• Restorative Dentistry and Endodontics
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• 제9권1호
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• pp.101-106
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• 1983

It was the purpose of this study to investigate the fracture mode of dental amalgam by observing the crack propagation, and to relate this to the microstructure of the amalgam. Caulk 20th Century Regular, Caulk Spherical, Dispersalloy, and Tytin amalgam alloys were used for this study. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (Capmaster, S.S. White), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12 mm in height and was pressed by the Instron Universal Testing Machine at the speed of 1mm/min with 120Kg. The specimen removed from the mold was stored in the room temperature for a week. This specimen was polished with the emery papers from #100 to #200 and finally on the polishing cloth with 0.06${\mu}Al_2O_3$ powder suspended in water. The specimen was placed on the Instron testing machine in the method similar to the diametral tensile test and loaded at the crosshead speed of 0.05mm/min. The load was stopped short of fracture. The cracks on the polished surface of specimen was examined with scanning electron microscope (JSM-35) and analyzed by EPMA (Electron probe microanalyzer). The following results were obtained. 1. In low copper lathe-cut amalgam, the crack went through the voids and ${\gamma}_2$ phase, through the ${\gamma}_1$ phase around the ${\gamma}$ particles. 2. In low copper spherical amalgam, it was observed that the crack passed through the ${\gamma}_2$ and ${\gamma}_1$ phase, and through the boundary between the ${\gamma}_1$ and ${\gamma}$ phase. 3. In high copper dispersant (Dispersalloy) amalgam, the crack was found to propagate at the interface between the ${\gamma}_1$ matrix and reaction ring around the dispersant (Ag-Cu) particles, and to pass through the Ag-Sn particles. 4. In high copper single composition (Tytin) amalgam, the crack went through the ${\gamma}_1$ matrix between ${\eta}$ crystals, and through the unreacted alloy particle (core).

• Restorative Dentistry and Endodontics
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• 제10권1호
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• pp.153-160
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• 1984

The purpose of this study was to observe the tensile and bonding strength of the joined amalgam restoration. Amalgam alloys of fine-cut (F-type), spherical (S-type), and dispersed type (D-type) were selected in this study, and all specimens were divided into three groups according to the condensation methods as follows. Group I : the control group which condense the same kinds of mixed amalgam into the whole part of the mold respectively. Group II : the group which condense a mix of amalgam into one half of the mold, and then condense a new mix of amalgam into the rest half of the mold 15 minutes later. Group III : the group which condense a mixed amalgam into one half of the mold, and then condense a new mix of amalgam into the rest half of the mold 7 days later. All specimens were stored in incubator at $37{\pm}1^{\circ}C$ for seven days with immersing in saline solution before testing. The tensile and bonding strength of them were measured with Instron Universal Testing machine. The results were as follows: 1. In Group I, the order of tensile strength was F-type, S-type, and D-type. 2. In case of bonding of S-type + S-type, the difference of the bonding strength between Group II and III was not significant. (P> 0.05) 3. The bonding strength of F-type + S-type of Group II was marked the highest in value, and the lowest bonding strength was showed in bonded D-type + D-type of Group III. 4. In case of bonding with the different kinds of amalgam alloy in Group II, the specimen bonded to F-type was marked the highest bonding strength, and the specimen bonded with F-type was marked the lowest one. In Group II, the bonding strength of the specimens bonded with the same kinds of amalgam alloy was presented as the same order as that of Group I. 5. In Group III, the specimen connected with D-type marked the lowest bonding strength of all specimens. In Group III, the bonding strength of the specimens connected with the same kinds of amalgam alloy was the order of S-type + S-type, F-type + F-type, and D-type + D-type.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.18-32
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• 1991

The purpose of this study was to observe characteristic properties of amalgam through the polarization curves and SEM images from 4 type amalgams (Amalcap, Shofu spherical. Dispersalloy and Tytin) with 3 different surface finish procedures (polishing, burnishing and carving) by using the potentiostats (EG & GPARC) and SEM (Jeol JSM-35). After each amalgam alloy and Hg was triturated as the direction of the manufacturer by means of mechanical amalgamator (Samki), the triturated mass was inserted into the cylndrical metal mold which was 12 mm in diameter and 10 mm in height and was pressed with $100kg/cm^2$. 4 specimens of each type amalgam were burnished with egg burnisher and another 4 specimens of each type amalgam were carved with Hollenback carver. Above 8 specimens and remaining untreated 4 specimens were stored at room temperature for about 7 days. Untreated 4 specimens of each type amalgam were polished with abrasive papers (Deer) from #400 to #1200 and finally on the polishing cloth with $0.5{\mu}m$ and $0.06{\mu}m$ $Al_2O_3 $ powder suspended water. Anodic polarization measurements was employed to compare the corrosion behaviours of the amalgams in 0.9% saline solution at $37^{\circ}C$. The open circuit potential was determined after 30 minutes immersion of specimen in electrolyte. The scan rate was 1 mV/sec and the surface area of amalgam exposed to the solution was $0.64cm^2$ for each specimen. All the potentials reported are with respect to a saturated calomel electrode (SCE). SEM images of each specimen were taken after + 800 mV (SCE) polarization. The results were as follows: 1. The corrosion potential of high copper amalgam was more anodic than that of low copper amalgam. 2. The polished amalgam were more resistant to corrosion than any other burnished and carved amalgam. 3. In the case of polishing, current density of high copper amalgam was lower than that of low copper amalgam.

