• 대한소아치과학회지
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• 제24권3호
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• pp.660-677
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• 1997

The purpose of this study was to examine the morphological characteristics and combined effects of fluoride application and laser irradiation on artificial caries-like lesion formation in bovine enamel. Enamel specimens were divided into five experiment group and placed in no-treatment(group C), APF application alone(group F), laser irradiation alone(group L), APF application before laser irradiation (group FL), and APF application after laser irradiation(group LF) on artificial caries-like lesion. Sound enamel was used as a control group. The ultrastructural changes and physical effects of the fluorided and lased enamel has been investigated by using SEM, enamel solubility and microhardness test as well as distributions of calcium, phosphorus and fluoride in internal enamel by using EPMA. The following results were obtained. 1. In the all experiment groups, the amounts of dissolved calcium of enamel surfaces significantly decreased according to increasing exposure time of acid solution than control group(P<0.001). Group L showed higher than that group FL and LF in 30 and 60min(P<0.05). 2. The microhardness values of enamel surface in the control group was highest than that in the other experiment groups. Group F, L, FL and LF were significantly increased than group C(P<0.001). The enamel surface treated with APF produced deposites of numerous small globules and lased enamel showed a cracker-like appearance with microcrack and small pore. Numerous deposits were infiltrated in the fissured portion of enamel treated with APF after laser irradiation. 4. In the case of APF application alone, the elevation of the fluoride profile can be seen within $5{\mu}m$ of the outermost layer and a similar profile observed in the specimen treated with APF before laser irradiation. However, the specimen treated with APF after laser Irradiation showed a large elevation within $10{\mu}m$ of the outermost layer of the enamel. 5. The higher Ca/P ratios were observed in $10{\mu}m$ depth of lased and fluorided enamel when compared to the sound and carious enamel. The fluoride content decreased rapidly with distance from enamel surface, in the group F, fluoride concentration was significantly higher than that in the group C, L, FL, LF and control group according to increasing enamel depth (P<0.05).

• The Journal of Advanced Prosthodontics
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• 제11권1호
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• pp.23-31
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• 2019

PURPOSE. To investigate and compare the surface roughness (SR), weight and height of monolithic zirconia (MZ), ceramometal (CM), lithium disilicate glass ceramic (LD), composite resin (CR), and their antagonistic human teeth enamel. MATERIALS AND METHODS. 32 disc shaped specimens for the four test materials (n=8) and 32 premolars were prepared and randomly divided. SR, weight and height of the materials and the antagonist enamel were recorded before and after subjecting the specimens to 240,000 wear-cycles ($49N/0.8Hz/5^{\circ}C/50^{\circ}C$). SR, height, weight, and digital microscopic qualitative evaluation were measured. RESULTS. CM ($0.23+0.08{\mu}m$) and LD ($0.68+0.16{\mu}m$) exhibited the least and highest mean difference in the SR, respectively. ANOVA revealed significance (P=.001) between the materials for the SR. Paired T-Test showed significance (P<.05) for the pre- and post- SR for all the materials. For the antagonistic enamel, no significance (P=.987) was found between the groups. However, the pre- and post- SR values of all the enamel groups were significant (P<.05). Wear cycles had significant effect on enamel weight loss against all the materials (P<.05). CR and MZ showed the lowest and highest height loss of 0.14 mm and 0.46 mm, respectively. CONCLUSION. MZ and CM are more resistant to SR against the enamel than LD and CR. Enamel worn against test materials showed similar SR. Significant variations in SR values for the tested materials (MZ, LD, CM, and CR) against the enamel were found. Wear simulation significantly affected the enamel weight loss against all the materials, and enamel antagonist against MZ and CM showed more height loss.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1712-1719
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• 2015

In recent days, there was a significant development on the electrical, thermal, mechanical, physical, chemical, magnetic and optical properties of the polyamide enamel, varnish and other insulating materials by the addition of nano fillers to it. Enamel was used in High Voltage Apparatuses used in Medical Electronics as insulation. Insulating materials determine the life time of the electrical apparatuses. The life time of the insulating materials was improved by the addition of nano fillers to it. Hence the life time of the electrical apparatuses was improved by the mixing of nano fillers to the enamel. In this research, the basic dielectric properties of the enamel and enamel mixed with nano composites of silica and alumina were analyzed and compared with each other. The addition of nano fillers has improved the quality factor and capacitance of the enamel. It was also observed that the addition of nano fillers has reduced the dissipation factor and dielectric losses of the enamel. Heat produced by the dielectric losses was also reduced by adding nano fillers to it.

• 대한소아치과학회지
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• 제25권3호
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• pp.569-575
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• 1998

The purpose of this study was to evaluate the remineralization effects of fluoride-containing sealant on the artificially created enamel carious lesions. The fluoride release from the specimen of fluoride-containing sealants, the effect on enamel acid solubility and micro-hardness from the experimental sealants when applied to carious enamel surfaces were investigated. The obtained results were as follows; 1. Fluoride was a rapid rate of release during the first day, with the amount diminishing with time. The amount of fluoride released from Fuji Ionomer type III was higher than that from Teethmate-F and Helioseal-F during the 28 days of immersion(P<0.05). 2. The enamel solubility of carious enamel surface was higher than that in the Teethmate-F, Helioseal-F, and Fuji Ionomer type III (P<0.05), and there was no significant difference with Teethmate-A and Helioseal(P>0.05). 3. The microhardness value of carious enamel surface was lowest. However, there was no significant difference between the other sealants with respect to their effects on enamel hardness(P>0.05).

