• 대한치과기공학회지
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• 제17권1호
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• pp.10-25
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• 1995

The purpose of this study is to get the difference of the castability in the production of partial denture between Precious Metal Alloys and Base Metal Alloys accompanied with the frequency of reuse. As materials for an experiment, we selected Baker-444 and Soo-444 and Soo-sung as Precious Metal Alloys, New Crown and Chrome Cobalt as Base Metal Alloys. And we tired to case all of them seven times. The experimental results were as follows : 1) In the probability of segments, Baker-444 showed 100$\pm$0.00%, Soo-sung 97.24$\pm$1.58%, New Crown 95.63$\pm$4.28%, and Chrome Cobalt 91.03$\pm$7.76%. Consequently, Precious Metal Alloys were decidely superior to Base Metal Alloys in the castability. 2) In the view of the acheived result, burn-out temperature and smocking time had greatly affected the castability. 3) After casting, Precious Metal Alloys were much less than Base Metal Alloys in the quantity of consumption. It made much difference from the the compiled stastics(p<0.01)

• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.138-145
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• 2014

Cobalt-Chromium (Co-Cr) alloys are classified as predominantly base-metal alloys and are widely known for their biomedical applications in the orthopedic and dental fields. In dentistry, Co-Cr alloys are commonly used for the fabrication of metallic frameworks of removable partial dentures and recently have been used as metallic substructures for the fabrication of porcelain-fused-to-metal restorations and implant frameworks. The increased worldwide interest in utilizing Co-Cr alloys for dental applications is related to their low cost and adequate physico-mechanical properties. Additionally, among base-metal alloys, Co-Cr alloys are used more frequently in many countries to replace Nickel-Chromium (Ni-Cr) alloys. This is mainly due to the increased concern regarding the toxic effects of Ni on the human body when alloys containing Ni are exposed to the oral cavity. This review article describes dental applications, metallurgical characterization, and physico-mechanical properties of Co-Cr alloys and also addresses their clinical and laboratory behavior in relation to those properties.

• 대한치과보철학회지
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• 제37권6호
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• pp.717-729
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• 1999

Although many studies on the cytotoxicity of the dental cast base metal alloys and their components have been carried out, the results are rather conflicting because of the different type of cells used and the various experimental procedures taken. Recently a number of scientists have claimed that it would be preferable to focus on the use of cells from relevant specific location of the human bodies. Consequently, the primary cultured oral keratinocyte derived from oral mucous along with nickel chloride and several of widely used dental cast base metal alloys(two Ni-Cr alloys and one Co-Cr alloy)in domestic were selected for this study, from which 1) The amounts of released metal ions were determined using atomic absorption spectrometry, 2) The cytotoxicity of nickel chloride and dental cast base metal alloys was evaluated via MTT assay, and finally, 3) The amounts of released metal ions and the cytotoxicity of nickel chloride were correlated with the cytotoxicity of dental cast base metal alloys And, the results were summarized as follows; 1. Nickel ion from Ni-Cr alloys and Cobalt ion from Co-Cr alloys resulted in maximum releasing rate during first 2h hours, followed by a decrease in releasing rate with time. Chromium ion were found to be minimal in all alloys. 2. In cytotoxic test. with $40{\mu}M,\;80{\mu}M$ of nickel chloride, there were observed an increase in the relative cell number compared to control samples after 24 hours. With $160{\mu}M$, there was found to be no difference in the relative cell number with control, except that 48 hour showed a increase in relative cell number. With $320{\mu}M$, the relative cell number remained constant and decreased after 48 hours, and with $640{\mu}M$, a continuing decrease in relative cell number was observed throughout test period. 3 The sensitivity of primary cultured oral epithelium to nickel was lower compared to the cells used in other studies. 4. CB-80 Soft and Regalloy showed no cytotoxicity to primary cultured oral epithelium and New crown resulted in a slight cytotoxicity. In conclusion, it was shown that the primary cultured oral keratinocytes could be applied successfully as testing cells in cytotoxicity test. Futhermore, the dental cast base metal alloys used in this study were found to be biocompatible.

• 대한치과보철학회지
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• 제27권2호
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• pp.123-130
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• 1989

In order to investigate the biocompatibility of base metal alloys in dental prosthesis, the 3 types of Ni-Cr alloys and the 3 types of Co-Cr alloys were collected and each alloy was extracted in the culture medium. L-cells derived from the subcutaneous tissue of mouse and extracted medium were cultivated. The relative growth rate of L-cells in the tissue culture was calculated with N-R assay. The obtained results were as follows: 1. In the case of the Co-Cr alloys tested, its cytotoxicity proved weak. 2. In the case of the Ni-Cr alloys tested, there was no significant degree of cytotoxicity, especially 25% Victory was proved noncytotoxicity.

• 대한치과보철학회지
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• 제23권1호
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• pp.83-95
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• 1985

The purpose of this study was to evaluate microstructures on the etched surface of 11 base metal alloys for dental restorations and to observe the relationship between the etching pattern and beryllium. For this purpose, the following experiments were done; 11 base metal alloys were etched in (1) 10% $H_2SO_4$, (2) 10% $H_2SO_4$, 9 parts+methanol 1 part (3) Conc. $HNO_3$ 25%+glacial acetic acid 25%+$H_2O$ 50% (4) Conc. $HNO_3$ 5% (5) 2% glacial acetic acid added to Conc. $HNO_3$ 1% solution, with their etching conditions varied. Etched surface of alloys were examined under the scanning electron microscope. Results were as follows; 1. Almost all of Ni-Cr-Be alloys showed gooed etchd surface in $H_2SO_4$, solution, while some of those alloys which contains no beryllium showed good etched surface in $HNO_3$ solution. 2. Main components of etching solution can vary etching pattern of alloys. 3. Gamma prime phase relief, which can be found in all Ni-Cr-Be alloys, can't be found in any alloy that contains no beryllium.

