• Restorative Dentistry and Endodontics
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• 제25권3호
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• pp.459-473
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• 2000

Dental caries is the most common disease in the maxillofacial area. There are many factors contributing to its development, but complete understanding and prevention is not fully known. Since the structure of the coronal and root portion of the tooth is different, the remineralization and demineralization process is also known to be different. In this study, by using a partially saturated buffer solution, we created artificial enamel and dentin caries and evaluated mineral loss. A remineralization solution with four different degrees of saturation (degree of saturation ; group 1, 0.268, group 2, 0.309, group 3, 0.339, group 4, 0.390, PH 4.3, F-2ppm) was used on a demineralized specimen. The mineral precipitating quantity and depth was evaluated by using microradiography. Using an atomic force microscope (AFM), hydroxyapatite crystals of normal, demineralized, and remineralized enamel and dentin were evaluated. The results were as follows: 1. As the degree of saturation of the remineralizing solution increased, the mineral precipitation in the enamel was increased. In group 4, mineral precipitation was limited near the surface. 2. As the degree of saturation of the remineralizing solution increased, the mineral precipitation in the dentin was decreased and it occurred in a deeper portion. In group 4, however, mineral precipitation occurred on the surface and its quantity increased. 3. There was a statistically significant interaction between enamel and dentin mineral content changes on specimens treated with remineralization and demineralization solution (demineralization r=0.44, remineralization r=0.44, p<0.05). 4. Demineralized hydroxyapatite crystals showed central and peripheral dissolving and widening of intercrystal spaces under the AFM. 5. In dentin remineralization small crystal precipitation occurred between the large crystals. We conclude that by adjusting acidulated buffer solution's degree of saturation, we can control enamel and dentin remineralization. In addition, the AFM is highly useful in evaluating changes in remineralized and demineralized hydroxyapatite crystals.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.818-826
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• 1995

The present study was undertaken to investigate the crystal growth onto enamel mineral and synthetic hydroxyapatite seeds in media resembling the enamel fluid composition. Effects of fluoride at low concentrations on the precipitation were also examined in a benchtop crystal growth model adopting a miniaturized reaction column. X-ray diffraction and Fourier transform infrared spectroscopy(FTIR), as well as chemical analyses, were employed for characterization of both seed materials before and after experimentation. Remarkable findings were that (1) both biological and synthetic seeds at the same total surface areas yielded rather similar precipitation rates at all levels of fluoride concentration in solution and (2) the precipitation rate was accelerated in a manner depending on fluoride concentrations in media. FTIR differential analysis disclosed that the precipitating phase was characterized as poorly crystallized apatite, which incorporated subtle carbonate. Most of the fluoride ions in soution were readily incorporated into crystals. The overall results support the view that the seeded crystal growth model is of value to gain insight into the mechanism of enamel crystal growth under fluoride regimens.

• Restorative Dentistry and Endodontics
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• 제34권1호
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• pp.20-29
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• 2009

법랑질의 재광화에 영향을 주는 요인으로는 pH, 불소 농도, 포화도 등이 있다. 본 연구에서는 유산 완충 탈회용액을 이용하여 법랑질 시편을 인공 탈회시킨 후, pH 4.3에서 포화도를 0.22, 0.30, 0.35로 달리한 세가지 재광화 용액에 10일간 처리하여 나타나는 변화를 편광현미경으로 관찰하여 전체 탈회 깊이와 건전 표층 폭의 변화를 조사하였다. 또한 Image program (Scion Image analyzer)을 이용하여 병소 부위의 평균 mineral density를 측정하여 탈회와 재광화 후 무기질 변화량을 통해 인공 탈회된 법랑질의 동력학적 변화를 관찰하였다. 1. 재광화 후 모든 군에서 건전 표층의 폭이 증가하였는데, 포화도가 증가할수록 건전 표층 폭이 증가하였다 (P<.05). 2. 재광화 후 mineral density 변화를 관찰한 결과, 포화도가 낮은 군에서는 이온의 침착이 병소 전반적으로 일어났으나, 포화도가 높은 군에서는 건전 표층 부위와 표층하 병소의 하층부에서 이온의 침착으로 mineral density 가 증가하였고 표층하 병소의 상층부에서는 탈회가 진행되어 mineral density 가 감소하였다. 3. 재광화 후 모든 군에서 무기질량이 증가하였고 전체 탈회 깊이도 증가하였으나 각 군간에 통계적 유의차는 없었다. 본 실험에서 인공 탈회된 시편을 pH 4.3인 재광화 용액에 처리시 포화도가 높을수록 건전 표층에서 더 많은 재광화 현상이 일어났고 표층하 병소에서는 재광화 현상이 적게 일어났으며, 재광화 후 모든 군에서 전체 탈회 깊이는 증가하였다.

