• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.341-353
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• 1995

Previous study had shown the diversities in the propriety for optimal bond strength on the concentration of the etchant. The aim of present study in vitro was to evaluate and compare the shear bond strength of orthodontic brackets to enamel and to measure the depth of etch on the phosphoric acid concentrations. A hundred and seventy six extracted bovine lower centrals were ground to yield flat surfaces and etched by the concentration $0%,\;5%,\;10%,\;20%,\;30%,\;40%,\;50%,\;60%,\;70%,\;80%\;and\;85\%$ of phosphoric acid respectively during 60 seconds. The shear bond strength of orthodontic brackets, the depth of etch and surface roughness of the enamel were measured, and scanning electron microscopic observations on the etched enamel surfaces were carried out. The data obtained from the very experiments were processed and statistically analyzed and evaluated. The gradual increase in the depth of etch to enamel as the accretion of the concentration of the phosphoric acid upto $40-50\%$ and decline henceforth were manifested. The surface roughness showed no correlation with the depth of etch, yet moderate correlation with the shear bond strength of brackets. Scanning electron microscopic investigation revealed that morphological patterns of the etched enamel surfaces for $5\%\;to\;40\%$ of concentrations were even and homogenous, and those for $50\%$ as well as $60\%$ exhibited the overetched and unhomogenous. The shear bond strengths kom $10\%\;to\;60\%$ of concentration showed no statistically significant differences. It was suggested that the shear bond strengths at $5\%\;and\;70\%$ were sufficient to tolerate the force levels of the ordinary orthodontic treatment notwithstanding to be significantly lower than those from $10\%\;to\;60\%$ phosphoric acid solution.

• Journal of Life Science
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• v.25 no.12
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• pp.1399-1407
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• 2015

Klebsiella pneumoniae is found in the normal flora of the skin, mouth, respiratory tract, urinary tract, and intestines in human. However, the stain is opportunistic pathogen, which is the causative agent of community acquired pneumonia. Corn silk has been known to be effective for antimicrobial activity against pathogenic bacteria, including K. pneumoniae, Staphylococcus aureus, Bacillus subtilis, Shigella spp., Salmonella spp., Escherichia coli, Pseudomonas aeruginosa, et al. In this study we focused on the antimicrobial properties of con silk water extract of K. penumoniae. K. pneumoniae isolates K. pneumoniae ATCC 13883 and broad-spectrum β-lactamase (BSBL), exteded-spectrum β-lactamase (ESBL), carbapenemase-producers. Antimicrobial susceptibilities were determined by the disk diffusion method. Searches for bla genes were performed by PCR amplication and direct sequencing. MacConkey agar plate medium was prepared using the corn silk extracts (50% or 100%) instead of distilled water for antimicrobial activity test. The microbial growth inhibitory potential of K. pneumoniae was determined by using the MacConkey agar plate spreading method, and the plate was incubated 18 hr at 37℃. Genes encoding β-lactamases including SHV-1 (n=8), SHV-2a (n=8), SHV-5 (n=2), SHV-11 (n=2), SHV-12 (n=18), TEM-1 (n=10), CTX-M-3 (n=2), CTX-M-14 (n=2), CTX-M-15 (n=1), GES-5 (n=5), KPC-2 (n=6), KPC-3 (n=4), and NDM-1 (n=2) were detected. The corn silk extract showed significantly antimicrobial activity against K. pneumoniae ATCC 13883, but BSBLs, ESBLs, and carbapenemase producers were not. Therefore, corn silk extract is thought to be able to assist in the prevention and rapid recovery of infectious disease caused by K. pneumoniae.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.149-154
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• 2018

