• Journal of dental hygiene science
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• v.14 no.1
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• pp.7-14
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• 2014

This study aims to evaluate the impact of varying exposure to dental amalgam on urinary mercury levels in children by measuring the number of amalgam-filled teeth and the variance of mercury concentration in urine over a period of 2 years. A total of 317 (male 158, female 159) elementary school children (1st~4th graders) attending 2 schools in urban regions participated in this study. At 6-month intervals, 4 oral examinations were conducted to check any variance in the conditions of dental caries and the status of dental fillings. Also, urine tests were conducted followed by a questionnaire survey. To elucidate the factors potentially affecting the mercury concentration in urine, t-test, ANOVA, chi-square test and a mixed model were used for the analysis. Regarding the status of dental fillings in line with examination time periods, deciduous teeth had more amalgam-filled surfaces than those filled with resin, whereas permanent teeth had more resin-filled surfaces than those filled with amalgam. A significant relevance was found between the exposure to dental amalgam and urinary mercury levels. Specifically, subjects whose teeth surfaces had been filled with dental amalgam showed higher urinary mercury levels than those who had no dental amalgam fillings. Based on the analysis using the mixed model, the increase in the number of teeth surfaces filled with amalgam was found to be the factor affecting the increase in urinary mercury levels. The urinary mercury levels were found to be highly associated with the exposure to dental amalgam. The more the teeth surfaces filled with amalgam, the higher the urinary mercury levels. Hence, even a trace of dental amalgam fillings can liberate mercury, affecting the variance in the urinary mercury levels. These findings suggest that some criteria or measures should be developed to minimize the exposure to dental amalgam. Moreover, relevant further studies are warranted.

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.39-49
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• 1986

The purpose of this study was to observe characteristic properties through the polarization curves and SEM images from 4 different types of amalgam obtained by using the potentiostats (Princeton EG & G) & SEM (Jeol/35), and to investigate the degree of corrosion on the oxidation peak of the each phase of amalgam. After each amalgam alloy and Hg was triturated as the direction of the manufacturer by means of the mechanical amalgamator (Shofu Co.), the triturated mass was inserted into the cylindrical metal mold which was 12mm in diameter and 10.0mm in height and was condensed by using routine manner. The specimen was removed from the mold and stored at room temperature for about 24 hours. The standard surface preparation was routinely carried out. Anodic polarization measurement was employed to confirm the corrosion behaviour of the amalgams in a 0.9% saline solution (P.H: 6.8-7.0) at $37^{\circ}C$. The initial rest potential (corrosion potential) was determined after 30 minutes of immersion of specimen in electrolyte, and the potential scan was begun at the point of 100mV cathodic from the corrosion potential. The scan rate was 0.17mV/sec. in the study to observe the degree of corrosion of each phase. SEI and EPMA images on the determined oxidation peaks of each amalgam were observed. The results were as follows: 1. In the four anodic polarization curves, low copper amalgams have three oxidation peaks and high copper amalgams have two oxidation peaks, -270mV, +26mV and +179mV(SEC) in the low copper lathe cut, and -300mV, +39mV and +163mV(SEC) in the low copper spherical. -4mV and +154mV(SEC) in the Dispersalloy, and +17mV and +180mV(SEC) in the Tytin as high copper amalgams. 2. ${\gamma}_2$ phase in the low copper amalgam and ${\eta}$ phase in the high copper amalgam were the most corrodible phases and Ag-Cu eutectic in high copper amalgam was the most slowly corroded phase. 3. Low copper amalgam was more susceptible in corrosion than high copper amalgam.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.8 no.1
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• pp.5-9
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• 1978

The purpose of this study is to investigate the effect of dental restorations on the periodontal and periapical tissues. The author examined 620 cases of amalgam, 390 cases of gold inlay, 422 cases of crown and 644 cases of bridge through the standard intraoral films being appended in the charts that had been kept at the Dept. of Oral Diagnosis in Seoul National University Hospital. This study obtained the following results; 1. The restorations of amalgam, gold inlay crown and bridge were found more frequently in female than in male. 2. The restorations of amalgam, gold inlay and crown were found more numerously in mandibular teeth than in maxillary teeth in both sexes. But in the case of crown, the fact is quite the reverse especially in anterior teeth. 3. On the contrary, in the case of bridge, the restorations of bridge were much more distributed in the maxillary teeth than in the mandibular teeth. 4. Roentgenographic changes of periodontal tissues whose teeth were treated with any type of four restorations were periodontal space widening, lamina dura discontinuity and periapical lesion in the order described in both sexes. 5. On the occasion of between amalgam and gold inlay or between crown and bridge, the differences of periodontal changes were of no consequence. On the other hand, the differences of periodontal changes were apparant between the group of amalgam & gold inlay and the group of crown & bridge.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.800-817
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• 1996

In this study, we tried to evaluate the effect of Amalgambond liner application on the degree of marginal leakage and retention of amalgam restoration by comparing with that of the Copalite and All-bond 2. The results obtained from this experiment were as follows; 1. Tensile strength representing the bond between amalgam and tooth structure was the highest in Amalgambond, and All-Bond 2, Copalite in descending order. There were statistically significant difference between each group(P<0.05). 2. The degree of microleakage in Amalgambond was lower than that of All-Bond 2, and Copalite, but no stastically significant difference could be found (P>0.05). 3. The liner such as Amalgambond or All-Bond 2 were evaluated to be superior to the conventional Copalite in bond strength as well as in microleakage. But the result of this study could not show the superiority of one material over the others; Amalgambond and All-bond 2. Besides the results of the study, other factors, such as practical convenience, should be considered in determining the selection of material. The support of welldesigned clinical studies on this subject are in demand.