• 한국콘텐츠학회논문지
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• 제13권4호
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• pp.312-319
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• 2013

본 연구는 시판되는 불소양치용액과 불소치약을 4주간 적용한 다음 법랑질 재광화 효과와 화학적 성분에 미치는 영향을 표면미세경도계와 전자현미분석 (EPMA)를 이용하여 비교분석하였다. 경도측정한 결과, 0.23% 불화나트륨이 함유된 불소치약만 적용한 그룹과 0.02% 불소양치용액과 0.23% 불소치약을 병용한 그룹에서는 3주 후부터 그룹 간의 뚜렷하게 유의한 차이를 보였다 (p<0.05). 전자현미분석을 통한 치아의 주요성분인 Ca, P의 정량적인 성분분석을 시행한 결과, 불화나트륨이 함유된 불소치약만 적용한 그룹과 불소양치용액과 불소치약을 병용한 그룹에서는 유의한 차이를 보였다 (p<0.05). P 수치 변화는 모든 그룹에서 통계적으로 유의한 차이를 보이지 않았다 (p>0.05). 그러므로, 본 연구의 결과 저농도의 불소가 함유되어 있는 불소양치용액과 불소치약을 병용 처리한 경우에 칼슘 수치의 증가와 뚜렷한 표면경도의 증가를 보였음을 확인하였으며, 이는 법랑질의 재광화 효과가 있음을 확인하였다.

• 대한소아치과학회지
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• 제47권3호
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• pp.266-276
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• 2020

이 연구의 목적은 법랑질 인공우식병소에서 silver diamine fluoride (SDF)와 sodiun fluoride (NaF) 바니쉬의 재광화 효과를 비교하는 것이다. 소의 절치를 이용해 인공적으로 법랑질 초기 우식병소를 형성하고 38% SDF와 5% NaF 바니쉬를 도포한 후 인공 타액에 3주동안 보관하면서 pH-cycling을 시행하여 법랑질 표면과 3개 층의 깊이에서 micro-CT를 이용하여 무기질 밀도를 측정하고 SEM-EDS를 이용하여 법랑질 표면의 미세구조를 분석함으로써 두 제제의 재광화 효과를 비교, 평가하였다. 38% SDF군와 5% NaF 바니쉬군 모두 탈회된 법랑질의 무기질 밀도와 정상수준으로 재광화된 법랑질의 부피는 시간 경과에 따라 21일까지 지속적으로 증가하였다. 38% SDF군은 5% NaF 바니쉬군보다 법랑질의 모든 깊이와 경과한 시간대에서 무기질 밀도 증가량(△HUV) 및 정상수준으로 재광화된 법랑질의 부피 모두 컸다(p = 0.001). SEM을 이용해 관찰한 재광화된 법랑질 표면은 38% SDF군이 5% NaF 바니쉬군에 비해 더 부드러웠다. SEM 사진상에서 38% SDF를 도포한 법랑질 표면에서 은 화합물 침착이 관찰되었으며 EDS 분석에서는 은 이온이 검출되었다. 이상의 연구 결과를 종합하면 38% SDF의 법랑질 인공우식병소에서의 재광화 효과는 5% NaF 바니쉬보다 더 큼을 알 수 있었으며 이러한 결과는 앞으로 SDF가 진행된 우식의 처치에 있어서도 중요한 역할을 할 수 있을 것으로 사료된다.

• 한국치위생학회지
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• 제8권4호
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• pp.11-18
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• 2008

The purposes of this study were to examine the effect of 35% Carbamide Peroxide(CP) bleaching agent on the changes in physical and chemical characteristics of tooth. The effect of bleaching agent on enamel was analyzed using Hardness test, SEM and EDS. The microhardness between bleached groups after bleaching showed statistically significant difference according to the paired t-test. The bleached enamel surface showed apparent morphological changes compared to the enamel, which was stored in distilled water only. The difference of the total mineral contents for the distilled water and Carbamide Peroxide did not show statistical significance. These results demonstrated that bleaching using 35% Carbamide Peroxide were adversely affects application time of experimental group and may the safety of using these agents for a short time in dentist-monitored bleaching.

