• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.470-488
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• 1996

The end products of the metabolism of the oral microorganism, organic acids, are an element that produces dental caries. Four organic acids in plaque fluid, lactic acid, acetic acid, succinic acid, propionic acid which take the important role in producing dental caries, were chosen to evaluate the effect of acid type and concentration. The subject, $100{\mu}m$ in thickness, were immersed in acid-buffer solution which has the different acid concentration of 10mM, 25mM, 50mM, 100mM and pH 4.3 and degree of saturation was $0.153{\pm}0.003$ kept in constant and were operated to produce artificial caries under different demineralization time (1, 2, 3 day) at x25. The results were obtained by observing under polarizing microscope at x25. 1. The subsurface lesion, specific finding of incipient enamel caries, showed positive birefringence. but surface zone and sound enamel showed negative birefringence. 2. The demineralization rate of enamel was increased as the acid concentration increased. 3. The subsurface lesion showed increasing depth in the order of lactic, acetic, propionic acid, succinic acid. 4. The concentration of organic acid in artificial caries system had an independent effect on demineralization rate in enamel under the constant pH and degree of saturation. The result of this study showed that not only pH and the acid strength but the concentration of organic acid had an independent effect on demineralization rate in early enamel caries. And through the further research on the factors influencing enamel demineralization, it will be necessary to develop an effective caries preventive therapy.

• Restorative Dentistry and Endodontics
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• 제24권3호
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• pp.495-502
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• 1999

Recently root caries is reported as an increasing oral disease Many researchers studied in vivo and in vitro enamel lesions but due to its peculiar structure and different chemical composition compared to the enamel, little effort has been made to root caries study. The purpose of this study is to compare and to evaluate the effect of pH on the progression of artificial root caries lesion. Under the constant degree of saturation, the specimens were divided into 4 groups(pH 4.3, 5.0, 5.5, 6.0). Each group was immersed in acid buffer solution for 1, 3, 5, 7 days and examined using the polarizing microscope. The results were as follows: 1. The body of the lesion in the dentin showed higher degree of positive birefringence compared to sound dentin. 2. The rate of progression of the lesion slowed as the pH increased. 3. In all groups, the lesion progressed rapidly at the initiation or the experiment but increased gradually as time elapsed. In conclusion, the study shows that the pH in the acid buffer solution influenced the rate of progression of the lesion in artificial root caries. Compared to the previous enamel study, the initial pattern of the lesion progressed rapidly and as time elapsed increased gradually.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.637-647
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• 1997

The purpose of this study was to evaluate the effect of concentration and pH of lactic acid on the formation of artificial root caries lesions formation in bovine teeth. The characterictics of artificially produced early root lesions were observed with polarized light microscope and the depth of lesions were mearsured with measuring microscope The results were as follows: 1. In the group of low pH and high concentration of lactic acid, the progress of lesion formation was faster than that of high pH and low concentration lactic acid group. 2. In the same group, initial lesion progress faster, but progression rate was reduced as time goes by. 3. In the development of initial root caries, cementum was act as a barrier to protect dentin from lesion progression.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.161-173
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• 1996

The cariostatic effect of fluoride had been established by many epidemiologic and experimental studies. But, there are still different views on the mechnism of cariostasis and remineralization, especially about the proper fluoride concentration. The purpose of this study is to ascertain the remineralization of caries lesion and influence of fluoride concentration which affect remineralization by a study based on dynamic mechanism. The subjects, sound permanent teeth without demineralization or crack, were immersed in lactic acid buffered demineralization solution for 4 days. Dental caries with surface zone and subsurface lesion were artificially produced. All specimens were immersed in lactic acid buffered remineralization solution which had fluoride concentrations of 1 ppm, 2 ppm, 3 ppm for 10days. Final conclusions were obtained by observing the specimens for every 10 days under polarized microscopy. 1. Remineralization of caries lesion as well as demineralization of enamel were produced by changing the degree of saturation of lactic acid buffer solution. 2. Remineralization of caries lesion was facillitated by fluoride ion in lactic acid buffer solution. but, remineralization of the entire caries lesion was not increased as fluoride ion concentration increased.

