• 대한치과보철학회지
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• 제37권4호
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• pp.416-424
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• 1999

Simulation of naturally appearing enamel in fixed prosthodontics could be achieved with all ceramics. The purpose of this study was to investigate the stain resistance of 4 different all ceramics materials (In-ceram, IPS Empress, Celay, Vintage). Forty specimens were prepared using manifacture's instruction and the samples were divided into two groups. The specimens for one group were glazing and those for other group were ground to remove the glazing layer. All specimens were immersed in methylene-blue for 24hours. The color values for each specimen was measured with colorimeter (Mode Tc-6Fx, Tokyo Denshoku Co.) prior to and after immersion in methylene-blue. The following conclusions were drawn from this study. 1 The stain resistance of glazing ceramics was higher than that of unglazing ceramics. 2. The changes of ${\Delta}E^*$\;and\;L^*$ values were revealed in Vintage and unglazing Celay. 3. The changes of $a^*$ values were revealed in unglazing vintage, Celay, In-ceram. 4. The changes of $b^*$ value were revealed in Vintage, IPS Empress and unglazing Celay.

• 한국세라믹학회지
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• 제55권2호
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• pp.116-125
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• 2018

Color shade variation was investigated in zirconia dental blocks, prepared using commercial powders. As a reference color-shade block we used the color indexes of A2, A3.5, A4 and B3, according to the VITA classical color scale. The zirconia powders for color shade blocks showed colors of white, yellow, pink and grey, respectively, after firing at $1530^{\circ}C$. The zirconia powders were mixed according to the recipe of color shade blocks and shaped at lower pressure using a uniaxial hydrostatic press. The shaped sample was inserted into a vinyl pack and sealed in a vacuum form machine. The shaped block samples were reshaped at 450 bar using an isostatic cold press and fired at $1530^{\circ}C$ for three hours. In order to investigate the atmospheric color variation with firing temperature, the A2, A3.5, A4 and B3 sintered blocks were fired between $700^{\circ}C$ and $1300^{\circ}C$ under controlled atmosphere of $pN_2$ and $pO_2$. The surface color picture was taken using a smart phone camera and compared with the results obtained using the VITA classical color scale. Quantitative color index value, CIELAB, was measured using a color-meter. Above $800^{\circ}C$, the color darkness greatly increased with the increase of the reduction temperature and keeping time.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.417-422
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• 2016

PURPOSE. The purposes of this study were to evaluate the staining resistance of CAD/CAM resin-ceramics polished with different techniques and to determine the effectiveness of the polishing techniques on resin-ceramics, comparing it with that of a glazed glass-ceramic. MATERIALS AND METHODS. Four different CAD/CAM ceramics (feldspathic ceramic: C-CEREC Blocs, (SIRONA) and three resin-ceramics: L-Lava Ultimate, (3M ESPE), E-Enamic, (VITA) and CS-CeraSmart, (GC)) and one light cure composite resin: ME-Clearfil Majesty Esthetic (Kuraray) were used. Only C samples were glazed (gl). Other restorations were divided into four groups according to the polishing technique: nonpolished control group (c), a group polished with light cure liquid polish (Biscover LV BISCO) (bb), a group polished with ceramic polishing kit (Diapol, EVE) (cd), and a group polished with composite polishing kit (Clearfil Twist Dia, Kuraray) (kc). Glazed C samples and the polished samples were further divided into four subgroups and immersed into different solutions: distilled water, tea, coffee, and fermented black carrot juice. Eight samples ($8{\times}8{\times}1mm$) were prepared for each subgroup. According to CIELab system, four color measurements were made: before immersion, immersion after 1 day, after 1 week, and after 1 month. Data were analyzed with repeated measures of ANOVA (${\alpha}=.05$). RESULTS. The highest staining resistance was found in gl samples. There was no difference among gl, kc and cd (P>.05). Staining resistance of gl was significantly higher than that of bb (P<.05). Staining resistances of E and CS were significantly higher than those of L and ME (P<.05). CONCLUSION. Ceramic and composite polishing kits can be used for resin ceramics as a counterpart of glazing procedure used for full ceramic materials. Liquid polish has limited indications for resin ceramics.

