• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.311-320
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• 1996

If root and resection is done during surgical endodontic treatment, newly exposed dentinal tubules form pathways between the canal and the peripheral tissue. Nd : YAG laser was used to block this phenomenon, and its effect was studied with dye penetration and SEM techniques. 40 intact single rooted teeth were divided into 4 groups(10 each) : control group and test groups, in which retrograde cavity surface, cutting surface, retrograde cavity surface & cutting surface were treated with laser(1 watt 15pps) and finally retrograde filling with IRM was conducted. After that, they were stained with 2 % methylene blue, sectioned and evaluated by the maximum infiltration depth. And to observe surface change, they were prepared for SEM. The results were as follows ; 1. All experimental groups showed microleakage with variation in amount. 2. The 2nd group which treated both the retrograde cavity and cutting surface showed significantly less microleakage than the other groups(p<0.05). There was no significant difference between groups treated on one side only. 3. As a result of SEM observation of dentin surface, obstruction of dentinal tubules with marble shaped granules, which were different from normal dentin could be seen. Cracks could be seen also. 4. In summary of this experiment, it is thought that effort to obstruct the exposed dentinal tubules as well as retrograde cavity after root end resection is needed.

• 한국미생물·생명공학회지
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• 제31권1호
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• pp.90-93
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• 2003

The antibacterial activity of chitosan-alginate-Fe(II) complex (CAFC) against Escherichia coli and Staphylococcus aureus, and an opportunistic pathogen, Candida albicans, was investigated. A concentration of 1 mg/1 was needed to inhibit the growth of S. aureus and E. coli, while 100 mg/liter was sufficient for the growth inhibition of Candida albicans. The ion leakage of potassium and phosphate from E. coli cell and the penetration of ethidium bromide dye into it indicate that CAFC might be able to increase the cell permeability and consequently cellular leakage, thus leading to cell plasmolysis. Scanning electronmicroscope showed that E. coli cells treated with CAFC became irregular, swelling and expanded. In a field trial, control piglets showed average mortality of up to 60% within 3 days after the onset of diarrhea. In contrast, CAFC-treated groups without mortality was decreased to average 56% on the 1 st day after the treatment, and average 7% on the 3rd day. After then, piglets with diarrhea was not found.

• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.97-105
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• 1989

This study was conducted to evaluate and compare the apical leakage among the retrograde filling materials; retrograde filling with non-zinc amalgam, cavity varnish and non-zinc amalgam, z.o.e cement, Glass Ionomer cement, scotch bond and silux. Sixty single rooted teeth were divided into six groups and each tooth was individually prepared for its particular group. The specimens were incubated at $37^{\circ}C$ for 24 hrs and then were infiltrated by 2% methylene blue for 7 days. Apical leakage was evaluated by measuring the degree of dye penetration between the filling material and the canal wall. The results were as follows: 1. The scotch bond and silux group showed the least amount of apical leakage and the control group showed the greatest amount of apical leakage. 2. The groups retrofilled with cavity varnish and amalgam, glass-Ionomer cement, scotch bond and silux showed significantly good apical seal than control group. 3. The groups retrofilled with glass Ionomer cement, scotchbond and silux showed significantly good apical seal than the groups retrofilled with Amalgam and Zinc oxide eugenol cement.

• Restorative Dentistry and Endodontics
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• 제11권1호
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• pp.53-61
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• 1985

This study was conducted to evaluate and compare the apical leakage in the following retrograde techniques; apicoectomys, retrograde filling with zinc oxide eugenol cement, non-zinc and zinc amalgam, and cold-burnished gutta-percha method. One hundred twenty five upper anterior and lower premolar teeth were divided into five above mentioned groups and each tooth was individually prepared for its particular group. The specimens were incubated at $37^{\circ}C$ for 14 days and then were infiltrated by 2% methylene blue for 24 hours. The apical leakage was evaluated by measuring the degree of dye penetration between the filling material and the canal wall. The results were as follows: 1. The cold-burnished gutta-percha group showed the least amount of apical leakage and the apicoectomy group showed the greastest amount of apical leakage. 2. Statistics showed that there were significant differences among the groups (P<0.05), however there was no difference between the zinc oxide eugenol cement retrograde filling group and the non-zinc amalgam retrograde filling group (P>0.05).

