Standard Illuminant D65 Research Articles

FM 100 색상검사를 이용한 표준광원 D65, TL84, A에서의 색채지각

FM 100 색상검사를 이용한 표준광원 D65, TL84, A에서의 색채지각

Efficient semitransparent organic solar cells with good color perception and good color rendering by blade coating

This paper proposes high efficiency semitransparent organic solar cells (OSCs) with good color perception and good color rendering using blade coating technique. We investigate four different polymer blends and first fabricate small area devices with active area of 0.04 cm2, followed by large area devices with active area of 10.8 cm2. Two of the polymer blends, 2,6-Bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene:6,6-phenyl C71-butyric acid methyl ester (PBDTTT-CT:PC71BM) and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b′] dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]:PC71BM (PBDTTT-EFT:PC71BM) show promising results. For small area devices, semitransparent PBDTTT-CT:PC71BM and semitransparent PBDTTT-EFT:PC71BM achieve a power conversion efficiency (PCE) of 5.2% (opaque PCE = 7.5%) and 5.6% (opaque PCE = 9.4%) respectively. For large area devices, they are found to produce a PCE of 3.8% (opaque PCE = 4.2%) and 5.3% (opaque PCE = 5.9%) respectively. Based on the CIE 1931 chromaticity diagram, semitransparent PBDTTT-CT:PC71BM and semitransparent PBDTTT-EFT:PC71BM are located very close to the standard illuminant D65, indicating good color perception. As for color rendering, they demonstrate high color rendering index (CRI) of 95.4 and 87.1 respectively. These combined high performances indicate high-quality transmitted light, which is suitable for window application.

Color Stability Assessment of Two Different Composite Resins with Variable Immersion Time Using Various Beverages: An In vitro Study.

Purpose of the Study:The aim of the study was to evaluate the difference in the color of microhybrid (MH) and nanofilled (NF) composite resins after 24 and 48 h in beverages such as red wine (RW), Coca-Cola, and distilled water. The specific objective of this study was to investigate the cumulative effect of the colorant solutions on the dental composites.Materials and Methods:MH and NF composite resins (A2 shade) were used in this current study. Sixty disk-shaped material specimens (10 mm in diameter × 2 mm in thickness) were prepared using a fiber mold (ring), with the desired dimensions. The specimen surfaces were polished using super-snap polishing system. Sixty specimens were divided into two groups of 30 each (Group I: MH resin composite; Group II: NF resin composite). Both the groups divided into six subgroups (Subgroup I: RW for 24 h [RW-24]; Subgroup II: RW for 48 h; Subgroup III: Coca-Cola for 24 h [CC-24]; Subgroup IV: Coca-Cola for 48 h [CC-48]; Subgroup V: Distilled water for 24 h [DW-24]; Subgroup VI: Distilled water for 48 h [DW-48]). All the samples were immersed in respective drinks for a period of 24 h, and color differences were measured using ultraviolet spectrophotometer. Once again, all the samples were immersed for another 24 h in the same drinks. After 48 h, the color change of the samples was measured. Measurements were made according to the CIE L × a × b × color space relative to the CIE standard illuminant D65. The color changes of the specimens were evaluated using the following formula: Statistical analysis was performed. The data were analyzed using the one-way ANOVA and t-test at a significance level of 0.05.Conclusion:Color stability of MH composite resin was found to be inferior than the NF resin composite irrespective of immersion medium and time. In RW, the color change observed was maximum for both composite resins followed by Coca-Cola. Immersing the resin composites in distilled water for 24 and 48 h had negligible color change. A 48-h immersion of both composite resins in all three immersion mediums showed greater color change than 24 h immersion.

LED-based Vis-NIR spectrally tunable light source - the optimization algorithm

A novel numerical method for calculating the contributions of individual diodes in a set of light emitting diodes (LEDs), aimed at simulating a blackbody radiation source, is examined. The intended purpose of the light source is to enable calibration of various types of optical sensors, particularly optical radiation pyrometers in the spectral range from 700 nm to 1070 nm. This numerical method is used to determine and optimize the intensity coefficients of individual LEDs that contribute to the overall spectral distribution. The method was proven for known spectral distributions: “flat” spectrum, International Commission on Illumination (CIE) standard daylight illuminant D65 spectrum, Hydrargyrum Medium-arc Iodide (HMI) High Intensity Discharge (HID) lamp, and finally blackbody radiation spectra at various temperatures. The method enables achieving a broad range of continuous spectral distributions and compares favorably with other methods proposed in the literature.

