• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.148-159
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• 2003

Statement of problem Metal-ceramic restorations have been used extensively by dental clinicians for nearly 40 years. Strength an functional ability of metal-ceramic restorations are proved to be satisfying, However esthetics and biocompatibility of metal alloy which is used in metal-ceramic restoration is not ideal. Using pure gold as an alternative, have advantage of esthetics, biocompatibility over conventional metal alloy. But there had been little article which studied on the color effect of pure gold on fual porcelain color. Purpose The purpose of this study was to spectrophotometrically evaluate the difference between color of metal alloy(Au-Pt, Ni-Cr) and pure gold, during color masking procedure with opaque porcelain and to analyze the differences, Material and Methods Three types of metal - base metal(Ni-Cr), high gold alloy(Au-Pt), pure gold(GES) - specimen were fabricated 1cm in diameter. Four steps were established - after finishing, after pre-coditioning, after application of first opaque porcelain(0.08mm in thickness), after application of second opaque porcelain(0.15mm in thickness)- and tested color with spectrophotometer every each steps and analyzed with $CIEL^*a^*b^*$ color order system. One-Way ANOVA test was used to and out if there were significant differences between groups tested and Shaffe multiple comparison was used to identify where the differences were. Results 1. After finishing and pre-conditioning, pure gold(GES) group showed most high values in $L^*,a^*,b^*$. 2. After application of first opaque porcelain(0.08mm in thickness), after application of second opaque porcelain(0.15mm in thickness), pure gold(GES) group showed the least difference in $L^*,a^*,b^*$ values and the lowest ${\Delta}E$ value(${\Delta}E$=0.63). 3. After application of first opaque porcelain and after application of second opaque porcelain differences that were significant (P<0.05) between groups were found only in $a^*$ values. 4. Base metal alloy group showed the lowest $a^*$ value in test after application of first opaque porcelain and the highest value in test after application of first opaque porcelain Conclusion Pure gold group and high gold group showed higher $a^*$ values than base metal group when tested after 0.08mm thickness of opaque porcelain was applied and pure gold group showed much similar $L^*,a^*,b^*$ values between 0.08mm thickness and 0.15mm thickness of opaque porcelain. This meant that pure gold was more easily masked by opaque porcelain than the other two groups.

• Journal of Technologic Dentistry
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• v.22 no.1
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• pp.39-47
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• 2000

This study is the know the difference bond strength according to painting method of Opaque porcelain. Among Porcelain powder for Porcelain, Noritake powder, Bonding agent 1 class and metal are selected as Base metal alloy. And painting method of Opaque porcelain is divided by 4 groups : PG, WG, NG and DG. Also it is to manufacture 24 sheets of Specimen by 6 each every method and to measure Crack-initiation Strength of Metal-porcelain and it is to observe it by Scanning electron microscope. I come to get a conclusion as follows. 1. As for Debonding strength of every experiment groups, it showed that WS group which executed Wash bake had highest value, 44.25MPa and NG group which used Normal powder had value, 42.11MPa and DG group which used Bonding agent had value, 35.88MPa and PG group which used Paste opaque had value, 35.39MPa. 2. In four painting methods of Opaque porcelain, PG group, WG group, NG group and DG group, there is no significant difference statistically in Crack-initiation Strength. 3. As a result of observing fracture surface with Scanning electron microscope, it was showde that PG group remained a lot of particle of porcelain on the surface of metal than WG group, NG group and DG group.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.23-36
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• 2009