• The Journal of the Korean dental association
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• v.18 no.2 s.131
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• pp.115-119
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• 1980

The purpose of this study was to observe clinical behavior on a national dispersant amalgam alloy, KISTCAP which newly developed by the KIST (Korea Instute for Science and Technology) in Korea. The results were as follows: 1. There was no significant difference in manipulating between the above mentioned alloy and the conventional lathe cut alloy. 2. The condensation pressure for this alloy was relatively less than that of conventional one. 3. More time was needed to polish the surface of this amalgam filling body than the conventional one. 4. No notable difference was seen in the over-all clinical behavior between the Whitecap and kistcap, except the latter one showed a little more tendency in redish color.

• Journal of the Korean Mathematical Society
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• v.36 no.5
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• pp.855-890
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• 1999

Necessary and sufficient conditions on the weight functions u(.) and $\upsilon$(.) are derived in order that the fractional maximal operator $M\alpha,\;0\;\leq\;\alpha\;<\;1$, is bounded from the weighted amalgam space $\ell^s(L^p(\mathbb{R},\upsilon(x)dx)$ into $\ell^r(L^q(\mathbb{R},u(x)dx)$ whenever $1\leq s\leq r<\infty\;and\;1. The boundedness problem for the fractional intergral operator $I_{\alpha},0<\alpha\leq1$, is also studied.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.8 no.1
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• pp.23-27
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• 1978

The purpose of the present investigation is to determine how frequently radiopaque zones are seen on standard intraoral films and to research some other things about radiopaque zones. This study obtained the following results: 1. According to the standard intraoral films of the charts that were kept at the Dept. of Oral Diagnosis in Seoul National University Hospital, radiopaque zones were found in the rate of 4.1% among 1150 cases of amalgam-restored teeth that were treated at least two years ago. 2. Out of teeth that possessed radiopaque zones, 38.3% had radiolucent area between amalgam restoration and radiopaque zone. 3. Out of teeth that possessed radiopaque zones, 36.2% had cement base between amalgam restoration and radiopaque zone. 4. Out of teeth that possessed radiopaque zones, no tooth had periapical radiolucency. 5. Radiopaque zones were found more frequently in the mandibular teeth than the maxillary teeth. 6. According to the result of direct x-ray taking of 50 teeth that were treated at least 2 years ago, 6% had radiopaque zone.

• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.439-442
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• 2007

A solid state Hg(Au)/HgO reference electrode was prepared utilizing gold amalgam solid particles. Solid fine powder of the gold amalgam was prepared by chemical reduction of Au(III) with NaBH4 followed by reduction of Hg(II) in the presence of gold fine particles. The solid content in the suspension of the gold amalgam particles and fine mercury oxide particles in DMF containing PVC was precipitated by the addition of a large amount of water to give solid Hg(Au)/HgO/PVC mixture. After drying, the mixture was pressure-molded to a physically stable Hg(Au)/HgO composite reference electrode material. The electrochemical characteristics of the electrode as a reference electrode were very similar to an ordinary Hg/HgO reference electrode. The electrode material can be molded and fabricated in any desired shape and size. The surface can be renewed by a simple polishing process whenever contaminated or deactivated. The applicability of the electrode in the electrochemical detection of carbohydrates after anion exchange separation was evaluated.

• The Journal of the Korean dental association
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• v.22 no.4 s.179
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• pp.323-328
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• 1984

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.499-512
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• 1994

The purpose of this study was to evaluate the microleakage electrochemically using different retrograde filling materials, different root resection angle, and different cavity preparation instruments. 104 extracted single-rooted teeth were selected for this study. 100 teeth were used as experimental groups and four was used as controls. Anatomical crowns were resected, root canals were prepared, and the apical 2 mm of roots were removed. The experimental roots were randomly divided into five equal groups. Experimental groups : Group 1. no bevel, cavity preparation with ultrasonic instruments, amalgam filling Group 2. no bevel, cavity preparation with ultrasonic instruments, SuperEBA cement filling Group 3. no bevel, cavity preparation with ultrasonic instruments, desiccated ZOE filling Group 4. $45^{\circ}$ bevel, cavity preparation with ultrasonic instruments, amalgam filling Group 5. no bevel, cavity preparation with conventional bur, amalgam filling Microleakage was measured once a day for 30 days using electrochemical method and were analyzed statistically. The results were as follows : 1. The group with Super EBA cement filling showed the least marginal leakage from second to fourth day(p<0.05), there was no significant difference between the group with amalgam filling during eighth to eighteenth day(p>0.05), but after the nineteenth day here was a higher marginal leakage than the group with amalgam filling(p<0.05). 2. The group with desiccated ZOE filling demostrated that the highest marginal leakage, started on the eighth day(p<0.05). 3. The group using ultrasonic instrument showed lower marginal leakage than the group using bur until the nineteenth day(p<0.05), but there was no significant differnce with the group using bur after twentythird day(p>0.05). 4. The group without bevel showed lower marginal leakage than the group with bevel (p<0.05). 5. Whether bevel or nor had much more effect on marginal leakage than with cavity perparation instrument when the cavity was retrogrdefilled with amalgam(stepwise regression).