• 한국융합학회논문지
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• 제7권6호
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• pp.133-139
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• 2016

본 연구는 최근 새롭게 개발된 fTCP와 현재 치과임상에서 재광화 크림으로 널리 사용되고 있는 CPP-ACP의 재광화 효과를 비교하기 위하여 QLF-D를 이용하여 인공우식병소에서 fTCP와 CPP-ACP의 무기질소실 변화를 평가하고자 하였다. 실험에 사용된 우치시편은 탈회용액에 10일간 보관하여 인공우식병소를 형성하였고, 무작위로 두 군으로 분류하였다. 1군은 10% CPP-ACP가 포함된 Tooth Mousse 군이고, 2군은 fTCP가 포함된 Clinpro Tooth Creme군이다. 두 종류의 치아크림을 각각 탈회병소에 바르고 1주일간 인공타액에 침전 후 QLF-D를 이용하여 병소의 형광소실량(${\Delta}F$)을 평가하였다. QLF-D 분석결과 Tooth Mousse군은 처치 후에 ${\Delta}F$값과 ${\Delta}Fmax$값이 각각2.65, 6.63 증가하여 무기질 소실이 통계적으로 유의하게 감소(p<0.05)한 반면, Clinpro Tooth Creme군은 통계적으로 유의한 차이가 없었다. 또한 ${\Delta}Fmax$값에서는 처치 후 Tooth Mousse군이 Clinpro Tooth Creme군에 비해 통계적으로 유의하게 감소하였다(p<0.05). 그러므로 10% CPP-ACP가 포함된 Tooth Mousse는 fTCP가 포함된 Clinpro Tooth Creme보다 초기우식병소의 재광화 치료에 더욱 효과적이다.

• 대한소아치과학회지
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• 제46권2호
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• pp.190-199
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• 2019

인공우식 유발 용액 제조 방법 중의 하나인 White의 방법에 사용되는 $Carbopol^{(R)}$ 907의 생산이 최근 중단되면서, 그동안 사용되어 왔던 $Carbopol^{(R)}$ 907을 대체할 새로운 법랑질 보호제가 요구되게 되었다. 기존 White의 방법에 따라 $Carbopol^{(R)}$ 907을 사용하여 제조하고, 같은 방법으로 $Carbopol^{(R)}$ 2050을 사용하여 인공 탈회 용액을 제조한 후, 1일부터 20일까지 법랑질 표면에 인공우식을 유발시키고 편광현미경으로 관찰하여 병소 깊이의 변화와 우식 양상을 평가하였다. 편광 현미경 소견을 관찰한 결과, $Carbopol^{(R)}$ 907과 $Carbopol^{(R)}$ 2050을 사용한 탈회 용액으로 유발된 인공 우식은 자연 발생의 치아우식증과 매우 유사한 소견을 보였다. $Carbopol^{(R)}$ 907과 $Carbopol^{(R)}$ 2050을 사용한 탈회 용액으로 인공 우식을 유발한 영구치 법랑질 병소의 탈회 기간 경과에 따른 병소 깊이를 회귀 분석한 결과, $Carbopol^{(R)}$ 907을 사용한 경우는 회귀식이 Y = 8.4X - 0.4이었고, $Carbopol^{(R)}$ 2050을 사용한 경우는 회귀식이 Y = 9.8X + 8.0이었다. $Carbopol^{(R)}$ 907을 사용한 경우에 대한 회귀식의 R square 값은 0.945이었고, $Carbopol^{(R)}$ 2050을 사용한 경우는 R square 값이 0.965로 나타났다. 초기 법랑질 우식 병소 연구에 있어 인공 우식 유발 용액 제조시에 $Carbopol^{(R)}$ 2050을 사용한 경우가 $Carbopol^{(R)}$ 907를 사용한 경우보다 병소 깊이 증가가 더 빠르게 나타났으며, 회귀 분석 결과에서 R square 값이 0.965와 0.945로 나타나 탈회 기간과 병소 깊이가 매우 높은 상관관계를 가지고 있으며, 병소 깊이의 조절이 매우 용이하다고 사료되었다.

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.277-290
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• 1993

Dental caries is considered to be caused by demineralization by organic acid produced by microorganism. But the formation of subsurface lesion in initial caries make it diffcult to explain by simple demineralization. This study is carried out on the basis of thermodynamic concept proposed by Margolis and Moreno. The purpose of this study is to evaluate the effects of acid concentration and pH of lactate buffer system on the artificial caries lesion progress. 160 teeth without any crack, defect or opaque enamel were used and coated with nail varnish except the window ($2{\times}3$ mm). Under the constant degree of saturation(D.S.). The teeth were divided into 8 groups according to acid concentration(10mM, 25mM, 50mM, 100mM) and pH(4.3, 5.0, 6.0). Each group was immersed in buffer solution for 3, 6, 9, 18 days under controlled temperature($25^{\circ}C$). After cutting through the window and grinding, the specimens, 100-150 um in thickness, were imbibed in water or air and examined using polarilizing microscope. The depth of the surface and subsurface surface lesion were measured. 1. In the constant pH and D. S. value, the subsurface lesion progresses more rapidly as the concentration of lactic acid increases. (0.01, 0.025, 0.05, 0.1) 2. In the constant acid concentration and DS value, the subsurface lesion progresses more slowly as the pH increases. (4.3, 5.0, 5.5, 6.0) 3. The width of surface lesion seems to be constant independant of pH and acid concentration.