• 한국콘텐츠학회논문지
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• 제18권2호
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• pp.290-300
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• 2018

색유리와 화장토를 이용한 새로운 기법발견의 주안점은 기존의 불편한 점을 개선해야 하기 때문인데 이는 도자기 소지와 유리의 상호물성 호환 관계에 있다. 말하자면 세로로 된 도자기 기물에는 색유리의 데코레이션 표현이 용이하나 가로로 된 기물에서는 녹아 흐르기 때문에 미적 표현이 제한을 받아왔다. 그래서 세로로 된 기물에 녹아 흐르지 않는 새로운 표현 방법의 발견이 주된 관점이다. 이를 보완한 새로운 방법은 화장토를 이용하여 색유리를 곱게 분쇄하여 희석한 후 붓으로 기벽에 칠하는 새로운 기법을 최초로 개발하였고 추가로 미적 완성도를 높이기 위해 상감기법과 귀얄기법을 적용하였다. 소성의 방법은 산화와 환원이고 소성방법에 따라 컬러가 다르게 발색 되었다. 특히 음각 된 색유리 표면을 부분부분 깎아낼 경우 독특한 붉은 갈색게열의 부드러운 그라데이션이 형성되었는데 이러한 효과를 작품 제작 뿐 아니라 산업자기에 확장 적용을 하기에도 좋을 것이다.

• 한국세라믹학회지
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• 제53권1호
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• pp.50-55
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• 2016

In order to make a highly ordered three-dimensionally macro-porous structure of zirconia ceramics, porogen precursors PMMA beads were prepared by emulsion polymerization using acrylic monomer. The monodisperse PMMA latex beads were closely packed by centrifugation as a porogen template for the infiltration of zirconium acetate solution. The mixed compound of PMMA and zirconium acetate was dried. According to the firing schedule, dry compacts of PMMA and zirconium acetate were calcined at $475^{\circ}C$ to obtain micro-, macro-, and meso- structures of polycrystalline zirconia with monodispersed porosity. Inorganic frameworks composed of $ZrO_2$ were formed and showed a three Dimensionally Ordered Microstructure [3DOM] of $ZrO_2$ ceramics. The obtained $ZrO_2$ skeleton was calcined at $710^{\circ}C$. The 3DOM $ZrO_2$ skeleton showed color tuning in solutions such as deionized [DI] $H_2O$ and/or methanol. The monodispersed crystalline micro-structure with micro/meso porosity was observed by FE-SEM.

• 대한치과보철학회지
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• 제40권6호
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• pp.572-576
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• 2002

This investigation was designed to estimate the biaxial flexure strength and fracture toughness of lithium disilicate glass-ceramics of IPS Empress 2 system pressed with as-received ingots and their sprue buttons. Two groups of the lithium disilicate glass-ceramics were prepared as follows: group 1 is ingot-pressed group; group 2 is sprue button-pressed group. A ball-on-three-ball test was used to determine biaxial flexure strength (BFS) of disks in wet environment. Scanning electron microscopy(SEM) analysis was conducted to observe the microstructure of the ceramics. Unpaired t-test showed that there were no differences in the mean biaxial Hem strength (BFS) and KIC values between group 1 and 2 (p > 0.05). Two groups showed similar values in the KIC and the strength at 5% failure probability. The SEM micrographs of the IPS Empress 2 glass-ceramic showed a closely packed, multi-directionally interlocking pattern of numerous lithium disilicate crystals protruding from the glass matrix. The lithium orthophosphate crystals could not be observed on the fracture surface etched. There was no a marked difference of the microstructure between group 1 and 2. Although there were no tests including color stability, casting accuracy, etc., the results of this study implied that we could reuse the sprue button of the pressed lithium disilicate glass-ceramic of IPS Empress 2 system.

