measured CIE $L^*a^*b^*$ values. The statistical significances were verified by one-way ANOVA and the Tukey-multiple comparisons tests. As a result, the TP and CR values were decreased (p<0.05) and increased, respectively, in the combination of zirconia and resin cement disks compared to zirconia disk per se. When using the black background, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of the zirconia and three resin cement disks were imperceptible level. The A3O showed the lowest ${\Delta}E{^*}_{ab}$ value among three resin cements. When using the white background, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of zirconia and TR resin cement (LT/TR) disks showed acceptable level. However, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of zirconia and A2 resin cement (LT/A2) disks showed unacceptable level. Meanwhile, the ${\Delta}E{^*}_{ab}$ values between zirconia and the combination of zirconia and A3O resin cement (LT/A3O) disks showed perceptible but acceptable level. Within the limits of this study, the colors of resin cements did not cause unacceptable color changes of zirconia except the combination of LT/A2 on the white background. The resin cement that gave the least color changes to zirconia was A3O. This means that the resin cement A3O is recommended to use for minimizing color changes when cementing commercially available zirconia crown to tooth.

• The Journal of Natural Sciences
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• v.8 no.1
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• pp.137-143
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• 1995

The purpose of this study is to investigate the change of shrinkage, tensile strength, elasticity, light-fastness and color-fastness of 100% cotton upper under wear after acidic treatment and repeated washing and drying. Both of warp and welt were shrinked, especially in the early washing stage. Tensile strength was not weakened by 15 times of repeated washing. Hunter whiteness(HW) of white-underwear decreased, but color difference($\Delta$E) and yellow index(YI) increased corresponding to the frequency of washing and sunlight drying. The discoloration of color-underwear was significant in the early stage.

• Journal of dental hygiene science
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• v.12 no.4
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• pp.342-347
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• 2012

This study is a temporary crowns and the period you want to avoid the exposure of the coffee girl polymerization types is difficult given the temporary tolerance by producing resin. 1. Change of brightness ($L^*$) edge in time increases, distilled water, Americano, Cafelatte, Vanillalatte was reduced to a significant level of brightness (p<.001). The most significant decrease in brightness of the Americano, which tend to grow out of a Cafelatte, Vanillalatte, which was followed by distilled water. 2. Change of redness ($a^*$) edge in time tend to increase saturation increases, the redness value of Americano, Cafelatte, redness value was a statistically significant difference in distilled water and Vanillalatte (p<.05) was not significant. 3. Change of yellowness ($b^*$) edge in time tend to increase saturation increases, the yellowness value of Cafelatte, Vanillalatte, Americano, except for distilled water at the saturation of yellowness value were no statistically significant (p<.05). 4. Change of color difference (${\Delta}E^*$) in order of (Americano>Cafelatte>Vanillalatte) as time of immersion increases change of color difference appear and no statistically significant (p<.05). Americano, the edge, since there can be more than chrominance is 3.3 uses station than a Vanillalatte, Cafelatte and discoloration when edge in 28, since even in the one to two difficult to distinguish with the naked eye as a discoloration. It was no difference statistically in color difference (${\Delta}E^*$) value in distilled water (p>.05).

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.183-189
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• 2004

As high quality digital cameras become readily available, digital cameras are being used not only for simple picture recording but also as information storing media in various fields. However, due to the fact that the spectral responses of the camera sensors are different from color matching functions of the CIE standard observer, the color can not be measured using these cameras. This study shows a method for converting camera image to sRGB image, in which color information is preserved. The transfer matrix between camera output signals and CIE stimulus values was determined using a multiple regression method with Macbeth ColorChecker as target colors. The CIE stimulus values for camera output signals can be mapped with a transfer matrix, and these values are converted to sRGB signals. As the result of testing a Kodak DC220 digital camera, the average color difference of Macbeth ColorChecker between true and displayed colors was 2.1 $\Delta$ $E_{ab}$ $^{*}$.$^{*}$.

• Journal of Conservation Science
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• v.25 no.4
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• pp.465-471
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• 2009

In this study, the substitution fumigation gases (15% Ethylene Oxide + 85% HFC 134a, 20% Ethylene Oxide + 80% $CO_2$, 99% Sulfuryl Fluoride + 1% Inert Gas) were applied on the metal, pigment, fabric and paper specimen. The result of the fumigation treatment with 15% Ethylene Oxide + 85% HFC 134a (200g/$m^3$, 48hours) is the color changes (${\Delta}E$) of 1st and 2nd Cu specimens showed significant difference as 3.40, 4.17. On the other hand, other specimens except for Cu showed less than 3.0 in chrominance values. The result with 20% Ethylene Oxide + 80% $CO_2$ (150g/$m^3$, 48hours) is that the color changes (${\Delta}E$) of 1st and 2nd specimens were overall less than 3.0 so that color differences were subtle and hardly recognized with naked eyes. So it is proved that the fumigation treatment with Ethylene Oxide 20% + $CO_2$ 80% is relatively stable on materials in this study. In the case of 99% Sulfuryl Fluoride + 1% Inert Gas (50g/$m^3$, 48hours), the color difference of Lead red ($PbO_4$) of pigment was more than 3.0 that was compared with contrast specimens. But chrominance values in the other specimens were less than 3.0 on average.