• Journal of dental hygiene science
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• v.16 no.4
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• pp.284-292
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• 2016

Water supplied through dental unit waterlines (DUWLs) has been shown to contain high number of bacteria. To reduce the contamination of DUWLs, it is essential to develop effective disinfectants. It is, however, difficulty to obtain proper DUWL samples for studies. The purpose of this study was to establish a simple laboratory model for reproducing DUWL biofilms. The bacteria obtained from DUWLs were cultured in R2A liquid medium for 10 days, and then stored at $-70^{\circ}C$. This stock was inoculated into R2A liquid medium and incubated in batch mode. After 5 days of culturing, it was inoculated into the biofilm formation model developed in this study. Our biofilm formation model comprised of a beaker containing R2A liquid medium and five glass rods attached to DUWL polyurethane tubing. Biofilm was allowed to form on the stir plate and the medium was replaced every 2 days. After 4 days of biofilm formation in the laboratory model, biofilm thickness, morphological characteristics and distribution of the composing bacteria were examined by confocal laser microscopy and scanning electron microscopy. The mean of biofilm accumulation was $4.68{\times}10^4$ colony forming unit/$cm^2$ and its thickness was $10{\sim}14{\mu}m$. In our laboratory model, thick bacterial lumps were observed in some parts of the tubing. To test the suitability of this biofilm model system, the effectiveness of disinfectants such as sodium hypochlorite, hydrogen peroxide, and chlorhexidine, was examined by their application to the biofilm formed in our model. Lower concentrations of disinfectants were less effective in reducing the count of bacteria constituting the biofilm. These results showed that our DUWL biofilm laboratory model was appropriate for comparison of disinfectant effects. Our laboratory model is expected to be useful for various other purposes in further studies.

• Journal of dental hygiene science
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• v.14 no.1
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• pp.7-14
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• 2014

This study aims to evaluate the impact of varying exposure to dental amalgam on urinary mercury levels in children by measuring the number of amalgam-filled teeth and the variance of mercury concentration in urine over a period of 2 years. A total of 317 (male 158, female 159) elementary school children (1st~4th graders) attending 2 schools in urban regions participated in this study. At 6-month intervals, 4 oral examinations were conducted to check any variance in the conditions of dental caries and the status of dental fillings. Also, urine tests were conducted followed by a questionnaire survey. To elucidate the factors potentially affecting the mercury concentration in urine, t-test, ANOVA, chi-square test and a mixed model were used for the analysis. Regarding the status of dental fillings in line with examination time periods, deciduous teeth had more amalgam-filled surfaces than those filled with resin, whereas permanent teeth had more resin-filled surfaces than those filled with amalgam. A significant relevance was found between the exposure to dental amalgam and urinary mercury levels. Specifically, subjects whose teeth surfaces had been filled with dental amalgam showed higher urinary mercury levels than those who had no dental amalgam fillings. Based on the analysis using the mixed model, the increase in the number of teeth surfaces filled with amalgam was found to be the factor affecting the increase in urinary mercury levels. The urinary mercury levels were found to be highly associated with the exposure to dental amalgam. The more the teeth surfaces filled with amalgam, the higher the urinary mercury levels. Hence, even a trace of dental amalgam fillings can liberate mercury, affecting the variance in the urinary mercury levels. These findings suggest that some criteria or measures should be developed to minimize the exposure to dental amalgam. Moreover, relevant further studies are warranted.

• Journal of dental hygiene science
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• v.13 no.1
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• pp.13-19
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• 2013

This study evaluated the change of color and the microhardness according to time-out using the office bleaching with in vitro test after bleaching one time 1 day per week, total three times, for the control group and three times per 1day for the experimental group. $L^*$ was increased in both groups. Group 1 showed a significant increase statistically between before and after tooth whitening (p<0.05). Group 2 showed a significant increase statistically between before and after tooth whitening (p<0.05). ${\Delta}E^*$ was huge in both groups. In group 1, it was great in terms of statistical significance between 1 day and 7 days after tooth whitening (p<0.05). In group 2, it was the greatest between before and 1 day after tooth whitening and was significant statistically as well (p<0.05). Vickers hardness number (VHN) decreased in both groups. In group 1, VHN decreased over time and the difference was significant statistically (p<0.05). In group 2, VHN decreased over time and the difference was significant statistically (p<0.05). Percentage microhardness loss was great in both groups. In group 1, it was the greatest between 1 day and 7 days after the treatment, and it was significant statistically (p<0.05). In group 2, it was the greatest between before and 1 day after the treatment, and it was significant statistically (p<0.05). Put together, the more frequent tooth whitening a day is, the longer the period of tooth whitening when applying the same frequency, the greater color change was, however the microhardness decreased, in regard to the results over time using 15% hydrogen peroxide tooth whitening product for professionals.