Spectral data compression using weighted principal component analysis with consideration of human visual system and light sources

This paper proposed two weight functions based on principal component analysis (PCA) to reserve more colorimetric information in spectral data compression process. One weight function consisted of the CIE XYZ color-matching functions representing the characteristic of the human visual system, while another was made up of the CIE XYZ color-matching functions of human visual system and relative spectral power distribution of the CIE standard illuminant D65. The improvement obtained from the proposed two methods were tested to compress and reconstruct the reflectance spectra of 1600 glossy Munsell color chips and 1950 Natural Color System color chips as well as six multispectral images. The performance was evaluated by the mean values of color difference under the CIE 1931 standard colorimetric observer and the CIE standard illuminant D65 and A. The mean values of root mean square errors between the original and reconstructed spectra were also calculated. The experimental results show that the proposed two methods significantly outperform the standard PCA and another two weighted PCA in the aspects of colorimetric reconstruction accuracy with very slight degradation in spectral reconstruction accuracy. In addition, weight functions with the CIE standard illuminant D65 can improve the colorimetric reconstruction accuracy compared to weight functions without the CIE standard illuminant D65.

Technical Note: Gray tracking in medical color displays-A report of Task Group 196.

The authors discuss measurement methods and instrumentation useful for the characterization of the gray tracking performance of medical color monitors for diagnostic applications. The authors define gray tracking as the variability in the chromaticity of the gray levels in a color monitor. The authors present data regarding the capability of color measurement instruments with respect to their abilities to measure a target white point corresponding to the CIE Standard Illuminant D65 at different luminance values within the grayscale palette of a medical display. The authors then discuss evidence of significant differences in performance among color measurement instruments currently available for medical physicists to perform calibrations and image quality checks for the consistent representation of color in medical displays. In addition, the authors introduce two metrics for quantifying grayscale chromaticity consistency of gray tracking. The authors' findings show that there is an order of magnitude difference in the accuracy of field and reference instruments. The gray tracking metrics quantify how close the grayscale chromaticity is to the chromaticity of the full white point (equal amounts of red, green, and blue at maximum level) or to consecutive levels (equal values for red, green, and blue), with a lower value representing an improved grayscale tracking performance. An illustrative example of how to calculate and report the gray tracking performance according to the Task Group definitions is provided. The authors' proposed methodology for characterizing the grayscale degradation in chromaticity for color monitors that can be used to establish standards and procedures aiding in the quality control testing of color displays and color measurement instrumentation.

Thickness dependence of light transmittance, translucency and opalescence of a ceria-stabilized zirconia/alumina nanocomposite for dental applications

ObjectivesThis study was conducted to investigate thickness dependence of light transmittance, translucency and opalescence of a commercially available fully-sintered ceria-stabilized zirconia/alumina nanocomposite for dental all-ceramic restorations. MethodsThree disk samples of 16mm in diameter and thickness ranging from 0.2 to 0.6mm with 0.1mm increment each were cut from a fully-sintered rod-shaped Ce-TZP/alumina nanocomposite (NANOZR, Panasonic Healthcare, Japan) and polished flat by using diamond slurry. Spectral light transmittance data under the CIE standard illuminant D65 were recorded at 10nm intervals from 360 to 740nm using a computer-controlled spectrophotometer. Average transmittance, translucency and opalescence parameters were determined as a function of sample thickness. Optical properties of a fully-sintered yttria-stabilized tetragonal zirconia polycrystals (Cercon® base, DeguDent GmbH, Germany) were also investigated as a reference. Two-way ANOVA was performed to determine the significant differences in various optical parameters among types of ceramic and thicknesses at α=0.05. ResultsResults of the two-way ANOVA showed that the average transmittance, translucency and opalescence parameters of both ceramic materials were significantly influenced by the type of ceramic and thickness (p<0.001). Light transmittance of the NANOZR was significantly lower than that of the Cercon® base. For both ceramic materials, average transmittance of light and translucency parameter decreased with sample thickness following exponential functions. The NANOZR showed substantially higher opalescence parameters exceeding 20 CIE units when the sample thickness was nearly 0.3mm. The prominent characteristics of high opalescence and low transmittance of light in the NANOZR was considered to be caused by its specific very fine interpenetrated intragranular microstructure and by a large difference of refractive indices of Ce-TZP and alumina components. SignificanceHigh opalescence and low transmittance of light of the ceria-stabilized zirconia/alumina nanocomposite (NANOZR) are attractive properties for use as a substructure in fabricating porcelain-veneering-type esthetic all-ceramic restorations.

