• 대한치과보철학회지
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• 제29권1호
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• pp.255-264
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• 1991

The purpose of this study was to evaluate the effect of the shear bond strength between porcelain laminate veneer and enamel according to the surface treatment and thermocycling. Group I, as a control group, was sandblasted only; group II was sandblasted and etched; group III was sandblasted and silane treated; and group IV was sandblasted, etched and silane treated. A porcelain block was placed onto the etched enamel under a 150g static load and the bonded site was light-cured from 4 directions for 1 minute each. The 72 bonded specimens were stored in water at $37^{\circ}C$ for 1 day. Half of each group were thermocycled at $4^{\circ}C$ and $60^{\circ}C$ for 100 cycles with a dwelling time in each bath of 1 min. Following thermocycling, the specimens were installed in an Instron universal testing machine and the shear bond strength was measured. After the specimens were fractured, the fractured surfaces were examined with SEM. The obtained results were as follows : 1. The shear bond strength of the sandblasted and etched and silane treated group(Group IV) was the strongest of all, and the shear bond strengths between the sandblasted group(Group I) and the sandblasted and silane treated group(Group III) were not statistically different(p>0.05). 2. When the shear bond strength was measured after thermocycling, only the sandblasted, etched and silane treated group(Group IV) was statistically different(p<0.05). 3. The scanning electron microscopic views of the fractured surfaces show more irregularities and more resin fragments in the etched group than in the unetched group. 4. The scanning electron microscopic views of the fractured surfaces show a more delicate surface after thermocycling and after silane treatment than before thermocycling and before silane treatment.

• 대한치과기공학회지
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• 제31권4호
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• pp.9-15
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• 2009

The purpose of this study was to observe the change of mechanical property and microstructure in porcelain fused to gold alloy by heat treatment. PFG alloys are composed with Au-Pd-Ag alloy of the additional elements with indium, tin and copper. Specimens were tested in hardness using vicker,s micro-hardness tester and the surface micro structural changes were analysed by SEM and EDS. The results were as fellows: 1. The vickers hardness showed highest in Au-Pd-Ag alloy of the additional element with tin. 2. By hardening-oxiding result, the vicker,s hardness increased in additional element with tin but there was no significant difference in additional elements with indium and copper. 3. The surface oxide layer of Au-Pd-Ag alloy with added indium and tin increased but there was small change in additional element with copper. 4. The elements of indium and tin increased with increasing heat treatment in the surface alloy.

• 대한치과기공학회지
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• 제27권1호
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• pp.97-104
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• 2005

The effect of Nb on interfacial bonding characteristics of Ni-Cr alloy for porcelain fused to metal crown (PFM) has been studied in order to investigate oxide layer. A specimens, which is 0.8mm in thickness, were fired at 1,000$^{\circ}C$ with four tests such as air, vacuum, air for 5 minutes and vacuum for 5 minutes in order to examine an oxide behavior of alloy surface generated by the adding of Nb to be controlled at a rate of 0, 1, 3 and 5. It observed oxide film form of the fired specimens with optical microscope and scanning electron microscope (SEM), and chemical formation of them with energy disperse X-ray spectroscopy (EDX). The other specimens, which is 2mm in thickness, were fired at 1,000$^{\circ}C$ with air and vacuum in order to analyze the diffusion behaviors of alloy-porcelain interface by X-ray dot mapping. The results of this study were as follows: 1. The observation of microstructure of specimens by SEM showed that the more Nb content is high, the more much intermediate compound of rich Nb is observed. 2. The surface morphology of oxide film is most dense in 3% Nb. The heat treatment in air constitutes denser oxide film than heat treatment under vacuum. 3. The diffusion behavior of oxide layer by X-ray dot mapping showed that Si, Al of porcelain diffuse toward metal.

