• Restorative Dentistry and Endodontics
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• v.47 no.1
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• pp.9.1-9.11
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• 2022

Objectives: This study investigated the microhardness, flexural strength, and color stability of bleach-shade resin composites cured with 3 different light-curing units. Materials and Methods: In this in vitro experimental study, 270 samples were fabricated of bleach and A2 shades of 3 commercial resin composites (Point 4, G-aenial Anterior, and Estelite Sigma Quick). Samples (n = 5 for each trial) were cured with Bluephase N, Woodpecker LED.D, and Optilux 501 units and underwent Vickers microhardness and flexural strength tests. The samples were tested after 24 hours of storage in distilled water. Color was assessed using a spectrophotometer immediately after preparation and 24 hours after curing. Data were analyzed using 3-way analysis of variance and the Tukey test (p ≤ 0.001). Results: Samples cured with Optilux exhibited the highest and those cured with LED.D exhibited the lowest microhardness (p = 0.023). The bleach shade of Point 4 composite cured with Optilux displayed the highest flexural strength, while the same composite and shade cured with Sigma Quick exhibited the lowest (p ≤ 0.001). The color change after 24 hours was greatest for the bleach shade of G-aenial cured with Bluephase N and least for the A2 shade of Sigma Quick cured with Optilux (p ≤ 0.001). Conclusions: Light curing with polywave light-emitting diode (LED) yielded results between or statistically similar to those of quartz-tungsten-halogen and monowave LED in the microhardness and flexural strength of both A2 and bleach shades of resin composites. However, the brands of light-curing devices showed significant differences in color stability.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.443-454
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• 2008

Statement of problem: A clinically successful color match is one of the important factor to get an esthetic dental restoration. Dental shade guides are commonly used to evaluate tooth color in restorative procedure. But numerous reports have indicated that common shade guides do not provide sufficient spectral coverage of the natural tooth colors. To address issues associated with the shade guide, distinct avenues have been pursued objective spectrophotometric / colorimetric assessment. Purpose: This study compared the accuracy of tooth color selection of spectrophotometer with that of human visual determination. Three main factors were investigated, namely, the effect of light, the individual variation and the experience of the observer. Material and methods: At the first experiment, on ten patients, one operator independently selected the best matching shade to the unrestored maxillary central incisor, using a Vita Classical Shade Guide in the morning, at noon and in the afternoon. The same teeth were measured by means of a reflectance spectrophotometer. At the second experiment, on ten patients, ten operators (5 experts, 5 novices) selected and measured by the same method above at noon. At the third experiment, the results of the second experiment were divided into two groups, expert and novice, and analyzed. Results: 1. There was significant difference between visual and spectrophotometric assessment (mean ${\Delta}E$ values) in experiment 1, 2, 3 (P < .05). 2. There was no significant difference between experts and novices group, when comparing with each visual and spectrophotometric assessment (mean ${\Delta}E$ values). Conclusion: Spectrophotometer could be used to analyze the shade of natural tooth objectively. Thereby, this method offers the potential tominimize considerably the need for corrections or even remakesafter intraoral try-in of restoration. Furthermore, to achieve its advantage, both the shade-matching environment and communication between dentist and technician should be optimized with use of visual and instrumental shade-matching systems.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.356-364
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• 2007

The purpose of this study was to assess the background color-interceptive ability ana opacity of opaque shade composites (Universal composite, Filtek Z350, Charisma, Clearfil ST, Palpaque Estelite, Esthet-X, and Metafil Flo). Twenty four background specimens (diameter 5.5 mm, thickness 3.0 mm) with Root dentin Mustard (Bisco, Schaumburg, IL, USA) were made. The CIE $L^*a^*b^*$ value of background specimens was measured by a spectrophotometer (Spectrolino, GretagMacbeth, Regensdorf, Switzerland). Three specimens in every group were filled on the background specimens. The surface color of samples was measured by a spectrophotometer in 3.0 mm and every thickness to 0.5 mm while grinding. The color difference in the background color along with 3.0 mm specimen gauged the masking effect in each thickness while grinding and polishing. The opacity was calculated in 1 mm thick specimens. The opacity was in the decreasing order of Clearfil ST, Metafil Flo, Filtek Z350, Palpaque Estelite, Universal composite, Charisma, and Esthet-X (p < 0.05). As the thickness get reduced, $L^*$ value showed decreasing, $a^*$ increasing tendency. The surface color difference between pair of the 3.0 mm thick specimen and after grinding in same opaque resin was above 3.3 except Clearfil ST and Metafil Flo. The color difference (${\Delta}E^*$) between pair of background specimen and opaque resin built-up specimen showed more than 10.0 regardless kinds and thickness. The variance in opacity characteristics and color of the opaque composites is dependent upon manufacturer. When using the opaque resin, the optical properties of each material must be considered as well as cavity.