Colour of Stone Slabs under Different Standard Illuminations

Spectral measurements have been carried out on polished stone slabs to show the accuracy of theoretical colorimetric calculations on perceptual differences of color appearance under various standard illuminations. Effects of the different spectral characteristics of the light source on colorization of the samples have been also studied to analyze the changes of color sensation on the samples in connection with the changes on the type of the illuminating source. Solar light (Standard Illuminant D65), basic incandescent source (Standard Illuminant A) and a basic fluorescent source (Standard Illuminant F11) have been tested on Tardos red limestone, Siklos green limestone, Carrara white and gray marbles and diorite samples. Colorizing effects of the examined illuminations are compared to Standard Illuminant E – the theoretically perfect white source.

THE EFFECT OF THICKNESS ON THE OPTICAL PROPERTIES OF ENAMIC HYBRID CERAMIC COMPARED TO VITA FELDSPATHIC ONE: IN VITRO STUDY

Aim of the study: The aim of the study was to evaluate the effect of thickness on the translucency parameter of Enamic hybrid ceramic compared to feldspathic ceramic (Markll) ceramic. Materials and Methods: Forty ceramic discs were fabricated using IsoMet 4000 (Buehler, USA) from CAD-CAM blocks of vita Enamic (n=20) and vita Markll ceramic material (n=20). The samples was made into two different thicknesses (0.8 mm – 1.5 mm). One standard shade according to vita 3D master shade guide (VITA Zahnfabrik, Bad Sackingen, Germany), (2M2) was used with all the samples. Finishing and polishing procedures carried out through manufacturer instruction for each ceramic material. Translucency parameter were analyzed and measured using a scanning spectrophotometer (UV- Shimadzu 3101 PC, Chiyoda-ku, Tokyo, Japan). Color measurements (L*, a* and b*) to the samples placed against an ideal white background (CIE L* = 96.68, a*=_0.18, and b*=_0.22) and against an ideal black background (CIE L* = 1.15, a*=_0.11, and b*=_0.50) relative to the standard illuminant D65. All the samples was subjected to measurements for each material type, different thicknesses, the same observer carried out the measurements. Three readings was taken and the mean values were tabulated and analyzed. Three way-ANOVA was used to study the effect of ceramic materials and thickness on Translucency Parameter (TP). Tukey’s post-hoc test was used for pair-wise comparison between the means when ANOVA test is significant. One-Way ANOVA used to compare between the interaction between variables for mean Translucency parameters. Results: Vita Mark II feldspathic ceramic (18.74±3.33) showed the highest statistical significant mean translucency value compared to Vita Enamic hybrid ceramic (12.59±2.96) at p≤0.001*. Thickness of 0.8 mm (18.31±3.71) showed the highest statistical significant mean translucency value compared to 1.5 mm thickness (13.02±3.34) at p≤0.001*. Conclusions: Vita Mark II Feldspathic ceramic are more translucent than Vita Enamic Hybrid ceramic. Increasing the thickness as well as thermocycling decrease the translucency parameter for both ceramic materials.

Highly Efficient Semitransparent Polymer Solar Cells with Color Rendering Index Approaching 100 Using One-Dimensional Photonic Crystal

Window application is the important aim for semitransparent solar cells (STPSC) investigation. Here, we demonstrate a method to achieve significantly improved color rendering index (CRI), depressed chromaticity difference (DC), and enhanced power conversion efficiency (PCE) simultaneously by introducing the one-dimensional photonic crystals (1DPCs) Bragg reflector structure onto the STPSC. The device performance is studied from aspects of color perception, electrical properties, and theoretical optical simulations. The STPSCs exhibit achromatic transparency nature color perceptions, especially for the STPSCs with 1DPCs (pairs ≥ 3) under AM 1.5G illumination light source, standard illuminant D65, and standard illuminant A. The excellent CRI is approaching 97 with lower DC about 0.0013 for the device with 5 pairs of 1DPC illumined by AM 1.5G illumination light source. At the same time, the PCE of STPSC devices with 5 pairs of 1DPC was improved from 4.87 ± 0.14% to 5.31 ± 0.13% compared to without. This method provides a facilitative approach to realizing excellent SPTSC window application.