• Journal of dental hygiene science
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• v.13 no.3
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• pp.271-280
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• 2013

This study aims to analyze the effects of tooth-brushing facilities (TBF) at middle schools that installed TBF in 2012 as part of the oral health project in Seongdong-gu, Seoul. The subjects were the first graders at A middle school that installed TBF previously and B middle school that installed TBF in 2012. The results are as follows: DMFT, DMFS and CPI didn't show significant difference by schools (p>0.05), but code (0) was higher and code (2) was lower in female students than male students (p<0.05). As to PHP index, the students at A school with TBF indicated better oral hygiene (p<0.01). In the research on before and after installing TBF, the oral hygiene was improved significantly more after the installation than before (p <0.01). In the comparison on the oral health-related behavior, the percentage of not brushing after lunch was higher B school than A school and the frequency of toothbrushing after lunch was higher A school than B school (p<0.01). About the reasons why not to brush after lunch, there was difference in 'lack of the place' as A school showed 2.6% while B school without TBF indicated 14.2% (p<0.01). About the changes of the oral health-related behavior before and after TBF installation, the percentage of not brushing after lunch increased from 78.7% to 83.8% after the installation. The average frequency of tooth-brushing after lunch for one week also decreased from 0.50 to 0.34 (p>0.05). Among the reasons why not to brush after lunch, 'lack of the place' significantly reduced, but 'because other friends don't do it' increased greatly after the installation (p <0.05). Only with the improvement of oral health knowledge, we cannot expect either clinical or behavioral significance. Not only schools but policies of governmental agencies and financial support, cooperation of community-related groups for program development and evaluation will contribute altogether to helping teenagers to habitualize proper oral health management.

• Journal of dental hygiene science
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• v.17 no.6
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• pp.487-494
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• 2017

There is little evidence on the effects of environmental tobacco smoke (ETS) on prevalence of periodontal disease. The aims of this study were to explore the trends of prevalence of periodontal disease and types of exposure to smoke, including ETS according to the survey year, identify factors affecting periodontal disease, and compare the effect size of periodontal disease between active smokers and secondhand smokers. Data on 11,643 individuals were obtained from the fourth and fifth Korean National Health and Nutritional Examination Surveys. Information on exposure to ETS at home and work was self-reported. Severity of periodontal disease was evaluated using the community periodontal index. A multivariate logistic regression analysis was performed to model periodontal disease using types of smoking and the survey year. Overall, the prevalence of periodontal disease was 26.0% (n=3,029) and about 9% of the study population were secondhand smokers. The prevalence of periodontal disease among smokers was significantly increased according to smoking types by year. Active smokers showed a statistically significant adjusted odds ratio (aOR) for having periodontal disease except in the year 2007, whereas secondhand smokers had significant associations only in 2010 (aOR, 1.68; 95% confidence interval, 1.05 to 2.70) compared to non-smokers. For secondhand smokers, the statistical relationship of predicting periodontal disease was weaker than that of active smokers. However, ETS should separately be considered as an important risk factor for periodontal disease. This study suggested the need for further investigation of the impact of ETS on prevalence of periodontal disease using in-depth research designs and objective measurements for assessing periodontal disease and ETS.

• Journal of dental hygiene science
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• v.15 no.6
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• pp.815-824
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• 2015

This study aims to figure out the current state of health insurance education provided to dentists and personnel in charge of insurance claim as well as the effects of experiences in education on their knowledge of health insurance standard and actual application. As a result of analysis on 100 data sheets related to dentistry and 100 data sheets related to personnel in charge of insurance claim (a total of 200 data sheets), following results were generated. Insurance claim personnels showed higher score than dentist in knowledge of health insurance standard and it was significant statistically. Knowledge of insurance claim personnel showed significant differences in educational experiences, in health insurance for the latest three years and average hours of education per session whereas that of dentists did not indicate any significant differences. The level of practical application of dentists was significantly different (p<0.05) according to experiences in insurance claim, and that of insurance claim personnel significantly varied (p<0.05) depending on age, experiences of insurance education and average hours of education. The longer average hours of education, the higher level of practical application. Experiences of insurance education turned out to affect on the knowledge of health insurance standard significantly (p<0.05) on the part of dentists and insurance claim personnel, and the level of experiences in insurance claim and knowledge of health insurance standard on the part of dentists and insurance claim personnel turned out to affect on practical application significantly (p<0.001). Judging from the result, continuous education needs to be conducted in order to enable dentists and insurance claim personnel to maintain the level of knowledge about health insurance and practical application.