• The Journal of Advanced Prosthodontics
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• v.15 no.5
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• pp.238-247
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• 2023

PURPOSE. The purpose of this study was to assess the effect of resin cement shade on the color of different novel ultratranslucent monolithic zirconia and lithium disilicate veneer materials. MATERIALS AND METHODS. For a total of 40 specimens, flat cylindrical discs with a 9-mm diameter and 0.5-mm thickness were created using CAD/CAM technology. The specimens were divided into five groups according to their material (n = 8) (e.max, Prettau, Aidite, Shofu and Dima) using A1 shade. Resin discs with the same diameter and shade as the specimens served as tooth-colored substructures. Three shades (neutral, light and warm) of resin cement try-in pastes (Variolink Esthetic LC) were used as the luting cement material. The color of each material group was measured before and after cementation using the three cement shades, and the CIE L^*a^*b^* coordinates were obtained with a spectrophotometer. Values for the translucency parameter (TP) and color change delta E (E) before (baseline) and after cementation of each specimen were determined. To compare differences among the material groups within each shade of cement and among various shades of cement within each material, the data were analyzed using one-way ANOVA and post hoc testing. RESULTS. Color coordinates L^*, a^* and b^* significantly changed after the application of try-in pastes relative to baseline values, with a noticeable decrease in lightness (L^*) (P < .05). A significant color change (ΔE) was observed in all tested materials after cementation, with ΔE values exceeding 3.3 (P < .05). Although TP changed after cementation for most materials tested, these changes were not statistically significant (P > .05). Shofu and Dima ceramics showed the lowest TP values, while Aidite and Prettau showed the highest TP values. For e.max, translucency decreased after cementation with neutral and warm shades, and it significantly increased after cementation with a light shade. CONCLUSION. The shade of cement significantly altered the final color of the ceramic veneer material to a level above the threshold at which the clinical perception of color change occurred (> 3.3). The TP was not influenced by the cement shade. The translucency levels of the novel ultratranslucent multilayer monolithic zirconia ceramics Aidite and Prettau were higher than that of the lithium disilicate e.max material.

• Journal of Korean society of Dental Hygiene
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• v.17 no.1
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• pp.89-98
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• 2017

Objectives: The purpose of the study is to investigate the perception and satisfaction of faces and the need for aesthetic dental treatments in college students. Methods: A self-reported questionnaire was completed by 247 college students in Suncheon from August 29 to September 2, 2016. The questionnaire consisted of satisfaction of face (16 items), perception of the face (7 items), need for aesthetic dental treatment (3 items), and general characteristics of the study subjects (8 items). Tooth shade was measured using a shade guide (VITA classical shade guide, VITA North America, Chicago, USA). Data was analyzed using t test, ANOVA, and post hoc $Scheff{\acute{e}}$ test. Results: The students were satisfied with eye, mouth corner, and lip, but they were not satisfied with tooth shade, bilateral symmetry of face, and angle of jaw. The students tended to be concious of perception of others. Their most common tooth shade was orange and yellow. They preferred to have a brighter tooth color. Conclusions: To satisfy the needs of patients, it is important to understand the perception and satisfaction of face and the need for aesthetic dental treatment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.1
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• pp.110-115
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• 2004

This experiment was conducted to investigate the effect of light intensities on the growth responses, carbohydrate contents and the characteristics of leaf gas exchange in Miscanthus sinensis and Pennisetum purpurascens. The plant height and leaf length were increased to about 30% in the sun. However, those were reduced severely in the shade, and leaf necrosis was also observed. The representative growth index and the dry weight of 2 species were 50% higher than shade and the rate was reduced according to the decrease of light intensities. Total carbohydrate contents showed very similar changes to that of dry weight. However, any notable influences were observed at above the light intensities of 250~500${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ in the half shade. The size of spikes and the earliest spiking appeared in the sun and the spike color was decolorized as decreased in light intensities, irrespective of species. Photosynthetic rate of 2 species was 2 times higher in the sun than those in the shade, and it showed the typical photoresponses of sun plant. Stomatal conductances and intercelluar $CO_2$ concetration showed similar changes to that of photosynthetic rate. On the contrary, vapor pressure deficit was increased more in the shade than in the sun.

