• Restorative Dentistry and Endodontics
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• v.37 no.2
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• pp.84-89
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• 2012

Objectives: This study analyzed the difference in color caused by different thickness in enamel layer of composite resins when applied with single and layering placement technique, and evaluated if the results agreed with the shade guide from the manufacturers to verify reliability of the color matching process of the manufacturers. Materials and Methods: For single composite resin samples, 6 mm diameter and 4 mm thickness cylindrical samples were fabricated using Ceram-X mono (DENTSPLY DeTrey) and CIE $L^*a^*b^*$ values were measured with spectrophotometer. Same process was done for layering composite resin samples, making 3 dentinal shade samples, 4 mm thickness, for each shade using Ceram-X duo (DENTSPLY DeTrey) and enamel shade resins were layered in 2 mm thickness and CIE $L^*a^*b^*$ values were measured. These samples were ground to 0.2 mm thickness each time, and CIE $L^*a^*b^*$ values were measured to 1 mm thickness of enamel shade resin. Results: Color difference (${\Delta}E^*$) between single and layering composite resin was 1.37 minimum and 10.53 maximum when layering thicknesses were between 1 mm and 2 mm and 6 out of 10 same shade groups suggested by manufacturer showed remarkable color difference at any thickness (${\Delta}E^*$ > 3.3). Conclusion: When using Ceram-X mono and duo for composite resin restoration, following the manufacturer's instructions for choosing the shade is not appropriate, and more accurate information for Ceram-X duo is needed on the variation and expression of the shades depending on the thickness of the enamel.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.353-358
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• 2010

Objectives: The purpose of this study was to measure the power density of light curing units transmitted through resin inlays fabricated with direct composite (Filtek Z350, Filtek Supreme XT) and indirect composite (Sinfony). Materials and Methods: A3 shade of Z350, A3B and A3E shades of Supreme XT, and A3, E3, and T1 shades of Sinfony were used to fabricate the resin inlays in 1.5 mm thickness. The power density of a halogen light curing unit (Optilux 360) and an LED light curing unit (Elipar S10) through the fabricated resin inlays was measured with a hand held dental radiometer (Cure Rite). To investigate the effect of each composite layer consisting the resin inlays on light transmission, resin specimens of each shade were fabricated in 0.5 mm thickness and power density was measured through the resin specimens. Results: The power density through the resin inlays was lowest with the Z350 A3, followed by Supreme XT A3B and A3E. The power density was highest with Sinfony A3, E3, and T1 (p < 0.05). The power density through 0.5 mm thick resin specimens was lowest with dentin shades, Sinfony A3, Z350 A3, Supreme XT A3B, followed by enamel shades, Supreme XT A3E and Sinfony E3. The power density was highest with translucent shade, Sinfony T1 (p < 0.05). Conclusions: Using indirect lab composites with dentin, enamel, and translucent shades rather than direct composites with one or two shades could be advantageous in transmitting curing lights through resin inlays.

• Restorative Dentistry and Endodontics
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• v.28 no.5
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• pp.402-408
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• 2003

This study was done to present a criterion in selection of the most proper light sources and materials by measuring metamerism index(MI) of the light curing composite resins with spectrocolorimeter. Metamerism is defined when two objects appear to be the same color in one illuminant but different in another. This is due to the fact that they have different spectral curves that fail to match under the second illuminant. In this study, A1 & A3 shade of five light curing composite resins (Esthet-X, Filteck Z250, Filteck A110. Charisma. Vitalescence) were chosen based on Vita shade. Five samples were made for shade of each product with Teflon mold (diameter: 15mm, thickness: 2mm). Metamerism index of each samples on a Barium sulfate plate($L^{*}=96.54,{\;}a^{*}=0.19,{\;}b^{*}=0.01$) prepared for sample fixation were measured with spectrocolorimeter(Miniscan XE plus. Model 4000s. Hunter Lab. USA) by applying standard light source D^{65}, C. Fcw, TL84 and A. Standardization was done with reference standard(X=80.8, Y=85.7, Z=90.8) and light trap. The results were as follows. 1. Different resins with same Vita shade showed recognizable color difference (${\delta}E^{*}>2$). 2. All composites had MI below accepted value 0.5 between standard illuminant(D$_{65}$, C, & A) and below 1.5 under fluorescent condition (Fcw & TL84). 3. MI value between $D^{65}$ and A showed higher value than MI value between other source of light(p<0.01). 4. All resins except Z250 showed MI value that A3 is higher than A1 between $D^{65}$ and A(p<0.05).except Z250 showed MI value that A3 is higher than A1 between $D^{65}$ and A(p<0.05).

