Shade distribution of indirect resin composites compared with a shade guide.
ABSTRACT To determine the distributions in color parameters of two brands of indirect resin composite (belleGlass NG: 16 shades; Sinfony: 26 shades), and to compare the color of these materials with the key shade guide (Vitapan classical shade guide).
Resin composites were packed into a mold and light cured with a light-curing unit, and then were post-cured in each proprietary curing chamber. Color was measured according to the CIELAB color scale on a reflection spectrophotometer. Color distributions were evaluated based on the value-chroma scale and the CIE a*-b* scale. Color differences between each shade material and the corresponding shade tab, and between each material and the nearest shade tab, which showed the smallest color difference, in the Vitapan classical shade guide were calculated.
For both materials, the value-chroma distribution was mainly correlated with the shade groups in each material, not with the shade designations themselves. The CIE a*-b* distribution showed trends in each shade group for both materials. Compared with the Vitapan classical shade guide tabs, the range of color differences with the corresponding shade tab was 14.7-23.0 DeltaE(ab)(*) units, all of which were perceptible (DeltaE(ab)(*)>3.7).
In clinical shade matching, color distribution of each material should be considered and color discrepancy with the corresponding key shade guide tab should be also considered.
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ABSTRACT: The objectives of this study were to review the shade compatibility of esthetic restorative materials and to provide a visual method to harmonize the color of them. Published reports on the color ranges and distributions of shade guides, color differences between restorative materials and the referenced shade guides, and those between the identical shade designated restorative materials were reviewed. Several limitations in shade guides should be considered in color matching such as (1) color ranges and distributions of shade guides are different from those of human teeth, (2) arrangements of shade tabs in shade guides are not ideally logical, and (3) color of marketed esthetic restorative materials and the referenced shade tabs is significantly different. Color coordinates of restorative materials of the identical shade designations vary by the kind and brand of the restorative materials. Color differences between restorative materials and the referenced shade guides and those between the identical shade designated restorative materials are generally higher than perceptible limits. A visual color harmonization method was suggested, and the considerations for the instrumental color harmonization were provided. Visual color matching would result in color mismatching by the kind and brand of the restorative materials. The first step to improve the color matching performance would be the harmonization of the color of restorative materials with those of the corresponding shade tabs.Dental materials: official publication of the Academy of Dental Materials 12/2010; 26(12):1119-26. DOI:10.1016/j.dental.2010.08.004 · 4.16 Impact Factor
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ABSTRACT: When a corporation issues debt with a fixed nominal coupon, the real value of future payments decreases with the price level. Forward-looking corporate default decisions therefore depend on monetary policy through its impact on expected inflation. We build a general equilibrium economy with deadweight bankruptcy costs that demonstrates how nominal rigidities in corporate debt create an important role for monetary policy even in the absence of standard nominal frictions such as staggered price setting in the output market. Under a passive nominal interest rate peg, the direct effects of a negative pro- ductivity shock combine with deflation to produce strong incentives for corporate default. A debt-deflationary spiral results when there are real costs of financial distress. Inflation targeting eliminates this amplification mechanism but full inflation targeting requires permitting the nominal interest rate to depend explicitly on credit market conditions.Journal of Monetary Economics 07/2011; DOI:10.1016/j.jmoneco.2011.05.010 · 1.89 Impact Factor
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ABSTRACT: The purpose of this study was to evaluate the effect of polishing procedures on the color stability of different types of composites after aging. Forty disk-shaped specimens (Ø10×2 mm) were prepared for each composite resin type (an ormocer, a packable, a nanohybrid, and a microhybrid) for a total of 160 specimens. Each composite group was divided into four subgroups according to polishing method (n=10): control (no finishing and polishing), polishing disk, polishing wheel, and glaze material. Color parameters (L*, a*, and b*) and surface roughness were measured before and after accelerated aging. Of the polishing methods, glazed specimens showed the lowest color change (∆E*), ∆L*, and ∆b* values (p<0.05). Of the composite resins, the microhybrid composite showed the lowest ∆E* value, whereas the ormocer showed the highest (p<0.05). For all composite types, the surface roughness of their control groups decreased after aging (p<0.05). In conclusion, all composite resins showed color changes after accelerated aging, with the use of glaze material resulting in the lowest color change.Dental Materials Journal 01/2013; 32(1):58-67. DOI:10.4012/dmj.2012-045 · 0.94 Impact Factor