• 대한치과기공학회지
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• 제35권4호
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• pp.271-280
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• 2013

Purpose: This study was to assess the effect of surface and heat treatment on the bond strength of veneering ceramics to zirconia. Methods: The specimens were divided into 7 groups according to surface treatment and heat treatment conditions prior to porcelain application. ten specimens from each group were subjected to a 3-point flexural test. In addition the influence of surface and heat treatment on surface roughness values and phase transformation of zirconia was evaluated. Statistical analysis was performed with one-way ANOVA and post hoc Tukey's test. Results: Bond strength ranged from $20.67{\pm}3.13MPa$ to $32.69{\pm}4.52$. Bond strength of surface treatment group was lower than that of control group but only $Al_2O_3$ sandblasting group was significant difference. Bond strength of heat treatment group was higher than that of surface treatment group but there was no statistical significance. Conclusion: Bond strength of veneering ceramics to zirconia was affected by surface and heat treatment.

• 치위생과학회지
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• 제14권2호
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• pp.140-149
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• 2014

본 연구에서는 지르코니아 에칭에 의한 표면변화가 지르코니아 코어와 도재 사이의 결합강도에 미치는 영향을 조사하기 위해 전단결합강도 실시하였고, 표면의 변화를 관찰하기 위한 SEM 측정, 에칭처리에 따른 지르코니아의 성분변화를 알아보기 위해 EDS 분석을 실시하였다. 그리고 구강상태에서 15~20년의 저온열화현상을 재현하기 위해 저온 열화 처리를 시행하여 전단결합강도 평가를 실시하여 다음과 같은 결과가 도출되었다. 1. 에칭처리를 시행하지 않은 시편과 에칭처리를 시행한 시편의 전단결합강도를 비교할 경우 에칭한 시편의 전단결합강도가 큰 것을 알 수 있다. 이는 에칭용액이 지르코니아코어 표면에 interlocking을 형성하여 기계적인 결합을 높여 주었을 것이라고 생각된다. 2. 전단결합강도의 결과(EZ>AEZ>NEZ>ANEZ)를 보았을 때 통계적으로는 유의한 차이를 보였으며, 저온열화처리를 하지 않고 에칭처리를 한 EZ군이 전단결합강도가 가장 큰 것을 알 수 있었다. 또한 파절 양상에서도 EZ군에서만 응집파절을 보여 가장 결합강도가 높다는 결과를 도출할 수 있다. 결론적으로 저온열화처리 여부에 관계없이 표면에칭처리를 한 시편의 전단결합강도가 큰 것으로 나타나 지르코니아 표면의 에칭처리로 인한 interlocking의 형성이 기계적인 결합을 향상시키는 요인이 되었다고 생각된다.

• 치위생과학회지
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• 제17권4호
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• pp.358-367
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• 2017

본 연구에서는 소성한 치과도재 시편에 대해 glazing 처리 여부에 따른 수분 침투와 기계적 물성의 비교분석을 통해 glazing 처리의 중요한 의미를 도출하고자 하였다. 또한, 제한된 가속 시효처리 방법으로 구강 내 환경에서 치과용 수복물의 내구수명 예측이 가능하였으며 수분 내에서 가속 시효처리를 통하여 치과도재는 수분 노출로 인한 열화가 일어나고 굽힘강도 저하 현상을 보였다. 치과도재의 glazing 처리를 통해 연마 시 발생하는 시편 표면의 흠집 또는 소성시 발생하는 미세균열이나 기공의 노출을 억제함으로써 굽힘강도 향상 결과를 보였다. 또한 glazing 처리한 시편이 가속 시효처리의 시간이 증가할수록 강도 저하 현상을 보이긴 하지만 glazing 처리를 하지 않은 시편과 비교하여 볼 때, 열화되는 속도가 작은 것을 알 수 있었다. 따라서 구강 내에서 치과도재 보철의 내구성을 확보하기 위해서 영구장착 전 glazing 처리를 반드시 시행할 것을 권하며, 수분 침투 억제 방법에 대해서도 향후 체계적인 연구가 되어야 할 것으로 생각한다.

