• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.423-430
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• 2003

The teeth bleaching with bleaching agent is widely used at recent times. Until yet the exact mechanism of the bleaching agent isn't known but it is thought that is by the complex reduction-oxidation reaction of the decomposed free radical from bleaching agent through various ways. In other words, it is supposed that the teeth are whitened by agent's changing chemical structures of stain-causing materials. The purpose of this study is to exam the change of the dentinal character by bleaching agent and to evaluate the safety of this agent. For this study, after applying 10% carbamide peroxide to enamel of human premolar for 6 hours a day for 2 weeks we examined changes of surface morphology, microhardness, composition and contents of minirals in human dentin using SEM, microhardness tester, FT-Raman spectrometer and EPMA and got following results. There was no significant difference in surface morphologic change when we examined the effect of 10% carbamide peroxide which penetrated into dentin after applied on enamel surface comparing with result from specimen in distilled water No change was shown on the surface of peritubular and intertubular dentin within the nanometeric range. The microhardness between bleached teeth and teeth stored in distilled water showed no statistically significant difference FT-Raman spectra of dentin exhibited no change of the component in human dentin. Only the least change in peaks of organic and inorganic materials were detected in Raman intencity. The total content of mineral elements in dentin with no treatment, stored only in distilled water and stored in distilled water after bleaching were $98.73{\pm}1.89,\;98.56{\pm}2.11\;and\;97.47{\pm}2.51$ respectively. Also they showed no statistically significant difference. From above results, the effect of 10% carbamide peroxide bleaching on structure of dentin is very low and the results may confirm the safety of this bleaching agent.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.2
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• pp.170-179
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• 2017

The purpose of this study was to compare the cariogenicity of commercially available bovine milk and low-fat milk in a biofilm model using the CDC Biofilm Reactor. Streptococcus mutans ATCC 25175 biofilms were formed on saliva coated bovine enamel slabs in a CDC Biofilm Reactor. Biofilms were exposed three times per day to one of the following materials: commercial whole milk (fat content: 3.4%), low-fat milk (fat content: 1%), or 0.9% NaCl. Medium pH was measured at different time points. After 5 days, biofilms were separated from slabs to evaluate the CFUs. The biofilm thickness was observed by confocal laser-scanning microscopy (CLSM). Enamel slab's demineralization was assessed by measuring surface microhardness before and after the experiment. For microhardness and CFUs assessment, no significant difference was found among the three groups. All groups showed similar pattern of medium pH change and biofilm thickness. Our results showed that there was no difference in the cariogenicity between whole milk and low-fat milk. Both milks were relatively non-cariogenic compared to the control group.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.32-39
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• 2000

The purpose of this study was to assess the cariogenic potential of five infant formulas in vitro. as compared with 10% sucrose solution and whole bovine milk. Buffering capacities were determined by the amount of 0.1 N lactic acid consumed to titrate the 50ml specimen solutions to pH 4.0. The pH of the specimen solution inoculated by Streptococcus mutans was measured by pH meter and the surface microhardness of primary tooth enamel immersed in the specimen solution was measured by the microhardness tester, before and after 48 hours incubation. Also, the solubility of calcium from synthetic hydroxyapatite was evaluated by atomic absorption spectrophotometer The buffering capacity of infant formulas was higher than that of sucrose solution and lower than that of milk, and there were significant differences among infant formulas(P<0.01). The average pH of infant formulas after 48 hours incubation was lower than that of sucrose solution and milk, and there was significant difference between infant formulas and milk(P<0.05). There were no signifiant differences among oops in the microhardness change of primary tooth enamel and in the amount of dissolved calcium ion from synthetic hydroxyapatite after incubation with Streptococcus mutans. In conclusion, infant formulas seemed to fulfill the basic requirments to cause dental caries in primary teeth, and there were significant differences of cariogenic potential among infant formulas. Cooperative efforts of dentistry and manufacturers to reduce the cariogenic potential of infant formulas would be necessary to prevent the early childhood caries in children.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.662-670
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• 2008