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.585-603
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• 1999

Esthetic availabilities used as an esthetic restorative maternals can be determined by the optical coincidence among materials, enamel and dentin. Enamel is highly translucent. That's why esthetic materials need to correspond the close translucency of enamel. But the translucent materials are affected by the background color. So it should be predicted that the color of estorative materials depend on the any thickness and the spectral reflectance of the background on which they are placed. The object of this investigation, under above hypothesis, was to determine and analyze how they affect the final color according to the thickness, translucency and background color (white, black and dentin) fill three commercial light cured composite resins(Charisma, Spectrum TPH and Z100). And correlation was analyzed to find out the possibility of the prediction when using the certain background color and thickness of materials. Followings are the result 1. The I shade of CHA showed the lowest contrast ratio($Co_7$) while the B3 shade of Z100 showed the highest contrast ratio(p<0.05). 2. The value of $L^*$ and $b^*$ on the white and dentin background is increased with decreasing thickness. And there are significant relationships between increasing thickness and each value(R>0.085). But there is a little change of $L^*$ and $b^*$ value on the black background regardless of the thickness(p>0.05). 3. For the $a^*$ value, there was little difference in values as a function of thickness and changed irregularly regardless of thickness in all background. 4. The pattern of increasing value of $L^*$ and $b^*$ with decreasing thickness was similar to the group of white and dentin background. In both dentin one showed lesser change of value. 5. The values of $L^*a^*b^*$ measured on the different background with same thickness showed the recognizable color difference(${\Delta}E^*$>2) when the thickness was below 2.6mm. 6. Contrast ratio was increased with increasing thickness with significant relationship (R>0.9). 7. Spectral reflectance of composite resins that calculated from Kubelka-Munk equation was showed little difference compared with observed value w1th decreasing thickness.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.299-308
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• 2000

The purpose of this in vitro study was to evaluate the microleakage of 5 curing methods in class V composite restorations which are composed of two-step light curing, pulse-delay cure, low curing-light intensity, moderate curing-light intensity and high curing-light intensity. In this study, class V cavities were prepared on buccal and lingual surfaces of 50 extracted human upper or lower molars on cementum margin. Single Bond adhesive and Z-100 shade A2 were applied for each group following the manufacture's instruction. The experimental teeth were randomly divided into 5 groups of 10 samples (20 surfaces) each. Group 1: two-step light curing; Group 2: pulse-delay cure; Group 3: low curing-light intensity; Group 4: moderate curing-light intensity; Group 5: high curing-light intensity. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen was then observed with a stereomicroscope at ${\times}20$. The composite resin/tooth interfaces were examined under Scanning Electron Microscopy. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA and Dunn's Method. The results of this study were as follows. 1. In all groups, the leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. No group in this study showed significant differences in leakage values at both the enamel and the dentin margins(P<0.05). 3. In all groups, the gaps seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 4. The gaps in this study showed significant differences and two-step light-curing and low curing-light intensity produced significant less gap than high curing-light intensity(P<0.05).

• Restorative Dentistry and Endodontics
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• v.36 no.4
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• pp.324-335
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• 2011

Objectives: This study investigated the effects of the color components of light-cured composite resin before and after polymerization on degree of conversion (DC) and biaxial flexural strength (FS). Materials and Methods: Four enamel shades (A1, A2, A3, A4) and two dentin shades (A2O, A3O) of Premisa (Kerr Co.) and Denfil (Vericom Co.) were evaluated on their CIE $L^*,\;a^*,\;b^*$ color components using the spectrophotometer before curing, after curing and at 7 day. The DC of same specimens were measured with Near-infrared spectrometer (Nexus, Thermo Nicolet Co.) at 2 hr after cure and at 7 day. Finally, the FS was obtained after all the other measurements were completed at 7 day. The correlations between each color component and DC and FS were evaluated. Results: The light-curing of composite resin resulted in color changes of Premisa in red-blue direction and Denfil in green-blue direction. The DC and FS were affected by product, time and shade (3-way ANOVA, p < 0.05) and product and shade (2-way ANOVA, p < 0.05), respectively. Premisa only showed a significant correlation between the DC and CIE $a^*$ component - before and after polymerization (Pearson product moment correlation, p < 0.05). The FS of Premisa showed significant negative correlations with CIE $a^*$ and CIE $b^*$ components. Conclusions: The DC and FS of the light-curing composite resin were affected by the color components of the material before and after polymerization.

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.309-323
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• 2009

In this study we evaluated the influence of both the thickness of residual enamel and the color of the composite resins applied to lingual surface on the labial surface color. Background plates were made by randomly (A1, A2, A6D, B1, B2, B3, C1, C2, C6D) selected colors of Filtek Supreme (3M ESPE, St. Paul, U.S.A.) composite resin. Crown portion of 9 maxillary central incisors were cut off and embedded with acrylic resin except labial surface. Samples of average thickness of 2.2 mm were obtained after cutting it in a thickness of 2.5 mm from the labial surface and sandpaper polish. The shade of composite resin background was measured using Spectrophotometer ($Spectrolino^{(R)}$, GretagMacbeth, Regensdorf, Switzerland). And CIE $L^{\ast}a^{\ast}b^{\ast}$value of 2.2 mm thickness tooth samples were measured on the 9 composite resin backgrounds. And then, the cutting side of tooth samples was ground to the extent of 1.9 mm, 1.6 mm, 1.3 mm, 1.0 mm and placed on composite resin backgrounds and measured $L^{\ast}a^{\ast}b^{\ast}$values with the same method. In all samples, $L^{\ast}$value and $b^{\ast}$value seemed to have a tendency of decreasing as thickness of tooth sample becomes thinner regardless of background colors (p < 0.05). But, $a^{\ast}$value didn't show the significant differences depending on the thickness.