• 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.

• 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).

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.122-132
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• 1993

The aim of this study was to investigate the level of radiopacity of glass ionomer cements and to determine the optimum level of radiopacity that is the most compatible with the radiographic diagnosis of secondary caries. The experiments were performed in two parts. In the first part, the radiopacities of 9 glass ionomer cements (FI, FII, FI-LC, FII-LC, SI, SII, Vit, B-VLC, AC) and base materials(Ultra-Blend, Zinc phoaphate cements, Cavitec, Dycal) were measured by densitometer. Then all experimental materials were divided into 5 groups based on the level of radiopacity of enamel and dentin. In the second part, class III cavities with or without secondary caries were prepared in extracted anterior teeth. The representative materials of each group with different radiopacities were inserted into each cavity. The radiographs were interpreted by 15 dentists and seconsary caries were diagnosed according to a five-point confidence rating. Sensitivity and ROC analysis were used to compare observer performance. The following results were obtained : 1. The radipacity of glass ionomer cements varied between 1.111mm Al and 6.011mm Al equivalent. 2. Among experimental materials, three materials in group I had lower radiopacity than that of dentin. The radiopacity of two materials in group II slightly exeeded that of dentin. Three materials in group III had slightly lower radiopacity than that on enamel. The radiopacity of one material in group W was slightly higher than that of enamel. Four materals in group V had the radiopacity that exeeded over 2.0mm AI equivalent to that of enamel. 3. The group IV was the highest for sensitivity and the group V was the highest for ROC area. However, no significant differences were obtained among group II, III, IV and V (P<0.05) but only group I was significantly lower(P<0.01). 4. In comparison with the observer performance for the radiographic diagnosis of secondary caries, the group II, III, IV, and V were superior to the group I (P<0.01). And so the optimum level of radiopacity to detect the secondary caries was the radiopacity that is higher than that of dentin.

• KSBB Journal
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• 제8권2호
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• pp.126-132
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• 1993

The objective of this study was to develop an artificial dentin for easy handle and accurate observation of the mechanism on dental caries and to screen biologically active materials from the extracts of traditional plants and fruits for prevention of early dental cares. In order to produce disc PAHA (artificial dentin), the powdered hydroxylapatite was immobilized in a 20% polyacrylamide gel. The characteristics of disc PAHA was very similar to the surface, figure and lattice of human enamel. After decalcification in 0.1M citric acid based on observation with SEM. The critical point of decalcification of disc PAHA by acids was found to be pH 5.0-5.5, which was hi agreement with human enamel. The degree of decalcification from disc PAHA in 0.1M citric acid solution was sixfold higher than that of human enamel. This result suggested that disc PAHA would be useful as a substitute of human enamel for in vitro experiment. The extracts of garlic and Flower Apple A, B seemed to inhibit growth of S. mutans. Especially, when the 300$\mu\ell$ of its extracts added to the medium to incubate S. mutans, F. apple B showed strongly an inhibitory effect in both the growth of S. mutans and the synthesis of insoluble glucan.

• 한국치위생학회지
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• 제12권2호
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• pp.335-343
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• 2012

Objectives : The aim of this investigation was to evaluate the remineralization effect of Bamboo salt and NaF+Bamboo salt solutions on bovine enamel formed incipient artificial enamel caries by microcomputed tomography (micro CT). Methods : Experimental solutions were distilled water(negative control), 2% sodium fluoride solution (2% NaF group), 3% bamboo salt solution (3% BS group) and the solution mixed 2% sodium fluoride solution and 3% bamboo salt solution (2% NaF+3% BS group). Specimens were prepared from extracted bovine teeth and divided into 4 groups of 10 specimens each by randomized blocks according to density. Then the specimens surface were divided equally into three parts to observe sound enamel area, incipient enamel carious area and remineralized enamel area. Only one-third of specimen surface was coated with nail varnish and these were exposed to a lactate carbopol buffer system for 72 hours. Then one-half of the demineralized enamel area was coated with nail varnish. The specimens were carried out under pH cycling model for 14 days as follows; samples were immersed in each experimental solution for 2 mins 3 times per day, demineralized for 4 hours and in mixed saliva for the remaining hours. After pH cycling, density was measured using micro CT. Results : All experimental groups showed remineralization effects except for negative control group(p<0.05). The differences of density after experimental solution treatment were statistically significant difference among 4 groups (p<0.01). The density difference values of groups were $0.04{\pm}0.01$ in negative control group, $0.19{\pm}0.01$ in 2% NaF group, $0.14{\pm}0.01$ in 3% BS group, and $0.21{\pm}0.01$ in 2% NaF+3% BS group. Conclusions : The bamboo salt solution showed remineralization effects on incipient artificial enamel caries and the solution mixed sodium fluoride solution and bamboo salt solution showed more remineralization effects than the bamboo salt solution. Thus, it is suggested that bamboo salt can be used as remineralization agent in incipient enamel caries lesion.