Optimal illumination for local contrast enhancement based on the human visual system.

The observed color of an object is influenced by the spectral distribution of an illuminant impinging upon it. Here we explored a method to obtain optimal illumination spectra for local contrast enhancement based on human vision. First, multispectral imaging was used to measure the spectral reflectance of the sample and color segmentation was used to extract its color features. Then we obtained the target-specific optimal illumination by maximizing the color differences of mutual colors in our sample tissue. To verify the effectiveness of this method, simulated images under the optimized illumination were compared to illumination with the standard illuminant D65 and a cool white light-emitting diode (5500 K). Results showed that the sample under the optimized illumination had a better perceptual color contrast.

Effect of the number of coloring liquid applications on the optical properties of monolithic zirconia

ObjectiveThis study was aimed to investigate the effect of the number of coloring liquid applications on the optical properties of monolithic zirconia. MethodsEighteen monolithic zirconia specimens (27.6mm×27.6mm×2.0mm) were fabricated and divided into 6 groups (n=3). Each group was designated by the number of A2-coloring liquid applications (Group I to Group V) and Group O as a control. Color and spectral distribution of the specimens were measured with a double-beam spectrophotometer. CIE L*, a* and b* relative to the standard illuminants D65 were measured in reflectance and transmittance modes. Color difference (ΔEab*), translucency parameter (TP) and opalescence parameter (OP) were calculated. All measurements were performed on five different areas of each specimen. All data were analyzed by ANOVA and multiple comparison Scheffé test, Pearson correlations and linear regression analysis (α=0.05). ResultsWith the increase of the number of coloring liquid applications, CIE L* (R2=0.878) and OP values (R2=0.701) were decreased, but CIE b* (R2=0.938) was increased. However, TP values were not significantly changed. The color differences among groups ranged from 1.3 to 15.7 ΔEab* units. Strong correlation was found between OP and Δb* (R2=0.982, P<.01). SignificanceWithin the limitations of this study, it can be concluded that the number of coloring liquid applications with a single shade affects the lightness, yellow chromaticity and opalescence of monolithic zirconia, although its translucency cannot be controlled by the coloring procedure.

Iron(II) acetylacetonate containing brightener and sulphur containing carrier in nickel plating

The effects of an iron(II) acetylacetonate containing brightening agent and a carrier on colour and mechanical properties of nickel plating were investigated to determine optimal electroplating process parameters. The brightening agent contained metasulphobenzaldehyde, pyridine-3-sulphonic acid, p-vinylbenzenesulfonic acid, o-benzoylsulphonamide, sodium saccharine and iron(II) acetylacetonate. The carrier comprised sodium saccharine and sodium allyl sulphonate in water. Plating colour was analysed by visible region spectrophotometry at 350 nm under 6500 K illumination (CIE Standard Illuminant D65). Electron microscopy confirmed that carrier facilitated nickel deposition onto the surface and increased cohesion, thus allowing complete coverage. Moreover, brightening agent increased the bath pH, while carrier did not. In bending experiments on a coated plate, brightening agent increased hydrogen embrittlement, although desired decorative appearance was obtained. Finally, the optimum concentrations of carrier and brightening agent were found to be 12 and 0·4 g L−1 respectively.

Effect of resin shades on opacity of ceramic veneers and polymerization efficiency through ceramics