• 치위생과학회지
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• 제12권3호
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• pp.253-258
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• 2012

치과용 아말감은 수은, 구리, 아연, 은과 같은 여러 가지 금속으로 이루어진 합금으로 구성되었다. 아말감은 내구성과 진료 시 사용의 편리성과 경제적인 이유로 치과영역에서 가장 흔히 사용되고 효과적인 수복물질로 이용되었다. 하지만 수복물질로서의 대중성과 긴 역사에도 불구하고 아말감에 포함된 수은의 노출로부터 가져올 수 있는 잠재적 부작용 또는 합병증에 대한 염려로 논란이 계속되고 있다. 특히 어린이들의 경우 수은의 독성에 대한 위험성이 더 높기 때문에 우리는 어린이에게서 치과용 아말감과 요중 수은농도의 관련성에 대하여 알아보고자 하였다. 대도시 지역 내 두 개 초등학교 1~4학년 재학생을 대상으로 하여 구강검진과 설문조사를 시행하였으며, 구강검진 당일 채취한 소변시료를 이용하여 요중 수은농도를 분석하였다. 결과는 구강 내 아말감 충전치아가 없는 아동과 비교 했을 때 79개 이상, 10개 이상 갖는 아동의 요중 수은농도가 높아지는 상관관계가 나타났다. 결론적으로 어린이의 구강 내 아말감 충전치면수와 요중 수은농도는 관련성이 있는 것으로 사료된다.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.114-121
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• 1993

The purpose of this study was to evaluate the effect on treatment methods to shear bond strength between composite resin and amalgam when the alloy surface was finished with a diamond wheel or an sandblaster. Forty round acrylic cylinders were fabricated with a diameter of 33mm and a height of 20mm to fit into the device used during shear bond strength testing. A round undercut cavity (diameter, 8mm: depth, 2.5mm) was prepared in the center of the acrylic surface and the cavity was restored using a amalgam. A total of 40 acrylic cylinders with amalgam were divided into 4 groups according to treatment method. The group treatment were as follows : Group 1 : acid etching after finishing the amalgam with diamond wheel Group 2 : no acid etching after finishing the amalgam with diamond wheel Group 3 : acid etching after sandblasting the amalgam Group 4 : no acid etching after sandblasting the amalgam The shear bond strength of composite resin bonded to amalgam of each specimen was tested with a universal testing machine at a crosshead speed of 0.5mm/min and 500kg in full scale. The results were as follow: 1. After diamond finishing, the non-acid etching group had highest shear bond strength with 7.29kg/$cm^2$ and after sandblasting, the acidetching group had lowest shear bond strength with 4.49kg/$cm^2$. 2. In both diamond finishing and sandblasting group, acid etching of the roughened amalgam surface decreased the shear bond strength. 3. The group treated with a diamond wheel had higher shear bond strength those treated with an sandblaster but there was not significanat.

• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.199-204
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• 1989

The purpose of this study was to observe the anodic polarization curve from 4 kinds of low copper amalgam (Fine cut alloy, Spheralloy, Aristalloy and Amalcap) and 4 kinds of high copper amalgam (Dispersalloy, Sybraloy Orosphere and Tytin) obtained by using the potentiostat. The specimen made as the direction of manufacturer was stored at room temperature for about 7 days. The standard surface preparation was routinely carried out. The 0.9% saline solution was used as electrolyte in pH 6.8-7.0 at $37^{\circ}C$. The open circuit potential was determined after 30 minutes' immersion of specimen. The scan rate was 1mV/sec and the surface area of amalgam exposed to the solution was 0.785$cm^2$ for each specimen. All potentials reported are with respect to Ag/AgCl eelctrode. The following results were obtained. 1. The corrosion potential of high copper amalgams was higher than one of low copper amalgams, and the current density of high copper amalgam was lower than one of low copper amalgams. 2. The low copper amalgams had the similar pattern of polarization curve, but the high copper amalgams had the different pattern one another. 3. The polarization curve of Orosphere amalgam which is the admixed type was similar to one of low copper amalgam.