The goal of esthetic restoration is to achieve morphologic, optical, and biologic acceptance. Creation of a natural looking ceramic restoration, which blends harmoniously with surrounding dentition, is not always achieved. A successful color match is an important aspect of any esthetic dental restoration. Since natural enamel has inherent translucency, it is important that ceramic restorations reproduce the translucency and color of the natural teeth. However, the final color match of porcelain crowns to adjacent natural dentition remains some problem. Difficulties related to color matching arise from the structural differences that exist between metal ceramic crowns and natural teeth, the limited range of available ceramic shades, inadequate shade guides, different types of metal alloys, repeated firing, the condensation technique, and varying compositions of ceramic materials. Many factors contribute to the esthetic success of dental restoration: optical properties such as color and its elements of hue, value, and chroma; translucency and opacity; light transmission and scattering; and metamerism and fluorescence. The purpose of this study was to determine the color changes of metal-ceramic system with different veneering porcelain powder after repeated firing. The objectives of this in vitro study were to measure the lightness($L^*$), chromaticity($a^*$), chromaticity($b^*$), chroma($C^*$), hue(h), reflectance(%), color difference(${\Delta}E$). The following conclusions were obtained: 1. An increase in the number of firings resulted in decrease in lightness($L^*$) but increase in chromacticity($a^*$) with all porcelain. After the second sintering resulted in decrease in chromacticity($b^*$) with opaque-dentin porcelain and dentin porcelain but in increase with enamel porcelain and translucency porcelain. And after the second sintering resulted in decrease in chroma($C^*$) with opaque-dentin porcelain and dentin porcelain, but on the whole side in decrease with enamel porcelain and translucency porcelain. 2. After the second firing, a increase in the number of firings resulted in decrease reflectance(%) in all wavelength. 3. There were noticeable color differences(${\Delta}E$) between first sintering and multiple firings(dentin porcelain: 5.29~8.15, opaque-dentin porcelain: 4.83~8.2, enamel porcelain: 8.93~13.15, translucency porcelain: 9.37~12.91), but the color difference(${\Delta}E$) after second sintering were down to 4.87 in all porcelain. 4. Given the NBS Criteria, a 'trace' was not found this study but a 'slight' was found 2-3, 3-5 in dentin porcelain, 2-3 in opaque-dentin porcelain, 3-5, 5-10 in enamel porcelain and translucency porcelain, a 'noticeable' was 2-5, 3-10, 5-10 in dentin porcelain and opaque-dentin porcelain, 2-3, 2-5, 3-10 in enamel porcelain 2-3, 3-10 in translucency porcelain, an 'appreciable' was 1-2, 1-3, 2-10 in dentin porcelain 1-2, 1-3, 2-10, 3-10 in opaque-dentin porcelain, 2-10 in enamel porcelain, 2-5, 2-10 in translucency porcelain, a 'much' was 1-5, 1-10 in dentin porcelain and opaque-dentin porcelain, 1-2, 1-3, 1-5 in enamel porcelain 1-2, 1-3, 1-5, 1-10 in translucency porcelain, a 'very much' was 1-10 in enamel porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.1
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• pp.51-70
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• 1999

Dental porcelain is one of the materials of choice for restoration where esthetics is of concern, but has a considerable potentials of wear. The wear of enamel is variable when opposed by different porcelain systems and surface conditions, and the exposed dentine and opaque porcelain due to clinical failure is expected to have high potentials of wear. The purpose of this study was to investigate the wear effects of self-glazed, polished incisal porcelain. polished dentine and opaque porcelain against human enamel in the laboratory by use of a pin-on-disk type wear tester. 4 types of dental porcelain($Vita-{\Omega}$, Ceramco-II, Vintage powder $Vita-{\alpha}$ of In-Ceram system) and type IV gold alloy as cotrol group were used for test specimens. Intact buccal cusps of maxillary premolar were used for enamel specimens, and the cusp converged to a point and was devoid of visible abrasion, caries, decalcification. The upper part was the cusp of a maxillary premolar and the lower part was a porcelain specimen. The enamel wear was deter-mined by weighing the cusp before and after each test. Surface profilometer was used to quantitate wear of the porcelain specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows : 1 Self-glazed porcelain produced more enamel wear than polished porcelain, especially the enamel wear of $Vita-{\alpha}$ self-glazed porcelain was 3.2 times more than that of other groups. 2. Opaque porcelain produced least porcelain wear, $Vita-{\alpha}$ self-glazed porcelain produce greatest porcelain wear, but there was no statistically significant difference between the groups(p>0.05). 3. The enamel wear of dentine porcelain was 3.8 times more than that of polished inisal porcelain(p<0.05), and the enamel wear of opaque porcelain was 1.9 times more than that of polished inisal porcelain, but there was no statistically significant difference between the groups(p>0.05) 4. Overglazed porcelain produced less enamel wear than self-glazed porcelain, and more enamel wear than polished porcelain, but there was no statistically significant difference between the groups(P>0.05). 5. The hardness number of $Vita-{\Omega}$ dentine and Ceramco-II opaque porcelain was larger, but that of Vintage dentine and $Vita-{\alpha}$ self-glazed porcelain was similar to other groups. 6. Examination of SEM photographs revealed that overglazed porcelain had smoother surface than self-glazed porcelain, and self-glazed porcelain had smoother surface than polished porcelain. Much polishing scratches and larger porosities were observed on the opaque porcelain specimen, and much polishing scratchess and small porosities were observed on the dentine porcelain specimen.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.475-488
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• 1996

