• 대한치과보철학회:학술대회논문집
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• 2000.04a
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• pp.36-36
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• 2000

• Journal of the Korean Academy of Esthetic Dentistry
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• v.13 no.1
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• pp.41-49
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• 2004

• Journal of the Korean Academy of Esthetic Dentistry
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• v.13 no.1
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• pp.57-63
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• 2004

• 대한치과보철학회:학술대회논문집
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• 2002.04a
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• pp.75-76
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• 2002

• 대한치과보철학회:학술대회논문집
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• 2003.04a
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• pp.82-82
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• 2003

• 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.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.599-610
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• 2005

Purpose: The success of the bonding between electroformed gold and ceramic is dependent on the surface treatment of the pure gold coping. The purpose of this study was to evaluate the bonding strength between the electroformed gold and ceramic with varying surface treatment. Materials and methods: A total of 32 disks,8 were using conventional ceramometal alloy, 24 were using electroforming technique as recommended by manufacturer, were prepared. 24 electroformed disks were divided 3 groups according to surface treatment, i.e. 50 microns aluminium oxide sandblasting(GES-Sand), gold bonder treatment(GES-Bond) and $Rocatec^{TM}$ system(GES-Rocatec). For control group of conventional alloy 50 microns aluminium oxide treatment was done(V-Supragold). Energy dispersive x-ray analysis and scanning electron microscope image were observed. Using universal testing machine, shear bond strength and bonding failure mode at metal-porcelain interface were measured. Results and Conclusion: The following conclusions were drawn: 1. In the energy dispersive x-ray analysis, the Au was main component in electroformed gold(99.9wt%). After surface treatment, a little amount of $Al_2O_3(2.4wt%)$ were found in GES-Sand, and $SiO_2(4wt%)$ in GES-Bond. In GES-Rocatec, however, a large amount of $SiO_2(17.4wt%)$ were found. 2. In the scanning electron microscopy, similar pattern of surface irregu larities were observed in V-Supragold and GES-Sand. In GES-Bond, surface irregularities were increased and globular ceramic particles were observed. In GES-Rocatec, a large amount of silica particles attached to metal surface with increased surface irregularities were observed. 3. The mean shear bond strength values(MPa) in order were $22.9{\pm}3.7(V-Supragold),\;22.1{\pm}3.8(GES-Bond),\;20.1{\pm}2.8(GES-Rocatec)\;and\;13.0{\pm}1.4(GES-Sand)$. There was no significant difference between V-Supragold, GES-Bond, and GES-Rocatec. (P>0.05) 4. Most bonding failures modes were adhesive type in GES-Sand. However, in V-Supragold, GES-Bond and GES-Rocatec, cohesive and combination failures were commonly observed. From the result, with proper surface treatment method electroformed gold may have enough strength compare to conventional ceramometal alloy.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.165-173
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• 2006

Purpose: With gold electroforming system fir the double crown, the secondary crown is electroformed directly onto the primary crown. An even thick layer of high precision can be acquired. It is thought that the retention of electroformed outer crown is primarily acquired by the adhesive force (surface tension) through the saliva which is interposed between precisely fitted inner and outer crown. The purpose of this study was to investigate the effect of taper and surface area of inner crown on the retentive force of electroformed outer crown according to the presence of saliva. Materials and methods: 32 titanium inner crowns with cervical diameter of 8 mm and cone angles of 0, 2, 4, 6 degrees, which had same surface area by regulated height, were machined on a lathe. Another 32 titanium inner crowns with cone angles of 0, 2, 4, 6 degrees, which had doubled surface area by increased cervical diameter. were fabricated. Eight specimens of each group, for a total of 64 titanium inner crowns, were prepared. The electroformed outer crowns were fabricated directly on the inner crowns by using electroforming machine(GAMMAT free, Gramm Technik, Germany). The tertiary frameworks were waxed-up on the electroformed outer crown and cast using nonprecious alloy($Rexillium^(R)III,\;Jeneric^(R)/Pentronh^(R)$ Inc., USA). The cast metal frameworks were sandblasted with alubimium oxides and cemented using resin cement(Superbond C&B, Sun Medical Co., Japan) over the electroformed copings of each specimen. Then, artificial saliva($Taliva^(R)$, Halim Pharm. Co., Korea) was sprayed between the inner and outer crown, and they were connected under 5 kg force. The retentive force was measured by the universal testing machine(Tinius Olsen 1000, Tinius Olsen, USA) with a cross-head speed of 66.67 mm/sec. The direction of cross-head travel was exactly aligned with the path of removal of the respective specimens. This measurement procedures for retentive force of electroformed outer crown with artificial saliva were repeated in the same way without presence of artificial saliva. Results and Conclusion: The following conclusions were drawn: 1. The retentive force of electroformed outer crown was decreased according to increased taper of inner crown(P<.05). 2. The retentive force of electroformed outer crown showed no significant differences according to surface area and the presence of artificial saliva(P>.05).