• Restorative Dentistry and Endodontics
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• 제12권1호
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• pp.51-64
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• 1986

The purpose of this study is to obtain the data of prestep in cavity preparation by observing changed conditions of laser irradiated dental hard tissues. The forty five extracted caries free human molars were divided into three groups and each group into five subgroups. A $CO_2$ laser irradiation was performed each subgroup of group I for one second with output power of 5 W, 10 Wand 20 W. On group II, laser irradiation was done ten times for 0.1 second duration using same power ratings as group I. On group III, laser irradiation was done 0.1 second, 0.2 second and 0.4 second with output power of 50 W. We investigated mineral contents and crater wall of obtained specimens, i.e., laser irradiated teeth, using computer controlled electron probe microanalyzer and scanning electron microscope. The following results were obtained: 1. Both calcium and phosphorus contents in laser irradiated enamel crater wall were increased, and magnesium content was decreased, but these trends were not statistically significant. 2. In laser irradiated dentin, change of mineral content was more significant. 3. In laser irradiated enamel and dentin, there were no significant differences on mineral content change due to irradiation condition and energy density. 4. In scanning electron microscopic study, enamel rods of the crater wall were fused and clefts were observed in parallel with the direction of enamel rod for all groups. 5. In laser irradiated dentin, irregular fusion and clefts were observed. In irradiated teeth with high power and short duration, the locally formed narrow crater wall was observed.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.187-194
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• 2014

Objectives: The effects of bone morphogenetic protein-2 (BMP-2) and enamel matrix derivative (EMD) respectively with mineral trioxide aggregate (MTA) on hard tissue regeneration have been investigated in previous studies. This study aimed to compare the osteogenic effects of MTA/BMP-2 and MTA/EMD treatment in MC3T3-E1 cells. Materials and Methods: MC3T3-E1 cells were treated with MTA (ProRoot, Dentsply), BMP-2 (R&D Systems), EMD (Emdogain, Straumann) separately and MTA/BMP-2 or MTA/EMD combination. Mineralization was evaluated by staining the calcium deposits with alkaline phosphatase (ALP, Sigma-Aldrich) and Alizarin red (Sigma-Aldrich). The effects on the osteoblast differentiation were evaluated by the expressions of osteogenic markers, including ALP, bone sialoprotein (BSP), osteocalcin (OCN), osteopontin (OPN) and osteonectin (OSN), as determined by reverse-transcription polymerase chain reaction analysis (RT-PCR, AccuPower PCR, Bioneer). Results: Mineralization increased in the BMP-2 and MTA/BMP-2 groups and increased to a lesser extent in the MTA/EMD group but appeared to decrease in the MTA-only group based on Alizarin red staining. ALP expression largely decreased in the EMD and MTA/EMD groups based on ALP staining. In the MTA/BMP-2 group, mRNA expression of OPN on day 3 and BSP and OCN on day 7 significantly increased. In the MTA/EMD group, OSN and OCN gene expression significantly increased on day 7, whereas ALP expression decreased on days 3 and 7 (p < 0.05). Conclusions: These results suggest the MTA/BMP-2 combination promoted more rapid differentiation in MC3T3-E1 cells than did MTA/EMD during the early mineralization period.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.560-574
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• 1997

The present study was undertaken to investigate the crystal growth onto human enamel mineral and synthetic hydroxyapatite(HA) seeds in media resembling the enamel fluid composition. Effects of fluoride at high concentrations on the precipitation were also examined in a bench-top crystal growth model adopting a miniaturized reaction column. The Ca, P and F concentrations and pH values of the inlet and outlet solutions were determined. The recovered solid samples were weighed to assess the amount of minerals precipitated during the experimental period, and finally viewed under a scanning electron microscope. Remarkable findings were that 1) both biological and synthetic seeds with the same total surface areas yielded similar amounts of crystal growth, 2) the amount of crystal growth was accelerated in a manner depending on fluoride concentrations in the media, 3) SEM observations disclosed that without the addition of fluoride, precipitation of thin, plate-like OCP crystals became prominent, but by increasing the fluoride concentration(beyond 1ppm F), rod-like crystals having a pointed edge were most frequently observed, without any evidence for precipitation of the plate-like crystals. Furthermore, the dimension of rod-like crystals was increased in proportion to fluoride concentrations, 4) there was no difference in the morphological feature of precipitated mineral phase upon seeding between human enamel seed and synthetic HA seed. The overall results support the view that the seeded crystal growth model is of value to gain insight into the mechanism of enamel crystal growth under fluoride regimens.

• 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.