The opaque porcelain layer of porcelain-fused-to-metal(PFM) restoration is critical for the success of PFM restoration because it is the first layer placed over the treated alloy. But, the methods of opaquing technique have not been confirmed. Usually, the one layer method and two layer method have been used for the application of opaque porcelain. In the past, alloys with porcelain veneers which have been used successfully have contained various precious metals. Recent increase in the cost of precious metals stimulates considerable interest in nonprecious alloys. Although nickel-chromium alloys and nickel-chromium-beryllium alloys have been widely used, the use of cobalt-chromium alloys would be gradually increased with elimination of any potential risk of nickel-related allergic responses and/or beryllium-related toxic responses. This investigation examined one- and two-layer opaque porcelain applications to determine the effect on the bond strength of titanium added cobalt-chromium metal ceramic alloy. Bond strength of Ceramco II porcelain to titanium added cobalt-chromium alloy(2Dentitan) and gold-platinum-palladium alloy(Degudent H) were evaluated by direct shear bond strength test with Instron universal testing machine. The results were as follows; 1. When the mean shear bond strength of each experimental group were compared in $0.25cm^2$ unit area, the titanium added cobalt-chromium alloy/two layer method exhibited the greatest strength(79.7kg), followed by titanium added cobalt-chromium alloy/one layer method(76.2kg), gold-platinum-palladium alloy/two layer method(71.4kg), gold-platinum-palladium alloy/one layer method(64.2kg). 2. No significant differences in bond strength were recorded between the two opaquing techniques for gold-platinum-palladium alloy and titanium added cobalt-chromium alloy. 3. No significant differences in bond strength were recorded between the gold-platinum-palladium alloy and the titanium added cobalt-chromium alloy.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.41-54
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• 1987

The purposes of this study were to evaluate the color differences those can exist between different brands of porcelain with identical shade designation, and to find their causes. For these purposes the following experiments were executed: The color of each opaque and layered porcelain specimen was determined by spectral reflectance measurements with a spectrophotometer. The compositions of each opaque porcelain powder were analyzed by qualitative, and quantitative analysis. Microscopic structures of each opaque porcelain were observed by scanning electron microscope. The results were as follows: 1. Identical shade of different brands of porcelain produced significantly different colors. 2. Color differences among the three brands were found under different light sources. 3. Color differences among the three brands were mostly a result of differences in kinds and amounts of opacifying agents and fluxes and microstructure of porcelain systems. 4. When porcelain systems have similar compositions and firing cycles, they produced similar colors.