This article intended to examine the anti-plaque activity of 4 essential oils of Lavender, Tea tree, Eucalyptus, Lemongrass against Streptococcus mutans. In the results of measuring the anti-plaque effect against Streptococcus mutans, Minimum anti-adhesive concentration of Lavender oil was 1.0% and that of Tea tree, Eucalyptus, lemongrass essential oils was 0.5 %. Also, it was confirmed that the essential oils have the effect of inhibiting acid generation by Streptococcus mutans. It was confirmed that pH of the concentration was lowered by the acid generation under the MAC by measuring pH of the solution after incubating Streptococcus mutans and the essential oils in the thermostatic bath varying their concentration. From these results, the essential oils, particularly, Tea tree, Eucalyptus, Lemongrass essential oils are the natural material inhibiting the plaque generation and the potential that they can be used to develop the oral care products was confirmed.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.227-231
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• 2007

Many of antimicrobial components used in the mouthwash have disadvantages such as coloring of periodontal tissue and homing sensation. To find the more biocompatible antimicrobial agent, we have screened the 2,125 kinds of natural plant extracts obtained from by the Plant Extract Bank (Daejeon, Korea). The antimicrobial activity was determined by spectrophotometric growth inhibition assay for the major dental pathogens. For the Porphyromonas gingivalis, 19 plant extracts had an antimicrobial activity, 17 plant extracts for the Prevotella intermedia, 45 plant extracts for the Haemophilus actinomycetemcomitans and 85 plant extracts for the Streptococcus mutans. Among these effective extracts, 8 kind of natural plant extracts had an antimicrobial activity for more than 3 species of dental pathogens. In our experiment, Cudrania tricuspidata, Morus bombycis and Mallotus japonicas have antibacterial effects on the all kinds of major dental pathogens. Therefore these plant extracts have a possibility to be a candidate for major antibacterial components in dental products.

• Korean Journal of Metals and Materials
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• v.47 no.4
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• pp.256-260
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• 2009

This study examined the effects of plated temperature on the surface morphology and property of an electrodeposited copper foil. The morphology, crystal structure and electric characteristics of the electrodeposited copper foil were examined by scanning electron microscopy, X-ray diffraction, and a four-point probe, respectively. The surface roughness, crystal growth orientation and resistivity could be controlled using various temperature of electrolyte. Large particles were observed on the surface of the copper layer electroplated onto the $30^{\circ}C$. However, a uniform surface, lower resistivity and high flexibility were obtained when a $50^{\circ}C$ electrolyte was used.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.294-300
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• 2021

Necrotizing periodontal disease caused by plaque bacteria is showed clinical findings including pseudo-membrane, interproximal necrosis of the affected area, pain on palpation and gingiva bleeding. Microbiological examination is showed that patients have fusospirochetal bacteria. Two patients who were provisionally diagnosed as necrotizing periodontal disease received nonsurgical periodontal treatments in conjunction with dressing using 3% hydrogen peroxide and local antibiotic delivery. Before and 3 - 5 days after initial treatment, the levels of periodontal bacteria in gingival crevicular fluid obtained using quantitative PCR were compared. After treatment, patients recovered normal gingiva. The number of periodontal diseases related bacterial species decreased from seven or eight to one. As a result, periodontium of patients with necrotizing periodontal disease was recovered to normal periodontium by nonsurgical periodontal treatments.

• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.217-225
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• 2021

We investigated the effect of temperature and stock density on the collection efficiency of oral fluid in the pig farm in Korea. Three pig farms with similar breeding environmental conditions were selected and four pens of each farm (total 12 pens) were tested for the collection efficiency of oral fluid from pigs. Collection rate was considered as significant when oral fluid was collected from 70% of pigs within a pen. In the case of growing pigs, when internal temperature of pig barn increased by one designated degree (5℃), the oral fluid collection rate significantly decreased by 24.7% (P<0.05). The collection rate of oral fluid also decreased by 7.1% (P<0.05) as the density rate increase by one designated degree (12.5%). It was estimated that the collection efficiency of oral fluid decreased when the internal temperature of pig barn was 30℃ or higher, or barn density is higher 25% or high. On the other hand, in the case of stall-housing sows, unlike growing pigs, there was no significant differences according to the temperature, so oral fluid collection was considered to be efficient even in hot season.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.3
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• pp.219-226
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• 2023