• 한국결정성장학회지
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• 제31권2호
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• pp.84-88
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• 2021

레이저, 광학센서 등에 사용되고 있는 La2O3-CaF2-Al2O3-SiO2 계 유리에 희토류 물질을 첨가하였을 때, 열처리 온도에 따른 결정화유리의 발광 특성 변화에 대하여 연구하였다. 결정화유리를 얻기 위한 열처리 조건은 비등온 열분석을 통해 얻었으며, 열처리 온도에 따른 결정성장 정도 및 생성된 결정상 종류를 파악하기 위해 XRD 분석을 진행하였다. Scherrer's equation을 이용한 결과, 결정화유리 내부에 25~40 nm 크기의 결정들이 생성된 것으로 계산되었다. Photoluminescence (PL) 분석결과, 660~670℃에서 1시간 열처리 된 시편이 가장 우수한 PL 강도를 보였으며, CIE 색좌표계 분석결과, 열처리 유무와 관계없이 모든 결정화유리 시편들은 red-orange 빛을 발광하는 것으로 나타났다.

• 대한치과기공학회지
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• 제33권3호
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• pp.219-224
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• 2011

Purpose: The current study focused on investigating color change of dental zirconia block with respect to the block coloring time. Methods: Three types of dental zirconia blocks(Zirtooth, Pearl-HT, D-Max) were tinted with coloring agent under four different time condition (0 minutes, 1 minutes, 10 minutes, 30 minutes). The quantitative evaluation of the tinted dental zirconia blocks was conducted with spectrophotometer. Results: The Zirtooth and D-Max blocks showed lower H value. The Pearl-HT blocks showed poor reflectivity(L value). Conclusion: The study of color change of zirconia block, which consists the substructure of all ceramic Crown, is applicable for deciding appropriate coloring condition when fabricating one layer ceramic Crown or double layer ceramic Crown.

• The Journal of Advanced Prosthodontics
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• 제16권1호
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• pp.48-56
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• 2024

PURPOSE. To evaluate the metameric disparities among monolithic zirconia materials with differing yttrium compositions across various lighting conditions. MATERIALS AND METHODS. Thirty-six square-shaped zirconia samples measuring 10 × 10 × 0.5 mm were prepared from monolithic zirconia materials with three different yttrium contents. A 0.2 mm thick layer of polymerized dual-polymerizable self-adhesive resin cement was created using a silicone mold with the same dimensions as the prepared zirconia specimens. To evaluate metamerism, color measurements were conducted using a spectrophotometer device on a neutral gray background in a color measurement cabinet that offers four different illumination environments. All samples underwent aging by subjecting them to 10000 thermal cycles using a thermal cycle tester. Following thermal aging, color measurements were taken once more, and the data were recorded using the CIE L^*, a^*, b^* color system. Two-way ANOVA and Post-hoc Bonferroni tests were employed to analyze the data. RESULTS. It was observed that there was no statistical difference among the color measurements made in different illumination environments of the monolithic zirconia ceramics used to evaluate metamerism (P > .05). This observation remained consistent both before and after thermal aging. After thermal aging, the color of monolithic zirconia materials exhibited a tendency towards red and yellow hues, accompanied by a decrease in brightness levels. CONCLUSION. It can be stated that different illumination conditions did not affect the metamerism of monolithic zirconia materials, but there was a color change in monolithic zirconia materials after a thermal aging period equivalent to one year.

• 한국재료학회지
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• 제24권7호
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• pp.363-369
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• 2014

This is the study on diffusion of ceramic body oxide compounds to glaze. For ceramic bodies, no ferrous oxides contain white ware, celadon, and 3 wt% iron oxides contained white ware was used in this experiment. These ceramic bodies were glazed by transparency glaze, iron oxides contained glaze, and glaze made by pine tree ash that treated in 1240 degree, under reduction condition for an hour. An electron probe microanalyzer(EPMA) was used to study diffusion of oxides and to calculate distance of ceramics bodies. As a result, only iron oxide and magnesium oxide from the body diffused to glaze, and also made a band which shown very thin layer of iron oxide and magnesium oxide between the body and glaze. The densest band of iron oxide formed 100 to $150{\mu}m$ in the glaze, and the densest band of magnesium oxide was found 50 to $100{\mu}m$ in the glaze. Therefore, it could be concluded that iron oxide in the body is diffused to the glaze and it affects the color of glaze, even though iron oxide exists in the glaze. Furthermore, the thickness of the glaze has an effect on the color of celadon.