• The Journal of Korean Academy of Prosthodontics
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• v.20 no.1
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• pp.33-49
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• 1982

This study was undertaken to observe the porcelain porosity exerted by the contamination of the alloy and liquid. The alloy used in this study was Jelstar; liquids were Ceramco Sta-Wet liquid, distilled water and tap water; and Ceramco vacuum porcelain powder was used. The measurements with photomicroscope (x200, Olympus) were made on the porosity, the diameter (mm) of the pores and the numbers of the pores ($No/mm^2$) The results of this study were obtained as follows: 1. In the porosity, the opaque layer contained over 70% of the total porosity, and the porosity was increased about twice in every porcelain layer by the tap water. 2. The contamination of the alloy and liquid caused porosity to increase markedly at the interface of the metal-porcelain. 3. The diameter of the pores were increased about 1.5 times larger by the contaimination of the liquid, and only a slight increase in the opaque layer due to the contamination of the alloy. 4. In the numbers of the pores, there were significant differences according to the contamination of the alloy and the porcelain layer. And the contamination of the liquid caused significant differences only in the opaque layer.

• Journal of Technologic Dentistry
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• v.39 no.3
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• pp.153-159
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• 2017

Purpose: In this study, a corresponding porcelain coating material was applied to dental Co-Cr metal among PFM. Methods: The bonding strength of the fired specimens was measured by a three-point flexural rigidity test. SEM/EDS was used to observe the surface component of specimens. Results: First, All groups were higher than the minimum bonding strength of 25 MPa specified in ISO 9693 for dental metal-ceramics specimens. Second, The bonding strength of control group(WO) is 44.64 MPa. Experimental group DM was 35.45 MPa and DP was 31.82 MPa(P<0.05). Tukey's HSD tests results have shown that the bonding strength in control group(WO) is higher than that of experimental group(DM, DP). Third, In the case of metal - porcelain bonding strength, the application of opaque porcelain and firing were higher than those of the group treated with degassing process. Conclusion: The bonding strength was higher when the powder opaque porcelain was applied than the paste opaque porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.19 no.1
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• pp.61-73
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• 1981

The effects of the opaque porcelain firing temperature, the bonding agent and the degassing prior to the opaque firing On the bond strength were investigated by means of the tensile shear stIe$. The diffusional behaviours at the interface of the porcelain and the alloy, and .the microstructures of the ceramic and metal composite were studied for understanding the bonding mechanism. The results obtained in this experiment were summarizd as follow; 1. With no application of bonding agent, the tensile shear strength of the specimen firing at $1840^{\circ}F$ was higher than that of the specimen firing at $1760^{\circ}F$. 2. The highest bond strength was obtained by application of bonding agent without degassing prior to the opaque firing. 3. Application of bonding agent after the degassing showed the lowest bond strength. 4. The greater number of pores were observed at the firing temperature of $1840^{\circ}F$ than that of $1760^{\circ}F$ in the porcelain and the interface respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.195-209
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• 1991

When the porcelain fused to metal restorations were fractured at the metal interface, various techniques and materials for intraoral porcelain repair have been suggested. The purpose of this study was to investigate the effect of metal surface treatment method and water storage on the shear bond strength of four porcelain repair systems. : Clearfil(Kuraray), All-bond(Bisco), Superbond C & B(Sun Medical), Panavia OP(Kuraray). After the metal surfaces of the specimens were sandblasted by aluminum oxide or roughened by diamond point, they were stored in double deionized water(24 Hr., $37^{\circ}C$) and thermocycling was performed(24 Hr., 1024 cycles), and again half of specimes were stored in water bath(2 Months, $37^{\circ}C$). Mean shear bond strength and mode of failure were recorded. The results of this study were obtained as follows : 1. Differences were observed between the sandblasted and diamond - treated specimens in Clearfil, All-bond, and Superbond. No statistically significant differences were observed in Panavia. 2. The 2-month storage time significantly affected the bond strength of All-bond and Superbond. No statistically significant differences were observed in Clearfil and Panavia. 3. The failures were observed at the interface between opaque resin and the metal in Clearfil and All-bond. 4. The failures were observed at the interface between opaque resin and veneered resin in Panavia. The failures were observed at the interface between opaque resin and veneered resin in Superbond, but 40% of them were fractured at the interface between the metal and opaque resin after 2-month storage time.