• Journal of Life Science
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• v.31 no.1
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• pp.100-108
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• 2021

In the oral cavity, there are hundreds of microbial species that exist as planktonic cells or are incorporated into biofilms. The accumulation and proliferation of pathogenic bacteria in the oral biofilm can lead to caries and periodontitis, which are typical oral diseases. The oral bacteria in the biofilm not only can resist environmental stress inside the oral cavity, but also have a 1,000 times higher resistance to antibiotics than planktonic cells by genes exchange through the interaction between cells in the oral biofilm. Therefore, if the formation of oral biofilm is suppressed or removed, oral diseases caused by bacterial infection can be more effectively prevented or treated. In particular, since oral biofilms have the characteristic of forming a biofilm by gathering several bacteria, quorum sensing, a signaling system between cells, can be a target for controlling the oral biofilm. In addition, a method of inhibiting biofilm formation by using arginine, an alkali-producing substrate of oral bacteria, is used to convert the distribution of oral microorganisms into an environment similar to that of healthy teeth or inhibit the secretion of glucosyltransferase by S. mutans to inhibit the formation of non-soluble glucans. It can be a target to control oral biofilm. This method of inhibiting or removing the oral biofilm formation rather than inducing the death of pathogenic bacteria in the oral cavity will be a new strategy that can selectively prevent or therapeutic avenues for oral diseases including dental caries.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.315-322
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• 2021

The purpose of this study was to examine the correlations of oral myofunction and oral environment for the elderly with systemic diseases and to suggest need to improve oral health for the elderly. Data were collected from 64 elderly over the age of 65, from April to June 2019. Data were surveyed on general characteristics, oral myofunction, oral health-related quality of life, oral bacteria. Analysis was performed using PASW Statistics ver 18.0. The subjects were 43.8% systemic diseases, among them 40.6 percent of the people with more than two. The number of functional teeth was 18.6. Age was negatively correlated with functional teeth(r=-.384, p<.01) and tongue pressure (r=-).104, p<.001). Tongue pressure was a positive correlation with lip force(r=.279, p<.05). Age and total number of bacteria was negative correlation(r=-.336, p<.01). The functional teeth and total number of bacteria was positive correlation(r=.551, p<.001). The number of systemic diseases and total number of bacteria was positive correlation(r=.327, p<.01) the analysis of oral myofunction and oral bacteria in older patients with systemic diseases It was meaningful in suggesting a plan to improve oral health for the elderly. A practical policy plan was required to improve the quality of oral health life in a super-aged society.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.511-519
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• 2021

This study examined the effects of the levels of depression and oral health on the quality of life in workers participating in a self-sufficiency program in the Seoul metropolitan area. As for the study method, a questionnaire survey was conducted from July 26 to September 5, 2020, targeting 569 workers participating in a self-sufficiency program. Depression, Perio-Quotient Index, self-diagnosed oral symptoms, and oral health quality of life were the survey items investigated. The results were as follows. In the workers with systemic diseases, depression, Perio-Quotient Index, oral symptoms, and oral health quality of life were all negative. The level of depression was highly negative in both Perio-Quotient Index, oral symptoms, and oral health quality of life, showing statistically significant differences. In addition, depression showed a strong negative correlation with the Perio-Quotient Index, oral symptoms, and oral health quality of life. Depression, Perio-Quotient Index, and particularly oral symptoms negatively affected oral health and the quality of life. As workers participating in a self-sufficiency program are vulnerable to oral health problems, oral health education is required for the correct awareness and management of oral health, and oral health policy improvement for socially vulnerable groups is essential to ensure continued oral health management.