• 한국철도학회논문집
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• 제10권1호
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• pp.39-44
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• 2007

This rafer explains a durability test of a large train car body made of carbon/epoxy composite material. The composite car body with the length of 23m was manufactured as a sandwich structure composed of an aluminum honeycomb core and CF1263 woven fabric carbon/epoxy faces. In order to evaluate durability of the composite car body, it was excited by two 500kN capacity hydraulic actuators installed underneath the body bolster. The natural frequency of the composite car body under full weight condition was found to be 4.33Hz. Based on this result, the excitation frequency and displacement of 5Hz and ${\pm}1.0mm$, respectively, were used as inputs for the durability test. The test was conducted for $2{\times}10^6$ cycles. During the test, the nondestructive tests using X-ray radiography and dye penetration method was performed to determine the presence of the cracks. Upon completion of the test, no cracks were found.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.180-193
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• 1994

The purpose of this study was to observe the sealing ability and durability of All-Bond 2, Gluma Bonding System, Scotch bond 2 and Superbond D-liner which are dentin bonding agents used as desensitizing agents. The durability of the sealing ability of the materials were compared after 0, 140, 420, 840 tooth brushing strokes. 120 extracted teeth were divided into 5 groups and the agents were applied to the exposed dentin. No agents was applied on group I, the control group. Each specimen went through thermocycling from $5^{\circ}$ to $55^{\circ}C$, 200 times. Each group was devide into 4 subgroups and artificial tooth brushing strokes were done for 0, 140, 420, 840 times. Finally the specimens were stored in 0.5 % methylene blue solution for 24 hours in a incubator set at $37^{\circ}C$. The tooth were sectioned perpendicular to the long axis and the dye penetration ratio to the pulp was measured. The following results were obtained. 1. All four dentin bonding agents initially showed excellent sealing ability. 2. All-bond 2, Gluma Bonding System and Superbond D-liner showed durability of dentinal tubule sealing effect after 840 strokes(6-week) artificial tooth brushing. 3. Scotchbond 2 showed a significant decrease in sealing ability after 420 strokes(3-week) artificial tooth brushing. (P<0.05).

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.296-303
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• 1998

The purpose of this study was to assess the effects of cavity designs on the marginal leakage of class 5 glass ionomer restorations. The five cavity designs were as follows ; notch shape(A group), notch shape with groove(B group), combined lesion(C group), combined lesion with groove and deep chamfer margin(D group) and combined lesion with groove and shoulder(E group), and each design had 10 cavities. After the cavities were restored with GIC, they were immersed in 0.5% basic fuchsin solution for 6 hours. The specimens were washed thoroughly and sectioned longitudinally in a buccolingual direction through the center of the restorations. The degree of marginal leakage was measured as the extent of dye penetration under the stereoscope. The results of this study were as follows 1. The enamel margins of all groups showed lesser leakage than dentin/cementum margins(p<0.05). 2. The combined lesion(C group) showed more leakage than notch shape(A group), but there was no siginificant difference(p>0.05). 3. In the notch shape, there was no influence on the marginal leakage by the groove preparation. 4. In the combined lesion, marginal leakage was decreased by the groove preparation and marginal modification.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.321-338
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• 1996

The purpose of this study was to evaluate the effect of moistening and air-drying of acid conditioned dentin and enamel on the marginal microleakage. In this study, Class V cavity were prepared on both buccal and lingual surface of sixty extracted human premolars with cementum margin. These specimens were randomly devided into three groups and three dentin adhesives(Scotchbond Multi-Purpose, All bond 2, Prisma Universal Bond 3) were applied to each group. The specimens in each group were subdevided into four groups (Wet/primed, Dry/primed, Wet/not primed, Dry/not primed) and the etched dentin and enamel surface were treated these four surface treatments prior to the placement of a bonding agent or adhesive. Wet/primed group was simply blot-dried with a damp facial tissue before primer placement ; Dry/primed group was air dried for 30 seconds before the placement of a primer ; Wet/not primed group and Dry/not primed group were not primed after blot dried and air dried for 30 seconds each group. The bonding agent and composite resin were applied for each group. All specimens were exposed to 500 cycle of thermal stress. Specimens were placed in a silver nitrate solution and then sectioned buccolingually through the center of the restoration. The dye penetrations of the specimens were observed with a stereo microscope. The statistical test were applied to the results using a one way analysis variance (ANOVA) and Duncan's multiple range test. The aspects of silver ion penetration into the resin/dentin interface were examined under scanning electron microscopy. The results were as follows. 1. In all groups, the enamel margin showed significantly lower leakage value than the cementum margin (p<0.05). 2. Regardless of various surface treatment and dentin adhesives, there was no significant difference at the enamel margins (p>0.05). 3. At the dentin margins, the leakage values of Dry/not primed group showed significantly higher than that of the other groups (p<0.05). The leakage values of Wet/primed group showed significantly lower than that of the other groups, but, there was no significant difference between Wet group and Dry group. 4. There was no significantly difference between the dentin adhesives regarding the surface treatments in all groups(p>0.05). 5. On the backscatterd scanning electron microscopy observation, the penetration of the silver ion occured at the bonding resin/dentin interface. In the Wet/primed group, resindentin hybrid zone and resin penetration into the dentin was observed. The resin tags were compactively formed to a thickness of $3\sim4{\mu}m$ at the upper part of dentinal tubules. In the Dry/primed group, the thickness of the hybrid zone and the diameter, depth of the resin tags diminished. In the Non-primed groups, the hybrid zone was not identified and few resin tag was observed. There was the gap formation in the resin/dentin interface.