• Journal of dental hygiene science
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• v.6 no.1
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• pp.1-9
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• 2006

Cathepsin K (cat K) is the major cysteine protease expressed in osteoclasts and was thought to play a key role in matrix degradation during bone resorption. It was shown that the intracellular maturation of cat K was prevented by the cAMP antagonist, Rp-cAMP, and the protein kinase A (PKA) inhibitors of KT5720 and H89. In contrast, forskolin, a adenylate cyclase agonist, rather induced Cat K processing and maturation in osteoclasts. Furthermore, to determine whether cat K processing and maturation signaling involves protein kinase C (PKC), mouse total bone cells were treated with calphostin C, a specific inhibitor of PKC, however, no effect was observed, indicating that calphostin C did not affect to osteoclast-mediated cat K processing and maturation. Thus, it is indicated that the cAMP-PKA signaling pathway regulates cat K maturation in osteoclasts. Since secreted proenzymes have the potential to reenter the cell via M6P receptor, to prevent this possibility, it was tested cAMP antagonist Rp-cAMP and the PKA inhibitors KT5720 and H89 in the absence or presence of M6P. Inhibition of cat K processing by Rp-cAMP, KT5720, or H89 was observed in a dose-dependent manner. Furthermore, the addition of M6P resulted in enhanced potency of Rp-cAMP, KT5720 and H89. These dose-dependently inhibited in vitro bone resorption with a potency similar to that observed for inhibition of cat K processing.

• Pediatric Infection and Vaccine
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• v.4 no.1
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• pp.90-96
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• 1997

Purpose : Recently a shift in hepatitis A incidence from children to adults has been well noted. We experienced under 15-years old 31 patients who presented hepatitis A infection. In order to prepare for the prevention on hepatitis A outbreak in the future, we studied the clinical and epidemiologic manifestations of these patients. Methods : We enrolled patients from July to December in 1996 (6 months) and evaluated the monthly incidence, geographical distribution, age and sex, and clinical manfestations, including laboratory fadings. Results : Many cases of hepatitis A occured in the summer months, especially August (16/31 cases). Most of patients (87%) were living in the Seo-Ku area (northwest district of the city). In age distribution, there were no cases under 3 years of age, 3 cases from 4~5 years, 13 cases from 6~10 years, 15 cases from 11~15 years. Clinical profiles showed that dark urine, nausea and vomiting, anorexia, abdominal pain, fever, and fatigue were the common presenting symptoms. The initial presenting laboratory tests included total bilirubin 3.3mg/dl, alkaline phosphatase of 856units/L, and serum asparate aminotransferase and alanine aminolransferase levels of 910IU/L and 1239IU/L, respectively. No patient presented atypical clinical courses or complications. Conclusions : Hepatitis A in children shows benign clinical features. This study showed that the possibility of another outbreak of Hepatitis A in the TaeJon area or elsewhere in the near future Korea will be possible. To prevent an outbreak we will be concerned about the anti-HAV IgG prevalance rate in children and preventive modalities including vaccination against hepatitis A.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.8 no.2
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• pp.127-133
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• 2012

Ehlers-Danlos syndrome (EDS), an inherited connective tissue disorder, is caused by mutations in genes encoding different types of collagen or collagen-processing enzymes. EDS most typically affects the joints, ligaments, skin, and blood vessels. Oral health may be severely compromised in EDS as a result of specific alterations of collagen in orofacial structures. Dental hard tissue defects, root dilaceration, pulp stones, ectopic or delayed eruption, impaction, and periodontal disease could be observed. Therefore, a number of tissue responses related to collagen and precautions should be anticipated when considering dental treatment in EDS. Long-term and comprehensive dental management is required. The purpose of this report is to describe a clinical case of eruption disorders in a patient with EDS.

• Journal of Chest Surgery
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• v.30 no.11
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• pp.1097-1104
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• 1997

The expectoration of blood is always a fearful experience for the patient and a matter of grave concern to the attending physician, because it may be the warning sign of serious diseases. When such bleeding occurs, the possibility of its being due to pulmonary tuberculosis, bronchiectasis or carcinoma of the lung is promptly suggested. Nowadays, with the advance of modern diagnostic studies, differential diagnosis has become possible for the hemoptysis patients to have appropriate treatment. This evaluation is based on the review of 75 cases of patients whom we performed emergency open thoracotomies for 6 years from March 1992 to February 1997 in the Department of Thoracic and Cardiovascular Surgery, Seoul Adventist Hospital. The mean age of the patients was 36.6 years old with a range from 19 to 68, and most prevalent age group was thirties. The most common underlying lung disease causin hemoptysis was tuberculosis(44%). Most accurate diagnostic study was bronchoscopy during hemoptysis(95 Vo) and right middle & lower lobe(17.3%) was the most common site of lesion. Lobectomy(50%) was the most frequent operative method and recurrent hemoptysis(31.6%) was the most common postoperative complication. But most of the patients(82.6%) were completely recovered by surgical treatment. Now we concluded that the proper management of hemoptysis was completed by surgical approach with definite diagnosis and supportive medication.