Purpose : The purpose of this study was to compare changes of salivary flow rate, salivary buffering capacity, and S. mutans after using a mouthwash containing essential oil or probiotics widely used as oral lactic acid bacteria in the oral environment. Methods : Fifty-three healthy adults aged 20 years or older voluntarily participated in this study after they were informed of the purpose of this study. Subjects were divided into a group treated with probiotics (L. reuteri) and a group treated with mouthwash containing essential oil. To evaluate changes in the oral environment, salivary flow rate, salivary buffering capacity, and S. mutans test were performed at baseline and 4 weeks later. Unstimulated and stimulated salivary flow samples were collected for 5 minutes and results were recorded in ml per minute. Salivary buffering capacity was divided into scores of 1 (low), 2 (moderate) and 3 (high) according to the color of the strip. The amount of S. mutans was classified as scores of 0, 1, 2, and 3 according to the decision table. Data collected in this study were analyzed at the 95 % significance level using the SPSS Version 23.0 program. Results : Both the unstimulated salivary flow rate and the stimulated salivary flow rate increased statistically after the intervention compared to those before intervention in the probiotics group. However, there was no statistically significant difference between the probiotics group and the mouthwash group. Salivary buffering capacity and S. mutans results showed no statistically significant differences between the probiotics group and the mouthwash group either. The salivary buffering capacity and the salivary flow rate showed a positive correlation. Conclusion : To improve the oral environment, such as salivary flow rate and salivary buffering capacity, an optimal product can be selected in consideration of individual preference and cost-effectiveness.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.1
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• pp.15-24
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• 2003

The purpose of this study is to investigate the sterilization effect of Er:YAG laser against the intraoral acid producing bacterium, S. mutans, by irradiating the culture solution containing S. mutans KCTC 3065 with Er:YAG laser having a $650{\mu}m$ diameter beam through the non-contact method. We obtained the following results after examining the temperature changes of the culture solution, numbers of bacterial colonies, and acid-producing ability and attaching ability on teeth by measuring the amount of extracellular polysaccharide produced by S. mutans. The number of bacterial colony was decreased in $10{\mu}l$ culture solution irradiated with laser in overall compared to the control solution. The number decreased as the irradiation intensity and pulse repetition rate were larger and as the exposure time was increased. However, it did not change significantly in $100{\mu}l$ culture solution compared to the control solution. Although the acid-producing ability of S. mutans was inhibited for a certain duration after laser irradiation in 10r1 bacterial culture solution, it did not change in $100{\mu}m$ solution compared with the control solution. The amount of extracellular polysaccharide synthesized by S. mutans was partially decreased through laser irradiation in $10{\mu}m$ culture solution but did not change in $100{\mu}m$ culture solution. Based on these findings, we concluded that Er:YAG laser has an sterilization effect on S. mutans in which we presume that the mechanism is through the heat effect rather than the mechanical effect from development of ultrasound.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.722-727
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• 2003

Xylitol is a 5-carbons carbohydrate, which can be replaced with sucrose for preventing caries. The effect of carbohydrates and their combinations with xylitol was studied for the replication of oral bacteria such as Streptococcus oralis and Streptococcus salivarius. The replication of Streptococcus oralis and Streptococcus salivarius was inhibited according to the increased concentration of xylitol. When Streptococcus oralis was incubated for 8 hours in the media added with lactose or sucrose, the optical density was 0.915 and 1.107, repectively. while being 0.127 and 0.104, respectively in the media combined with xylitol. When Streptococcus salivarius was incubated for 8 hours in the media added with lactose or fructose, the optical density was 1.550 and 0.420, repectively. while being 0.271 and 0.905, respectively in the media combined with xylitol. These results indicated that the replication of Streptococcus oralis and Streptococcus salivarius was changed according to kinds of carbohydrates and combined addition of xylitol.