• 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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• 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.

• 대한소아치과학회지
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• 제33권2호
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• pp.201-206
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• 2006

건전한 치질에 탄산가스 레이저의 조사로 내산성을 증가시키거나 탄산가스 레이저의 조사 전 후에 국소적 불소도포를 함께 시행함으로써 치아우식증 예방효과를 얻을 수 있다. 따라서 이 논문에서는 치아의 법랑질 평활면에 레이저를 조사한 후 법랑질 표면의 변화를 주사 전자 현미경과 원자 현미경을 통하여 관찰하고 불소도포와 레이저 조사를 병용하였을 경우의 차이 및 원자 현미경의 효율성을 알아보고자 한다. 그 결과 대조군과 비교 시 레이저를 조사한 군들에서 미세한 균열과 소와 및 입자형 성상이 관찰되었으며, 불소도포 시에는 좀더 평활한 표면을 보였다. 이러한 레이저와 불소의 병용은 치아 표면에 칼슘, 인 불소가 재흡착되어 표면에 입자형태를 보이며 이것이 치아우식증에 대한 저항성을 나타내는 원인 중 하나라고 생각된다.

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.635-641
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• 1996

This study was designed to evaluate the anti cariogenic effect of F in primers, bonding agents, composite resins or glass ionomer cements in enamel. Twenty-five extracted teeth were selected and a cavity was prepared on either the buccal or the lingual surface of each tooth. After pumicing and etching, the samples were divided into 5 groups. In group A, the samples were primed, bonded and filled with ART bond and Brilliant Enamel (Coltene, Switzerland). Group B composed of Optibond and Herculited XRV (Kerr, USA), group C composed of Syntac and Tetric(Vivadent, Lichtenstein), and group D composed of Scotch-bond Multipurpose and Z 100 (3M, YSA). In group E, the samples were filled with glass ionomer cement (Fuji II LC, Japan), All surfaces except the 2mm beyond the cavosurface margin of the sample were protected, and samples were then put into an acid buffer for 3 days to develop the initial caries. The samples were then sectioned through the filling body into thin wafers and then examined with a polarizing microscope under water imbibition. The fluoride in primer, bonding agent, or composite filling material did not prevent the initial caries in the enamel area adjacent to the filling body whereas the fluoride in the glass ionomer did prevent the initial stage caries.

• 대한소아치과학회지
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• 제30권1호
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• pp.1-9
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• 2003

초기 우식병소와 건전한 치질은 광학적 특성이 다르다는 사실에 근거하여 치과 치료용으로 개발된 가시광선 영역의 레이저의 형광현상과 광활성재를 이용하여 우식 치질과 건전한 치질간의 광학적 특성의 차이를 색조의 차이로 유도 전환함으로써 초기 우식 병소를 조기에 시각적으로 탐지하여 진단하는 방법을 개발하는데 본 연구의 목적이 있다. 소의 치아를 이용하여 여러 단계 깊이의 인공우식병소를 유발하고 우식병소의 표면에서 아르곤 레이저를 조사하여 건전 치질과 우식 치질 사이의 반사된 형광강도의 차이를 컴퓨터 영상분석프로그램을 통해 측정하였다. 또한 광활성재를 병소의 표면에 도포하여 형광현상의 색조대비 증진효과를 평가하였다. 실제 조직학적 병소와 레이저 형광법 사이의 상관관계 분석 및 회귀 분석을 통하여 다음과 같은 결과를 얻었다. 레이저 형광법에 의한 우식 치질은 건전 치질보다 어둡게, 그리고 광활성재를 도포한후 레이저 형광법으로 관찰한 우식 병소는 건전 치질 보다 밝게 관찰 되었으며 광활성재를 이용한 레이저 형광법이 탈회의 초기단계에서는 레이저 형광법에 비해 진단학적 민감도가 컸다.