ObjectivesThe aim of this study was to assess the effect of different resin cement shades on the opacity and color difference of ceramics and to determine the polymerization efficiency of the resin cement at different shades after curing through ceramics. MethodsTwo different ceramics (IPS e.max Press and IPS Empress®CAD, Ivoclar Vivadent) were used for this study. A light-cured veneer luting resin (Variolink Veneer, Ivoclar Vivadent) in four different shades of HV+1, HV+3, LV−1, and LV−3 was used for the colorimetric measurements. The color and spectral reflectance of the ceramics were measured according to the CIELab color scale relative to the standard illuminant D65 on a reflection spectrophotometer (ColorEye7000A, USA). Color differences (ΔE values) and the contrast ratios (CR) of the different groups of samples were calculated. In order to analyse the polymerization efficiency of the resin cements, the micromechanical properties of the resins were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). The results were analysed using one-way ANOVA and Tukey's HSD post hoc tests (SPSS 18.0). ResultsThe one-way ANOVA test showed that the values of ΔE and CR of the different specimen groups were significantly different (p<0.05). Group 1 (20.7±0.5) (IPS-CAD without resin cement) exhibited the highest and group 10 (14.8±0.5) (e.max:HV+3) exhibited the lowest ΔE value. Significant differences in the micromechanical properties were identified among the tested resin cements in different shades (p<0.05). ConclusionsResin cement shade is an important factor for the opacity of a restoration. Furthermore, the resin shade affects the micromechanical properties of the underlying resin cement.

Effect of polishing and glazing on the color and spectral distribution of monolithic zirconia

PURPOSEThe aim of this study was to evaluate the effect of polishing and glazing on the color and spectral distribution of monolithic zirconia.MATERIALS AND METHODSForty-five monolithic zirconia specimens (16.3 mm × 16.4 mm × 2.0 mm) were fabricated and divided into 5 groups according to the number of A2-coloring liquid applications (Group I to V). Each group was divided into 3 subgroups according to the method of surface treatments (n=3): N: no treatment; P: polishing; G: glazing. Color and spectral distribution of five different areas of each specimen were measured according to CIELAB color space in the reflectance mode relative to the standard illuminant D65 on a reflection spectrophotometer. Data were analyzed using one-way ANOVA followed by Tukey's HSD test, Pearson correlation and regression analysis (α=.05).RESULTSThere was a significant difference in CIE L* between Subgroup N and P, and in CIE b* between Subgroup P and G in each group. Spectral reflectance generally decreased in Subgroup P and G in comparison with Subgroup N. Color differences between Subgroup P and G were within the perceptibility threshold (ΔE*ab< 3.7) in most groups. Highly significant correlation was found between CIE b*and each subgroups as the number of coloring liquid applications increased (R2>0.88, P<.001).CONCLUSIONA perceptible color difference can be detected after polishing of monolithic zirconia. Polishing decreases the lightness, and glazing also decreases the lightness, but increases the yellowness of monolithic zirconia.

Perceived color shift of ceramics according to the change of illuminating light with spectroradiometer

PURPOSEPerceived color of ceramics changes by the spectral power distribution of ambient light. This study aimed to quantify the amount of shifts in color and color coordinates of clinically simulated seven all-ceramics due to the switch of three ambient light sources using a human vision simulating spectroradiometer.MATERIALS AND METHODSCIE color coordinates, such as L*, a* and b*,of ceramic specimens were measured under three light sources, which simulate the CIE standard illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp). Shifts in color and color coordinate by the switch of lights were determined. Influence of the switched light (D65 to A, or D65 to F9), shade of veneer ceramics (A2 or A3), and brand of ceramics on the shifts was analyzed by a three-way ANOVA.RESULTSShifts in color and color coordinates were influenced by three factors (P<.05). Color shifts by the switch to A were in the range of 5.9 to 7.7 ΔE*abunits, and those by the switch to F9 were 7.7 to 10.2; all of which were unacceptable (ΔE*ab > 5.5). When switched to A, CIE a* increased (Δa*: 5.6 to 7.6), however, CIE b* increased (Δb*: 4.9 to 7.8) when switched to F9.CONCLUSIONClinically simulated ceramics demonstrated clinically unacceptable color shifts according to the switches in ambient lights based on spectroradiometric readings. Therefore, shade matching and compatibility evaluation should be performed considering ambient lighting conditions and should be done under most relevant lighting condition.