• Restorative Dentistry and Endodontics
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• 제24권1호
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• pp.55-66
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• 1999

The purpose of this study was to evaluate the microleakage of 5 current dentin bonding systems which are composed of 2 multi-bottle systems(Scotchbond Multi-Purpose, All Bond2) and 3 one-bottle systems(Single bond, One-Step, Prime & Bond). In this in vitro study, class V cavities were prepared on buccal and lingual surfaces of sixty extracted human premolars and molars on cementum margin. The experimental teeth were randomly divided into six groups of 10 samples (20 surfaces) each, Group 1 : Scotchbond Multi-Purpose ; Group 2 : All Bond 2 ; Group 3 : Single Bond ; Group 4 : One-Step ; Group 5 : Prime & Bond ; Group 6 : no bonding agent(control). The bonding agent and composite resin were applied for each group following the manufacturer's instructions. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% Methylene blue dye for 24 hours, then rinsed with tab water. The specimen were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen were then observed with a stereomicroscope at ${\times}20$. The results of study were statistically analyzed using the Student-Newmann-Keul's Methods and the Mann-Whitney Rank Sum Test. The resin/dentin interfaces were examined under Scanning Electron Microscopy. The results of this study were as follows. 1. None of the dentin bonding systems used in this study showed significant difference in leakage values at both the enamel and the dentin margins (P>0.05). 2. In all groups except the control, leakage value seen at the enamel margin was significantly lower than that seen at the dentin margin (P<0.05). 3. Compared to the control group, all the groups treated with dentin bonding systems showed significantly lower leakage value at both enamel and dentin margins (P<0.05). 4. In the SEM view, gaps were observed in the composite resin / dentin interface in group 6 where no dentin bonding agent was used, and in all the other groups (group 1, 2, 3, 4, 5) composite resin, hybrid layer, and dentin were seen to be closely adhering to each other where there were no leakages. Well-developed resin tags 3~100${\mu}m$ in length infiltrated dentinal tubules past the hybrid layer and a hybrid layer 1~5${\mu}m$ thick had developed between the dentinal surface and the composite resin surface.

• 대한소아치과학회지
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• 제33권3호
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• pp.482-490
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• 2006

유구치의 깊은 우식으로 치수병소가 유발되어 주위 조직에 농양이 형성되는 경우를 자주 보게 된다. 특히 유구치에서 치근분지부 방사선투과성 병소를 흔히 접하게 되는데 이러한 병리적 과정에서 유구치 치근분지부 부근관은 임상적으로 매우 중요한 의미를 지닌다. 영구치의 치근분지부 부근관의 존재에 대한 연구보고는 많고 그 방법 또한 다양하였으나 유구치의 치근분지부 부근관에 대한 연구는 부족하였다. 이에 본 연구는 유구치 치근분지부 부근관의 형태적 특징과 빈도, 개통성을 이해하고자 52개의 치아를 주사형 전자현미경과 진공 흡입하에 염료를 침투시켜 다음과 같은 결과를 얻었다. 1. 주사전자현미경 연구에서 유구치 치근분지부 외면과 내면에서의 부근관의 빈도는 각각 60%, 35%였고, 부근관의 직경은 각각 $11{\sim}107{\mu}m$, $13{\sim}62{\mu}m$였다. 2. 진공 흡입 방법과 염료 침투법을 시행하여 치근분지부에 개통된 부근관을 가지는 유구치의 빈도는 20개의 시료중 50%이었다.