• 대한소아치과학회지
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• 제25권4호
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• pp.849-857
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• 1998

The purpose of this study was to investigate whether fluoride-releasing pit and fissure sealant was more effective in preventing caries than conventional non-fluoride-releasing sealant. Specimens 8mm in diameter were made from sound bovine enamel. Fluoride-releasing pit and fissure sealant(Helioseal F, Vivadent, Schaan, Liechtenstein) and non-fluoride-releasing sealant(Helioseal, Vivadent, Schaan, Liechtenstein) were applied to the specimens and artificial caries was induced. Microhardness and the depth of the carious lesion was measured. The following results were obtained: 1. In group 2, sealed with fluoride-releasing sealant, there was a 58.4% decrease in microhardness. This was significantly less than the 84.4% decrease observed in group 1, sealed with non-fluoride-releasing sealant(p<0.01). 2. The average depth of the artificial carious lesion in group 2 was $30.1{\pm}9.8{\mu}m$. In group 1, sealed with non-fluoride-releasing sealant, the lesion was significantly deeper with an average depth of $58.5{\pm}4.9{\mu}m$(p<0.01). 3. Fluoride-releasing pit and fissure sealant was more anticariogenic compared to non-fluoride-releasing sealant.

• 치과방사선
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• 제24권1호
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• pp.85-94
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• 1994

The purposes of this study were clinical comparison and evaluation between digital radiography and conventional radiography for the detection of artificial interproximal caries. Four freshly extracted, unrestored posterior teeth were obtained and caries was simulated by drilling semicircled defects with variable size at the interproximal surface of each tooth. The experiments were performed with IBM-PC/32 bit-DX compatible, video camera(VM-S8200, Hitachi Co., Japan), and color monitor(Multisync 3D, NEC, Japan). Sylvia Image Capture Board for the ADC(analog to digital converter) was used, and spatial resolution was 512 × 480 with 256 gray levels. The obtained results were as follows: 1. At the condition of under exposure, the radiographs were superior to the digital images in readability. Also, as the size of the artificial lesion was increased, readability of the radiographs was elevated. 2. The digital images were superior to the radiographs in readability especially under over exsposure. 3. As the exposure time and size of lesion was increased, the gray level of region of interest of the digital image was decreased proportionally. 4. As the F-value of average gray level of region of interest at individual exposure time and size of lesion, gray level of the all lesion sizes was decreased in comparison with that of the normal enamel.

• Restorative Dentistry and Endodontics
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• 제41권4호
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• pp.255-261
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• 2016

Objectives: This study aimed to analyze the mineral composition of naturally- and artificially-produced caries-affected root dentin and to determine the elemental incorporation of resin-modified glass ionomer (RMGI) into the demineralized dentin. Materials and Methods: Box-formed cavities were prepared on buccal and lingual root surfaces of sound human premolars (n = 15). One cavity was exposed to a microbial caries model using a strain of Streptococcus mutans. The other cavity was subjected to a chemical model under pH cycling. Premolars and molars with root surface caries were used as a natural caries model (n = 15). Outer caries lesion was removed using a carbide bur and a hand excavator under a dyeing technique and restored with RMGI (FujiII LC, GC Corp.). The weight percentages of calcium (Ca), phosphate (P), and strontium (Sr) and the widths of demineralized dentin were determined by electron probe microanalysis and compared among the groups using ANOVA and Tukey test (p < 0.05). Results: There was a pattern of demineralization in all models, as visualized with scanning electron microscopy. Artificial models induced greater losses of Ca and P and larger widths of demineralized dentin than did a natural caries model (p < 0.05). Sr was diffused into the demineralized dentin layer from RMGI. Conclusions: Both microbial and chemical caries models produced similar patterns of mineral composition on the caries-affected dentin. However, the artificial lesions had a relatively larger extent of demineralization than did the natural lesions. RMGI was incorporated into the superficial layer of the caries-affected dentin.