Vitapan 3D-master shade guide showed no fluorescence emission

To determine the fluorescence property of Vitapan 3D-Master shade guide tabs with a spectrophotometer. Fluorescence property of 29 shade tabs, in both of original and ground-to-flat forms, was determined by a reflection spectrophotometer. Color difference (ΔE*ab-FL) by the inclusion and exclusion of the UV component of a standard daylight simulator (CIE standard illuminant D65) was calculated to determine the fluorescence color change. Fluorescence peak was expressed as the difference in spectral reflectance values by the UV component. ΔE*ab-FL values were in the range of 0.2 to 2.7 (mean: 1.2 ± 0.6) for the original and 0.5 to 1.6 (mean: 0.9 ± 0.1) for the ground-to-flat tabs, which was significantly different based on paired t-test (p<0.05); however, fluorescence peak was not detected in all the shade tabs. Therefore, fluorescence property of Vitapan 3D-Master shade guide should be modified to have similar fluorescence property of natural teeth and corresponding restorative materials.

Perceived color shift of a shade guide according to the change of illuminant

The perceived color of shade guide tabs is influenced by different spectral compositions of different light sources, and this can influence color matching. The purpose of this study was to determine the amount of perceived shift in color and color coordinates of a shade guide using 3 different light sources: CIE standard illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp). CIE color coordinates L*, a*, b*, chroma, and the spectral reflectance of shade tabs in a shade guide (Vitapan 3D-Master) were measured by a spectroradiometer under D65, A, and F9 simulators. Perceived color and color coordinate shifts due to the change of illuminant were determined. The influence of the type of light and shade designation of the 26 tabs on the color coordinates was analyzed by a 2-way ANOVA; correlations in the color coordinates between each corresponding pair under the 3 illuminants were determined (α=.05). All of the color coordinates were influenced by the type of illuminant and shade designation of the shade tabs (P<.001); however, each corresponding coordinate pair showed significant correlations under different illuminants (r=0.930 to 0.997, P<.01). Color differences under different illuminants were in the range of 3.1 to 9.1 ΔE units; all of these differences were perceptible (ΔE>2.6). Lightness decreased and chroma increased when the illuminant was changed from the D65 simulator to the A or F9 simulators. Perceptible shifts in the color of shade guide tabs under different ambient lighting conditions were confirmed by a spectroradiometer; these color shifts were influenced by the type of illuminant used.

Influence of the fluorescent brightener Periblanc BA on the degree of whiteness of the knitted cotton fabric

In this study the influence of the different fluorescent brightener Periblanc BA concentrations on the degree of knitted cotton fabric whiteness was investigated. Two consecutive experimental runs were performed. The first was the bleaching of the knitted cotton fabric with hydrogen peroxide using the methods of two and single bath exhaustion while the second was the optical bleaching with fluorescent brightener Periblanc BA using the exhaustion method. CIE Whiteness Index and Tint value were measured on the Color-Eye 3000 spectrophotometer at the standard illuminant D65 (Ice-Texicon, d/8, D65/10?) while K/S values were determined using the Kubelka Munk equation. The results show that cotton fabric bleached with fluorescent brightener Periblanc BA after bleaching with hydrogen peroxide using two bath exhaustion method has higher degree of whiteness (118.8) with a reddish tint in comparison to the one bleached with hydrogen peroxide using single bath method (106.1).

Optical properties of base dentin ceramics for all-ceramic restorations

Objectives The study was conducted to compare the optical parameters of VM7 ® M-shade base dentin ceramics (VITA, Germany) for all ceramic restorations to the chemical composition across the 3D-MASTER ® shade system. Methods Three disc samples, 13 mm diameter and 1.4 mm thickness, were produced for each M-shade following the manufacturer's instructions. Each disc was ground and polished to a thickness of 1.0 mm. Spectral light transmittance and reflectance data were recorded in the visible spectrum under the standard illuminant D65 and 2° observer at 10 nm intervals by using a computer-controlled spectrophotometer. Opacity, translucency and opalescence parameters were determined for each sample. Results (1) Spectral transmittance and reflectance in the short-wavelength range systematically decreased with increasing chroma number (M1, M2, M3) when compared within the same value (lightness) group. (2) Spectral transmittance and reflectance decreased systematically across the whole visible spectrum with increasing value group number when compared within the same chroma group. (3) Analysis of relationship between chemical composition and various optical parameters for all the samples showed the significant contribution of ZrO 2 and Y 2O 3 substances to optical properties of the present material. Significance Systematic variations in optical properties of VM7 ® M-shade base dentin ceramics were observed throughout the 3D-MASTER ® shade system and were suggested to be caused by the fine structure of the sample which can interfere with shorter wavelengths in the visible spectrum.