The purpose of this in vitro study was to evaluate the effect of fluoride containing adhesive film on prevention of enamel demineralization. Eighty bovine enamel blocks were divided randomly into 4 groups of 25: (1) APF gel applied ; (2) CavityShield$^{TM}$ applied; (3) 3% fluoride film applied; (4) 5% fluoride film applied; Early caries lesions were produced by placing each specimen into demineralization solution at pH 4.0 for 72 hours. Then lesion of the surface microhardness were measured by the Vicke's hardness test and the lesions depth were measured by polarizing light microscope. The results of the present study are as follows: 1. Difference of microhardness value ($M{\pm}SD$) between control and experimental side was the highest in group II, followed by group IV, III, I but, no significant difference was between group II, III and IV. 2. Difference of mean lesion depth ($M{\pm}SD$) between control and experimental side was the highest in group II, followed by group III, IV and I but no significant difference was between group III and IV. The results of the present study indicate that the fluoride film application is more effective than APF gel and is similar to fluoride varnish application for prevention of dental caries.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.57-64
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• 2008

It is well established that fluoride products play an important role in the prevention and remineralization of carious lesion. Fluoride varnish is a concentrated topical fluoride and varnishes adhere to tooth surface, permitting prolonged fluoride exposure and uptake. In this study, the artificial initial enamel caries was caused on the sound human enamel and divided 60 specimens into three groups. Group 1 and group 2 were treated with the topical application of fluoride varnish and stored in artificial saliva for 1 and 2 weeks. Group 3 was stored in artificial saliva for 2 weeks, which acted as control group. Changes in mineral contents were analysed with the confocal laser scanning microscope. The following results were obtained: 1. In group 1 and group 2, the total fluorescence of the lesion(TFL) was reduced in remineralized area compared to in demineralized area(p<0.05). 2. The total fluorescence of the lesion of remineralized area was more reduced in group 2 than in group 1(p<0.05). 3. The total fluorescence of the lesion was more reduced in group 2 than in control group(p<0.05). 4. Confocal laser scanning microscope can be used in quantitative analysis of remineralization by fluoride varnish.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.83-91
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• 2008

Dental caries which is one of the most common chronic disease complexly developed by the action of oral bacteria, diet, and host factor. Various prevention program enhance resistance of demineralization and reduce the acidogenecity of oral bacteria have been introduced, representative material is fluoride and chlorhexidine. The purpose of the study was to evaluate and compare effectiveness of fluoride varnish and chlorhexidine varnish in vivo. Bovine tooth specimens were implanted in the lower space maintainers and applied with fluoride varnish and chlorhexidine varnish. After seven days in oral environment, metal mesh was covered to make similar condition of plaque accumulation and induce caries. All specimens were analysed by EPMA to evaluate quantitative change of Ca, P and by polarized microscope to identify histological changes. The results were as follows : After initial artificial caries induction in the mouth, there were remarkable enamel caries lesion in the control group under polarized light microscopy. The highest amount of mineral decrease were showed in control group. No statistically significant mineral decrease were showed in fluoride varnish group, while chlorhexidine varnish group showed only significant decrease of P(P<0.05). In conclusion both fluoride varnish and chlorhexidine varnish seemed to be effective for protecting enamel surface from caries activity, although fluoride varnish has more anticariogenic effect than chlorhexidine varnish.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.1
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• pp.27-32
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• 2016