• 대한치과기공학회지
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• 제11권1호
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• pp.89-93
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• 1989

The purpose of this study was to evaluate the effect of sprue length and casting pressure on the relative castability of the base metal alloys, commonly used to make porcelain metal restoration. Samples of total 30 were constucted and devided into 6 groups according to three variables (low, medium, high). The total number of complety cast squares were counted, verified and recorded. The results of this 1. main effect of casting pressure was statistically significant.(P<0.05). 2. main effect of sprue length was not statistically significant.

• 대한치과보철학회지
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• 제50권2호
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• pp.85-91
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• 2012

연구 목적: 합금의 종류와 지대주의 재질의 차이가 변연적합도에 미치는 영향을 비교 분석하고자 한다. 연구 재료 및 방법: 2개의 임플란트 유사체를 평행하게 위치시킨 후 아크릴릭 레진으로 포매하여 연구모형을 제작하였다. 바 구조물은 gold UCLA 지대주에 고귀금속 합금(high noble metal alloy)과 귀금속 합금(noble metal alloy)을, 그리고 metal UCLA 지대주에 고귀금속 합금과 비귀금속 합금(base metal alloy)을 이용하여 총 4 종류의 바 구조물을 7개씩 시편을 제작하였다. 주조된 바 구조물을 레진 모형에 장착하고 한쪽 지대나사를 조인 후, 반대쪽 임플란트-지대주 간극의 수직 거리를 앞, 뒤, 측면 3부위에서 입체 광학 현미경으로 관찰하여 기록하였다. 결과: 각 군들의 변연오차 평균값은 gold UCLA 지대주에 고귀금속 합금과 귀금속 합금을 사용했을 때 각각 $13.69{\pm}6.74{\mu}m$와 $267.26{\pm}65.85{\mu}m$이었으며, metal UCLA 지대주에 고귀금속 합금과 비귀금속 합금을 사용했을 때 $26.19{\pm}8.14{\mu}m$와 $61.90{\pm}33.65{\mu}m$이었다. One-way ANOVA를 이용하여 변연 적합도의 차이를 분석했을 때 고귀금속 함금을 사용한 군들을 제외하고, 모든 군간에 유의한 차이가 존재하였다($P$<.05). Gold UCLA 지대주-귀금속 합금 조합을 제외하고 모두 $70{\mu}m$ 이하의 수직오차를 보였다. 결론: 임플란트 바 유지 장치의 제작에 있어서 고귀금속 합금 대신 비귀금속 합금과 metal UCLA 지대주를 사용하는 것은 임상적 타당성이 있다고 판단된다.

• 대한치과기공학회지
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• 제34권4호
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• pp.337-344
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• 2012

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in $10cm^2$ and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath($37^{\circ}C$) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus$^{(R)}$alloy and SOLIBOND N$^{(R)}$alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100$^{(R)}$alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

• 대한치과보철학회지
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• 제35권1호
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• pp.103-117
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• 1997

The purpose of this experiment was to determind whether the gold electrodeposit on Pd-Ag and Ni-Cr alloys influences on the shear bond strength between veneering resin and silicoated metal surface. All the metal specimens were sandblasted with $250{\mu}m$ aluminum oxide and followed by silicoating and resin veneering. According to the metal surfaces to be veneered, experimental groups were divided into five. Group Prec : Gold alloy without gold coating Group Semi : Pd-Ag alloy without gold coating Group Base : Ni-Cr alloy without gold coating Group Semi-G : Pd-Ag alloy with gold coating Group Base-G : Ni-Cr alloy with gold coating All specimens were thermocycled 1,000 times at temperature of $5^{\circ}C$ to $55^{\circ}C$. The effects of gold electrodeposit on the shear bond strength between resin and metal interface were measured and fractured surface of the resin veneered metal was examined under the scaning electron microscope. The following results were obtained 1. The shear bond strength between resin and metal was $64.51{\pm}11.11Kg/cm^2$ in Prec group, $62.77{\pm}11.23Kg/cm^2$ in Base group and $58.97{\pm}9.20Kg/cm^2$ in Semi Group. There was no significant difference among the groups. 2. The bond strength in groups Semi-G and Base-G decreased about 17%, compared to the nongold-electrodeposit groups(Semi, Base). 3. In groups of non electrodeposit(Prec, Semi, Base), fracture occurred at the interface between alloy and resin, while fracture interface was observed between gold coating and resin in group Semi-G, and between metal substrate and gold coating in group Base-G respectively.

• Journal of Welding and Joining
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• 제15권5호
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• pp.46-55
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• 1997

This study has evaluated the liquation cracking behavior in the heat affected zone of several Ni base superalloys (Incoloy 825, Inconel 718 and Inconel 600). 304 and 310S austenitic stainless steels were also included for comparison. In addition, the mechanism of liquation cracking in the HAZ was postulated based on the extensive microstructural examinations with SEM, EDAX and TEM. The liquation cracking resistance of Ni base alloys was found to be far inferior to that of austenitic stainless steels. The liquation cracking of Incoloy 825 and Inconel 718 was believed to be closely related with the Laves-austenite(Ti rich in 825 and Nb rich in 718) and MC-austenitic eutectic phases formed along the grain boundaries by constitutional liquation and incipient melting under rapid welding thermal contraction. Further, liquation cracking resistance of the HAZ was dependent not only upon the type and amount of low melting phases but also on the grain size.