• Journal of Digital Convergence
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• v.19 no.3
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• pp.245-251
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• 2021

This study was to investigate the effect of the new surface treatment method of zirconia on the shear bond strength with resin cement. The zirconia specimens were classified according to the surface treatment. CON: non-treatment, HF: 10 minutes exposure to 9% HF, ZS15: Apply 15% ZrO2 slurry, ZS30: Apply 30% ZrO2 slurry, ZS50: Apply 50% ZrO2 slurry. The resin cement was layered on the surface treated zirconia, and the shear bond strength between the zirconia and the resin cement was measured after thermo-cycling. The statistical methods for shear bond strength were Kruskal-Wallis test, Mann-Whitney U test, and Bonferroni correction(α=.05/10=.005). ZS15, ZS30, and ZS50 groups treated with zirconia slurry showed higher shear bond strength than CON and HF groups(p<.05/10=.005). Within the limits of this study, the surface treatment using zirconia slurry increased the shear bond strength with resin cement. The new surface treatment method complements and improves the limitations of the adhesion of zirconia, so that various clinical applications of zirconia can be expected.

• Clean Technology
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• v.26 no.4
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• pp.270-278
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• 2020

Palladium (Pd) has been widely used in various industrial applications such as jewelry, catalyst, and dental materials despite its limited resources. It has been gaining attention to recover Pd with high purity from the spent materials. This study investigated the optimum conditions for the leaching and recovery of metallic Pd. The leaching parameters are HCl concentration, temperature, time, concentration of oxidants, and pulp density. 97.2% of Pd leaching efficiency was obtained in 3 M HCl with 3 vol% oxidants at 80℃ for 60 min. The ratio of hydrogen peroxide to sodium hypochlorite played a critical role in the leaching efficiency due to the supply of Cl- ions in the leachate. Moreover, the complete recovery of Pd in the leachate was achieved at 80℃ with 0.3 formic acid/leachate after adjusting the pH value of 7. This situation was ascribed to the decomposition of formic acid into hydrogen gas and carbon dioxide at 80℃. ICP-AES and XRD characterized the recovered Pd powder, and the purity of the recovered powder was found to be 99.6%. Consequently, the recovered Pd powder with high purity could be used in circuits, catalyst precursors, and surgical instruments.

• 한국노년학
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• v.40 no.2
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• pp.227-237
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• 2020

The purpose of this study is to understand using of antithrombotic agents in clinical settings. The number of patients receiving antithrombotic therapy is increasing in the long term due to the increased prevalence of cardiovascular disease in the elderly. There is a guideline for discontinuation of antithrombotic treatment before dental treatment, but the present study shows that there is a difference from the actual clinical situation. We used an online survey methodology to involve 1000 participants. The questionnaires were asked about general items and Clinical experience such as history of antithrombotic history, experience of complications due to antithrombotics, discontinuation of use, reasons for discontinuing use. The result is as follows. The incidence of delayed bleeding was found to be 55.1%, and discontinuation of antithrombotic therapy before withdrawal was 87.8%. Among respondents 98.3% responded that they stopped antithrombotics because of delayed bleeding and 57.4% responded that they would stop for three to five days. Korean dentists maybe cope with delayed bleeding considering the emotional problem of the patient, the relationship with the patient's physician, and the additional socioeconomic problems.

• The Korean Society of Law and Medicine
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• v.22 no.3
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• pp.97-124
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• 2021

In medical institutions, there are radiation-related workers such as radiological technologists, physicians, dentists, and dental hygienists who handle diagnostic radiation generators. Also, there are work assistants, such as nurses and assistant nurses, who assist in radiation treatment or transfer patients to the radiation examination room. Radiation exposure management for radiation-related workers is carried out under the 「Medical Service Act」, but there is no legal basis for work assistants, etc. And the management of radiation exposure for diagnosis is regulated by the 「Medical Service Act」, and the management of radiation exposure by therapeutic radiation and nuclear medical examination is governed by the 「Nuclear Safety Act」. Thus, to improve the management of radiation exposure for diagnosis, the regulations on radiation exposure management for diagnosis under the 「Medical Service Act」 were compared and reviewed with those of the 「Nuclear Safety Act」. As a result, the main contents are as follows. First, it is necessary to legislate to include nurses, assistant nurses, and clinical practice students who are likely to be exposed to radiation besides radiationrelated workers as subjects of radiation exposure management for diagnosis. Second, when a radiation-related worker for diagnosis is confirmed to be pregnant, the exposure dose limit should be defined. Third, it is necessary to revise the regulations on the types of personal exposure dosimeters in the 「Rules on the Safety Management of Radiation Generators for Diagnostics」. Fourth, it seems that health examination items for radiation-related workers, radiation workers, and frequent visitors should be the same. Fifth, It is necessary to unify and regulate diagnostic radiation and all medical radiation, including therapeutic radiation and nuclear medicine, in one legal system.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.370-378
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• 2021