• 치위생과학회지
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• 제13권4호
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• pp.461-470
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• 2013

정상법랑질과 인공우식법랑질에서 불소바니쉬 도포 후의 항우식 효과를 알아보기 위하여 건전한 소의 전치를 사용하였고, 네 군으로 분류하여 실험하였다. 법랑질 표면의 재광화 및 탈회 후 결정구조의 변화를 FE-SEM으로 관찰하였고, Ca과 P의 정량적 분석은 EDS를 사용하여 측정하였다. 그 결과 불소바니쉬 도포한 경우, 재석회화로 인하여 불규칙하고 매우 거친 표면과 다공성의 구조물이 평활하고 균일한 양상으로 나타났으며, Ca 및 P의 함량이 증가되어 정상법랑질과 인공우식법랑질의 항우식 효과를 크게 증진시키는 것으로 확인되었다.

• 대한치과의사협회지
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• 제9권4호
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• pp.151-157
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• 1971

Freshly extracted permant teeth were examined by electron microscope according to the Filmy replica method. Preparatory method with hydrochloric acid or proteolytic enzyme treatment was used in order to injure the structural composition of enamel surface to compare between the natural carious defects and the etched samples used in this study. The natural carious defects were chalky white or brown discolored portions at the smooth enamel surface without having visible loss of enamel substances. The findings were as follows: 1. The first caries attact initiated from the mineralized portion of rod sheath which is located at the top of enamel rod. 2. The caries developed downward along the rod sheath interprismatic substances and enamel rods subsequently. However, the caries involvement of interprismatic substances and enamel rods occured almost at the same time. 3. The rod sheath attached to the remineralized smooth emael surface was located at the top of enamel rod.

• 대한소아치과학회지
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• 제25권1호
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• pp.209-224
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• 1998

The purpose of this study was to compare the amount of calcium fluoride deposited on the enamel and dentin surface and to obtain information on the morphological change and crystallographic details of mineral deposition after 12,000ppm APF application in vitro. The bovine enamel and dentin blocks were randomly assigned to eight groups according to artificial caries lesion formation and difference of fluoride application time. The fluoride concentration and morphological characteristics on the treated enamel and dentin surface were investigated by using fluoride quantitative analysis and SEM. The powdered enamel and dentin of the intact bovine incisors were prepared for the X-ray diffraction analysis. The following results were obtained. 1. The amounts of KOH-soluble fluoride on the carious enamel and dentin surface after 24h APF application were higher than after only 5min APF application(p<0.05), but in the case of the sound enamel and dentin surface were similar after 5min and 24h application (P>0.05). The fluoride content was highly increased in the carious dentin as compared with sound dentin after APF application(P<0.05). 2. The carious enamel surface after APF application, the demineralized enamel surface were recovered a more dense enamel surface and precipitation of crystal was observed a distintive surface layer of spherical globules of about 1 m diameter. In the case of the fluorided carious dentin surface, precipitation of calcium fluoride-like material was deposited both inside the dentinal tubules as well as in the intertubular regions. 3. The crystallographic structure of powdered enamel and dentin after 24h APF application had large crystallities of apatite and CaF2 diffraction peaks in the enamel as compared with dentin. The diffraction data collected from the 27.50-29.50(2) angular range of the powdered enamel, the (105) apatite, (225) apatite and (111) CaF2 peaks of the enamel crystallities were detected after 24h APF application.

• 한국치위생학회지
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• 제10권4호
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• pp.757-764
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• 2010

Objectives : The fluoride coating for caries prevention and strengthen enamel use NaF(sodium fluoride, Junsei Chemical Co., Ltd, Japan) 2% gel, SnF2(stannous fluoride, SIGMA-ALDRICH Gmbh, USA)8% gel and APF(acidulated phosphate fluoride, Sultan health care, USA) 1.23% gel. Methods : After put the enamel piece in these fluoride compound gel, we observed density level. And after measuring the vickers hardness, Got the following conclusions. Results : 1. After settling in the APF 1.23% during 6 days, we observed high density level of enamel surface using 250 magnification scanning microscope. The vacuum of surface packed (in) like sardines. 2. After settling in the APF 1.23% during 6 days, we observed reducing the space between the cluster of enamel surface using 50,000 magnification scanning microscope. 3. The vickers hardness change was very much on the all kinds of fluoride compound gel[2% NaF(sodium fluoride)gel, 8% SnF2(stannous fluoride) gel, 1.23% APF(acidulated phosphate fluoride)gel]. It's all because of reducing the space between the cluster of enamel surface(p<0.001). Conclusions : The vickers hardness change was very much on the all kinds of fluoride compound. It's all because of reducing the space between the cluster of enamel surface.

• KSBB Journal
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• 제29권2호
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• pp.112-117
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• 2014

The purpose of this study was to evaluate the influence of energy drinks on the erosion of dental enamel and mouse teeth growth. Exposure of enamel surface to energy drinks stimulated the release of the calcium from enamel surface of teeth. And the surface microhardness of enamel decreased after immersion in energy drinks. Enamel demineralization effects under energy drinks were observed by scanning electron microscope. Effect of maternal energy drink intake on tooth morphology of offsprings was analyzed. We concluded that the energy drinks produced a significant erosion of dental enamel.

• 한국분말재료학회지
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• 제27권5호
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• pp.388-393
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• 2020

The enamel powders used traditionally in Korea are produced by a ball-milling process. Because of their irregular shapes, enamel powders exhibit poor flowability. Therefore, polygonal enamel powders are only used for handmade cloisonné crafts. In order to industrialize or automate the process of cloisonné crafts, it is essential to control the size and shape of the powder. In this study, the flowability of the enamel powders was improved using the spheroidization process, which employs the RF plasma treatment. In addition, a simple grid structure and logo were successfully produced using the additive manufacturing process (powder bed fusion), which utilizes spherical enamel powders. The additive manufacturing technology of spherical enamel powders is expected to be widely used in the field of cloisonné crafting in the future.