Streptococcus mutans plays a virtal role in trigering dental caries establishment due to its ability to synthesize two significant factors. The two factors are organic acids and glucans. The former demineralized dental enamel and the latter mediates the attachment of bacteria to tooth surface. It is believed that demineralization of dental enamel and attachment of bacteria are the crucial events that indicate and develop dental caries. For this reason, we studied the effect of the ethanol extracts of Radix Pulsatillae on the growth and acid production of S. mutans. Ethanol extracts of the Radix Pulsatillae showed concentration dependent inhibitory activity against the growth and acid production of S. mutans, and produced significant inhibition compared to the control groups (p<0.05). The extracts inhibited S. mutans adherence to hydroxyapatite treated with saliva, and cell adherence was repressed by Radix Pulsatillae. the ethanol extract of Radix Pulsatillae showed remarkable inhibition of glucosyltransferase, which synthesizes water insoluble glucan form sucrose. Phytochemical analysis showed Radix Pulsatillae contained major components such as phenolic compounds, glycosides, steroids, terpenoid, and saponin. These results suggest that Radix Pulsatillae may have anti-cariogenic properties, which may be related with major components such as phenolic compounds, glycosides, steroids, terpenoid, and saponin.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.522-529
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• 2001

This study seeks to know the effect of fluoride topical application on the shear bond strength between enamel and fissure sealant. On group 1,2,3,4, Teethmate A(unfilled sealant) and on group 5,6,7,8 Ultraseal XT(filled sealant) were used. Group 1 and 5 were not pre-treated with fluoride and group 2 and 6 were pre-treated with 1.23% APF for 4minutes. Group 3 and 7 were pretreated with 2.0% NaF for 4 minutes. and group 4 and 8 were pumiced with abrasive containing fluoride for 10 seconds. Prepared specimens were acid etched for 30 seconds using 35% phosphoric acid, and then sealant was cured to the specimen using a 3mm diameter by 2mm height mold. They went through thermocycling. Its shear bond strength was measured, and then acid etched both groups that were pretreated with fluoride and that were not pretreated with fluoride. Then we examined the surface of the specimen with EM and came up with these results. In groups using unfilled sealant(group 1,2,3.4) there were no significant differences between oops pretreated with fluoride and groups not pretreated with fluoride. In groups using filled sealant(group 5,6,7,8), groups 6 and 7(treated with 1.23% APF 2.0% NaF respectively) showed significantly lower shear bond strength, compared to group 5 (not pretreated with fluoride) and group 8 (pumiced with abrasive containing fluoride) (p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.401-410
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• 2006

Dental caries results from localized demineralization of tooth enamel by acids of bacterial origin produced from the fermentation of dietary sugars. A group of related oral bacteria, collectively known as mutans streptococci, are implicated as the primary etiological agents of human caries. Within this group, Streptococcus mutans has been known as a causative agent for dental caries. As well as acid production yielding the demineralization of tooth enamel, adherence and colonization of S. mutans to the teeth are also important for their virulence Cell-surface fibrillar proteins, which mediate adherence to the salivary pellicle are virulence components of mutans streptococci, and primary candidates for a human caries vaccine. Here we report that the AgI/II gene from S. mutans GS-5 were cloned by PCR amplification of the bacterial chromosomal DNA and the integrity of cloned genes were confirmed by nucleotide sequencing. Sequence analyses showed the sequence alignment of 280 nucleotides between the cloned AgI/II and the reported sequence of S. mutans GS-5 showed the perfect match The cloned genes which signal nucleotide was truncated, were transferred into bacterial expression vector and the recombinant proteins were purified as His-tag fusion proteins In order to generate polyclonal antibodies against the recombinant proteins, AgI/II mr, some $100{\mu}g$ of the proteins was injected into mice three times. It can be used for an effective vaccine production to prevent dental caries caused by pathogenic S. mutans.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.165-171
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• 2015

This in vitro study compared the effect of bleaching agent modified by the addition of $TiO_2$ catalyst converged bleaching agent. Nonvital teeth samples were assigned to four group(n=6) according to the bleaching agent: 10% carbamide peroxide(CP) bleaching agen, 10% CP with 10% $TiO_2$ catalyst, 20% CP bleaching agent and 20% CP with 20% $TiO_2$ catalyst. Changes in enamel color were evaluated on minutes 30, 60, 180, 300 and 420. It was found that 20% CP with 20% $TiO_2$ catalysis increased the whiteness and overall color value and showed significantly brightened. The teeth bleaching time was reduced with $TiO_2$ catalyst converged bleaching agent. This result will contribute to development of the teeth bleaching agent.