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.431-445
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• 1993

The purpose of this study was to observe corrosion characteristics of six dental amalgams and was to analyse corrosion products electrochemically. After each amalgam alloy and Hg was triturated as the direction of the manufacturer by using mechanical amalgamator, the triturated mass was inserted into the cylinderical metal mold ($12{\times}10mm$) and was condensed with 160kg/$cm^2$ by using the hydrolic press. The specimen was removed from the mold and was stored at room temperature for 1 week, and was polished with amalgam polishing kit. The anodic and cathodic polarization curve was obtained by using cyclic voltammetric method with 3-electrode potentiostat in saline for each amalgam and Ag, Sn, Cu plate specimen at $37{\pm}0.5^{\circ}C$. The potential sweep range was -1.7V~0. 4V(vs SCE) in working electrode and scan rate was 50mV/s and the exposed surface area of each specimen to the electrolytic solution was $0.79cm^2$. The results were as follows. 1. In anodic-cathodic polarization curve of amalgam specimens, two anodic current rising areas and two cathodic current peaks were obtained at the low Cu amalgam(CF, CS) specimen and three anodic current rising areas and three cathodic current peaks were obtained at the high Cu amalgam (TY, DS, HV) specimen. 2. As this compared with the anodic and cathodic current peak potentials of Sn, Cu and Ag specimen, the first cathodic current peak I c was caused by the reduction of divalent tin salt, second cathodic current peak IIIc results from the reduction of quadravalent tin salt, and third cathodic current peak me results from the reduction of copper salt. 3. As reverse potential sweeping was done repeatedly, anodic current was decreased slightly in all amalgam specimens.

• Journal of Oral Medicine and Pain
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• 제23권2호
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• pp.193-209
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• 1998

In identifying bodies that are severely decayed or damaged, methods using fingerprints and various biochemical tests are known to have its limits. To overcome this, forensic odontological method which is based on the analysis of the cranium, tooth and dental restoration is used to enhance the accuracey of individual identification. For this reason, I have come to analysis of the dental materials that exists between the teeth that is perceived to have been previously restored and the one adjacent to it. By analyzing the constituents of gold crown-restored, non-precious metal-restored, gold inlay-restored and amalgam -restored teeth, and adjacent teeth using EDX(energy dispersive X-ray microanalysis) which was invented to analyze very small amount of elements, the nature of the restoration could be predicted and the results obtained were as follows. 1. Some of constitute of gold alloy was extracted from residual cement of gold crown restoration, but that was not extracted from the restored tooth and the one adjacent to it. 2. Some of constituents of non-precious metal alloy was extracted both in the residual cement on the tooth with no-precious metal restoration and in the tooth with the restoration itself. However, none of its constituents were found in the tooth adjacent to it. 3. Some of constituents of gold alloy were found in the residual cement of gold inlay, but they were not found in the restored tooth and the adjacent tooth. 4. Some of constituents of amalgam alloy were found both in tooth restored with amalgam and in the adjacent tooth. From the results obtained above, it is possible to utilize the data obtained from analyizing residual dental materials in a more effective way. This data compensates for the lost data due to any harm done to the restorations prior to individual identification and further enhances the accuracy. Therefore, it could be concluded that this process of analyzing residual dental materials could be beneficial to individual identification in the area of forensic odontoldogy.

• 대한치과보철학회지
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• 제33권4호
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• pp.634-644
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• 1995

The purpose of this study is to evaluate the color differences in the In-Ceram according to coping thickness and various abutment core materials ; amalgam, precious alloy, composite resin, non-precious alloy. After the porcelain was built up on the In-Ceram coping at the thicknes of 0.3mm and 0.5mm then it was cemented with glass ionomer cement to the post & core materials. The following results were obtained. 1. There were significant differences in the $L^*$ values $a^*$ and $b^*$ values in the cementation of different cores, to the In-Ceram(P<0.01). $L^*$ values were not significantly different between the composite resin to the In-Ceram and the $a^*\;b^*$ values were not significantly different between the amalgam and the non-precious alloy. 2. All of cementations of In-Ceram to the core materisal had color difference(${\Delta}E^*ab$) compared to the In-Ceram. In the 0.3mm thickness of the In-Ceram copping non-precious alloy indicated the greatest value, while the composite resin core showed the lowest value with a thickness of 0.5mm In-Ceram copping. 3. By controlloing the In-Ceram coping thickness $L^*$ value was significatly different(P<0.01), but not in $a^*$ and $b^*$ values. 4. In an amalgam, precious & non-prcious alloys there was a 1,74 to 3.06 range color difference in the controlled thickness of In-Ceram coping at the thickness of 0.3mm and 0.5mm. The above results suggest that the requirement of the sufficient thickness of In-Ceram coping and the suitable core material in order to get an estheti restoration by In-Ceram and also to intercept the original core color.

• 보존과학연구
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• 통권14호
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• pp.45-76
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• 1993

Au-Cu alloyed coating layer were found by Hg-amalgam process and it seemed to be used Cu-amalgam process similar to Au-amalgam. Coated layer is dense and unique, Thickness of layer was 1.5 to $18.0\mum$ which had 95.3 to 99.8% purity of gold Matrix metal mostly cosists of forged copper alloy which had high purity and ferrite ($\alpha$) strusture. It showed excellent refining technical level at that time. Aowever, the nail, ferrous matrix used for strength needed, composed of silver foil packed and gold layer for adherence between ferrous matrix and gold layer