• 대한치과보철학회지
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• 제35권2호
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• pp.385-399
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• 1997

The purpose of this experiment was to determine the effects of etching with a Nd : YAG Laser on dentin, or porcelain surface on the bond strength with composite resin. The dentin specimens were devided into the following 4 groups. D1 : No treatment D2 : Etched with 10% phosphoric acid D3 : Laser etchded with 1W, 20PPs D4 : Laser etched with 2W, 20PPS The procelain specimens were devided into the following 4 groups. P1 : diamond roughened P2 : etched with HF acid P3 : Laser etched with 2W, 20PPS P4 : Laser etched with 3W, 20PPS All specimens were veneered with resin. One half of the specimens were stored in $37^{\circ}C$ water for one day and the other half were thermocycled 1000 times at temperature of $5^{\circ}C\;to\;55^{\circ}C$ at 20 seconds intervals. After that, the bonding strength of composite resin to the dentin and porcelain was measured. The surface treated state and fractured state were observed with SEM. The following results were obtained. 1. In the dentin specimens, the bond strength of group D2 was highter than that of groups D1 and D3 in the case of the specimens stored in $37^{\circ}C$ water for one day, there was a statistically significant difference between group D2 and D1, D3 (P<0.05). The bonding strength of the specimens that were thermocycled decreased in the following order : group D2,D4,D3 and then D1. 2. In the porcelain specimens, the bonding strength of groups P1,P2 were higher than that of group P3 in the case of the specimens stored in $37^{\circ}C$ water for one day (P<0.05). The bonding strength of the specimens of being thermocycled decreased in the following order : group P2,P1,P4 and then P3. 3. The groups of high bond strength had a rougher surface and a high level of microporosity with SEM findings.

• 대한치과기공학회지
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• 제17권1호
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• pp.5-9
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• 1995

This study was carried out by obsorving to the conditions of an oxide on the surface of alloy according to the conditions of its heat treatment and analysing the change in composition on its surface. The result of this study is summarized as fellows. 1. It was shown that the higher the more the generated metal oxide while the higher the temperature of heat treatment. 2. The metal oxide was manily composed of Ni and Cr oxides. 3. The Ni composition indicated reduction while the higher the heat treatment in vaccum condition. 4. The Cr composition indicated increase while the higher the heat treatment in vaccum condition.

• The Journal of Advanced Prosthodontics
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• 제6권3호
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• pp.177-184
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• 2014

PURPOSE. The aim of this study was to measure the changes on the marginal and internal adaptation of zirconia based anterior fixed partial dentures after the porcelain firing process. MATERIALS AND METHODS. A total of 34 anterior fixed partial dentures using LAVA CAD/CAM system (3M ESPE, Germany) were applied. Two silicone replicas were obtained: one is obtained before porcelain firing process (initial) and the other is obtained after porcelain firing process (final), followed by the examination under a binocular stereomicroscope. Kruskal Wallis and Wilcoxon Signed Ranks tests were used for the statistical analysis (P<.05). RESULTS. No statistically significant difference was found between initial and final marginal gap values (P>.05). At the internal gap measurements, final marginal area values ($59.54{\mu}m$) were significantly lower than the initial marginal area values ($68.68{\mu}m$)(P<.05). The highest and the lowest internal gap values were observed at the incisal/occlusal area and at the marginal area, respectively. In addition, lower internal gap values were obtained for canines than for central incisors, lateral incisors and premolars at the incisal area (P<.05). CONCLUSION. The firing cycles did not affect the marginal gap of Lava CAD/CAM system, but it is controversial for the internal gap.

• 대한치과기공학회지
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• 제11권1호
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• pp.83-88
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• 1989

This investigation was performed to evaluate the effect of four different preteatment techniques on the bond strength of porcelain to non-precious metal alloy. Samples of total of 40 were divided into 4 groups according to the 4 variables which included the 50$\mu$alumina oxide air abrasion, method, the as retention bead method, the L-retention bead method, the Etching method. The completed metal-porcelain samples were compressed in Instron loading machine until gross fracture occured to examine the effect of the complex variables on the bond strength of porcelain to non precious metal alloy. The result obtained were as follows : 1. The difference of bond strength according to four different pretreatment techniques was statistically significant(p<0.01). 2. The difference of bond strength between the ss-retention bead method and the L-retention bead method was not significant statistically(p>0.05) 3. The difference of bond strength between the retention bead method and the etching method was statistically significant(p<0.01). 4. The difference of bond strength between the retention bead method and the 50$\mu$alumina oxide air abrasion method was statistically significant(p<0.01). 5. The difference of bond strength between the etching method and the 50$\mu$alumina oxide air abrasion method was statistically significant(p<0.01).