Purpose. The purpose of this study was to evaluate the currently published literatures investigating the accuracy of computer-aided design and computer-aided manufacturing removable partial denture (CAD-CAM RPD) framework with different manufacturing techniques and methods. Materials and methods. A comprehensive search for literatures was conducted in PubMed database using specific keywords with the patient, intervention, comparison, and outcome (PICO) question, "Is there a difference in accuracy of RPD frameworks manufactured using digital workflow according to the manufacturing process and methods?" Results. A total of 7 articles were selected. Two studies compared intraoral scanning and laboratory scanning for RPD frameworks and had heterogenous results. In the studies using different manufacturing process, RPD frameworks had clinically acceptable accuracy in both subtractive and additive manufacturing. Polyetheretherketone (PEEK)-milled RPD frameworks showed higher fit accuracy than traditionally casted or 3D printed RPDs. Direct milling method showed a higher accuracy than indirect milling method. However, in rapid prototyping, indirect method showed higher accuracy than direct method. Conclusion. The RPD frameworks fabricated using CAD-CAM technology showed a clinically acceptable level of accuracy regardless of manufacturing process or techniques. Consistent results have not been reported regarding the digital impression methods, which were intra oral scanning or laboratory scanning, and further studies are needed.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.2
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• pp.90-96
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• 2022

Purpose: The purpose of this study was to investigate antimicrobial activity of extracts from shiitake mushroom against periodontopathogens and its cytotoxicity for human gingival fibroblast. Materials and Methods: Shiitake mushroom was soaked in water and acetone, and the supernatant was dried to collect its extract. The susceptibility of periodontopathogens for the extracts was investigated. Human gingival fibroblast was treated with the extracts, and the cell viability was measured CCK-8 solution. Results: The water extract from shiitake mushroom significantly reduced the growth of periodontopathogens at 2.5 mg/ml (P < 0.05). The acetone extract significantly inhibited the growth of Porphyromonas gingivalis and Tannerella forsythia at 0.32 mg/ml and Treponema denticola growth at 0.64 mg/ml (P < 0.05). The cytotoxicity of the extract was shown at a concentration of 2.5 mg/ml. The extracts with a concentration of 1.25 mg/ml appeared to be reduce cell viability after 4 h. Conclusion: The extracts of shiitake mushroom have antimicrobial activity against periodontitis-causing bacteria and relieving inflammation. Therefore, the extracts may be a candidate for preventing and treating periodontal disease.

• Advanced Industrial SCIence
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• v.2 no.4
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• pp.1-10
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• 2023

The purpose of this study is to verify the mediating effects of job insecurity on the relationship between COVID-19 risk perception and mental health in hotel workers. For this study, a sample of 633 hotel workers completed the questionnaires: COVID-19 risk perception, job insecurity, depression, anxiety, somatic symptoms. The data was analyzed by SPSS 25.0 program and PROCESS macro program. The main results can be summarized as follows. 1. The risk group of the job insecurity had a significantly higher level of mental health(depression, anxiety, somatic symptoms) compared with the normal group. 2. COVID-19 risk perception showed a significant effects on job insecurity and mental health(depression, anxiety, somatic symptoms). 3. The results showed a partial mediating effects of job insecurity on the relationship between COVID-19 risk perception and mental health(depression, anxiety, somatic symptoms). On the basis of the results, we discuss that hotel workers have the vulnerability of mental health in disaster situations such as COVID-19 pandemic, and that mental health risk increases due to the job insecurity caused by COVID-19. we propose the need to support human resource management measures and psychological programs for hotel workers.