• Proceedings of the Ginseng society Conference
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• 1980.09a
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• pp.39-47
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• 1980

The harvesting and export of Canadian ginseng from the cool, shady hardwood forests of southern Canada can be traced to 1796. Because of its high dollar value and diminishing woodland supplies it was decided in 1896 that it should be cultivated under wood lath screens. Present day economics dictate changes in production techniques to allow for a decreasing supply of expensive labour. Traditional wooden lath screens have a surface area of wood of 70 per cent and permit light penetration of only about 18 per cent. Experimental woven black polypropylene shade has an estimated surface area of 72 per cent and permits light pentration of about 28 per cent. While differences in air and leaf temperatures under the two shade structures can be measured it is doubtful if these are great enough to cause differences in plant growth under the two structures. Shade grown ginseng had a low fresh and dry weight and total chlorophyll content (ratio of a to b was 3 to 1) comparable to other shade species. There was no differences in fresh and dry weight and chlorophyll content of leaves from plants grown under the two shade structures. Maximum net photosynthesis of leaves was 0.175 g $CO_2\;m^{-2}\;hr^{-1}$ and light saturation level was about $200{\mu}E\;m^{-2}\;s^{-1},$ or about 10 per cent of full sunlight.

• FLOWER RESEARCH JOURNAL
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• v.17 no.2
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• pp.75-80
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• 2009

The objective of this research was to select the native shade tolerance plant which grows well from landscape objective of the urban. Seven species native ground cover plants were evaluated on the growth and chloropyll under 0, 40, 60, 90% shading treatments. Hosta longipes was showed the quite good growth from 60% level of natural light. The plant growth of Liriope platyphylla was good within $144.2{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ intensity which is 90% shade level of natural light. But, Dryiopteris crassirhizoma was judged with shade tolerance plant which grow quite well from shading condition level of 60% degree. Carex siderosticea was showed the highest plant length and plant width in 40% shading of natural light more than at conditon too much shading. Hosta longipes, Liriope platyphylla, Dryiopteris crassirhizoma, and Carex siderosticea were as shade tolerance plant with increases chlorophyll content well to overcome a light restrictive condition and is adapted to seem with the result.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.3
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• pp.51-57
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• 1979

In order to screen the shade tolerance soybean lines, several important agronomic characters were studied after shade treatment at various growth stages. A severe influence of light reduction on agronomic characters found during the late flowering to pod filling period, and the response to shading was significantly different among the lines tested. Examining of pods number per plant after shade treatment during pod filling stage would be most effective method in the screening for shade tolerance soybean lines.

• Restorative Dentistry and Endodontics
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• v.36 no.1
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• pp.37-49
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• 2011

Objectives: The aim of this study was to evaluate the surface color of indirect resin restoration according to the layering placement of different shade of incisal composite. Materials and Methods: In this study, CIE $L^*a^*b^*$ value of 16 Body composite of Tescera ATL (Bisco, Schaumburg IL,USA) was measured by spectrophotometer (NF999, Nippon Denshuku, Japan), and compared to CIE $L^*a^*b^*$ value of Vitapan shade guide. Nine shade Incisal composite of Tescera ATL were buildup to 1 mm thickness on Body composites inlay block, and CIE $L^*a^*b^*$ value was measured. Incisal composite was ground to 0.5 mm thickness and CIE $L^*a^*b^*$ value was re-measured. Color difference between Body composite and Incisal composites layered on Body composite was calculated as a function of thickness. Results: Color difference between corresponding shade of Tescera Body composite and Vitapan shade guide was from 6.88 to 12.80. $L^*$ and $b^*$ value was decreased as layering thickness of Incisal composite on Body composite was increased. But, $a^*$ value did not show specific change tendency. Conclusions: Surface color difference between Body composites and Incisal composites layered on Body composite was increased as the layering thickness of Incisal composite increased (p < 0.05).