• Journal of Korean society of Dental Hygiene
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• v.16 no.3
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• pp.383-390
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• 2016

Objectives: The purpose of this study was to examine the correlation between oral malodor and related factors in visitors to preventive dentistry practice lab. Methods: The subjects were selected from 71 visitors to preventive dentistry practice lab in a department of dental hygiene. The subjects were from twenty to twenty nine years old and had no systemic diseases or symptoms. The questionnaire consisted of general characteristics, oral malodor concentration, oral health status, oral health behavior, and self-rated oral malodor. Results: The mean concentration of the oral cavity gas was 50.80. The score of 50.80 was a weak smell by the selected judgement criteria. The oral malodor prevalence rate accounted for 39.1 percent and a weak smell was detected in 40 points. Those having higher oral malodor concentration tended to have lower self-rated oral health status(p<0.05). Conclusions: The results can not be generalized to determine the cause of oral malodor, but self-rated oral health status can be linked to systemic disease control. More investigation should be taken in order to analyzed the correlation between oral malodor and systemic diseases.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.353-359
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• 2012

Purpose: The aim of this study measured and compared the marginal and internal fit of metal cores with two base metal alloy (Ni-Cr alloy(non-beryllium), Co-Cr alloy). Methods: Maxillary right first molar abutment fabricated by titanium was prepared for this study. Impressions(10ea) were made from titanium model, and study models were poured with improved dental stone. Wax cores of twenty were prepared for burn-out and casting. Ten wax cores cast Ni-Cr alloy(non-Be), and finally ten cast Co-Cr alloy. Marginal and internal fit of cores was evaluated using silicone replica technique and digital microscope(x160). The data were statistically analyzed with the independent samples t-test (${\alpha}$ <.05). Results: Mean(standard deviation, SD) marginal and internal fit total size of Ni-Cr alloy(non-Be) group was $73.3(14.4){\mu}m$ and of Co-Cr alloy group $65.6(17.4){\mu}m$. The marginal and internal fit total size of Ni-Cr alloy group(non-Be) was statistically significantly greater than that of Co-Cr alloy group (P=.004). Conclusion: Co-Cr alloy cores in this study had a better marginal fit than Ni-Cr alloy(non-Be) cores.

• International Journal of Oral Biology
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• v.36 no.3
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• pp.117-122
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• 2011

Endothelial cells are a vital constituent of most mammalian organs and are required to maintain the integrity of these tissues. These cells also play a major role in angiogenesis, inflammatory reactions, and in the regulation of thrombosis. Angiogenesis facilitates pulp formation and produces the vessels which are essential for the maintenance of tooth homeostasis. These vessels can also be used in bone and tissue regeneration, and in surgical procedures to place implants or to remove cancerous tissue. Furthermore, endothelial cell regeneration is the most critical component of the tooth generation process. The aim of the present study was to stimulate endothelial regeneration at a site of acute cyclophosphamide (CP)-induced endothelial injury by treatment with human umbilical cord-derived endothelial/mesenchymal stem cells (hEPCs). We randomly assigned 16 to 20-week-old female NOD/SCID mice into three separate groups, a hEPC ($1{\times}10^5$ cells) transplanted, 300mg/kg CP treated and saline (control) group. The mice were sacrificed on days 5 and 10 and blood was collected via the abdominal aorta for analysis. The alanine transaminase (ALT), aspartate aminotransferase (AST), serum alkaline phosphatase (s-ALP), and albumin (ALB) levels were then evaluated. Tissue sections from the livers and kidneys were stained with hematoxylin and eosin (HE) for microscopic analysis and were subjected to immunohistochemistry to evaluate any changes in the endothelial layer. CP treatment caused a weight reduction after one day. The kidney/body weight ratio increased in the hEPC treated animals compared with the CP only group at 10 days. Moreover, hEPC treatment resulted in reduced s-ALP, AST, ALT levels compared with the CP only group at 10 days. The CP only animals further showed endothelial injuries at five days which were recovered by hEPC treatment at 10 days. The number of CD31-positive cells was increased by hEPC treatment at both 5 and 10 days. In conclusion, the CP-induced disruption of endothelial cells is recovered by hEPC treatment, indicating that hEPC transplantation has potential benefits in the treatment of endothelial damage.

• Journal of Technologic Dentistry
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• v.41 no.4
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• pp.359-364
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• 2019

Purpose: The objectives of this study is to collect the opinions of experts in the field of dental lab technology, and to present a plan for reforming the curriculum for producing clinical-based dental technicians. Methods: 71 experts were selected for this study. Experts were grouped into clinicians, educators, and policy-makers. First of all, the purpose and method of this study were explained to experts. After receiving the consent to participate in the research, their opinions were investigated. The survey was conducted through a questionnaire created based on their opinions and opinions collected. Results: The results showed that they were relatively satisfied with the curriculum. In addition, it was found that they hope to increase the proportion of mandatory education of digital dentistry and clinical practice. Emphasis was placed on expanding opportunities for on-the-job training as well as on time for hands-on training. As for admission capacity, the highest opinion was to keep it as it is, followed by the need for reduction. Conclusion: It seems necessary to minimize the difference between the curriculum and the clinical field in order to produce field-oriented dental technicians. To this end, it is necessary to reorganize the operation of field-oriented subjects and to increase the practice time to improve practical skills.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.195-202
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• 2004

• Journal of dental hygiene science
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• v.11 no.4
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• pp.299-303
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• 2011

The purpose of this case report was to present an example of an esthetic and functional rehabilitation of anterior teeth with tetracycline discoloration and minor morphological abnormality of a 39-year old female. A chairside computer-aided design/computer-aided manufacturing (CAD/CAM) system with CEREC AC was applied for the prosthetic procedure and all ceramic crowns made with lithum disilicate (IPS e.max CAD) restored the esthetic and functional features of sixteen anterior teeth successfully.

• Journal of Technologic Dentistry
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• v.26 no.1
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• pp.41-48
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• 2004

Ti-20%Zr(-5%Cr) alloys not containing harmful Al and V were newly designed in order to reveal their possibility for dental casting and melted in an arc melting and casting furnace under Ar atmosphere. The corrosion resistance was studied by anodic polarization test. From the observation of anodic polarization behavior, it was found that the corrosion resistance was markedly increased by the addition of Cr. The corrosion resistance of Ti-20%Zr-5%Cr alloy was superior to that in Ti-6%Al-4%V alloy but almost similar to that in CP Ti using in market place today.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.37-54
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• 2009

The purpose of this thesis is to address the imbalance between supply and demand of dental lab technicians and to propose its solutions by analyzing the improvement of employment rate of graduates of dental technology schools in Daegu area and the supply and demand of the technician workforce. Preliminary and full-scale surveys were performed from Aug. 10 to Oct. 10 in 2008 on 150 junior students of dental technology schools who finished their on-the-job-training and 150 dental technicians who were working for dental laboratory in Daegu by self-assessment questionnaire. Followings are the findings of this study. First, regarding the gender of the dental technicians, 32.7% of respondents were female 67.3% were male. Concerning age, respondents younger than 29 years-old occupied the highest percentage(39.3%). With respect to the lab technology school they graduated, DaeguHealthCollege took the largest proportion of 87.3%. With regard to interpersonal relationship at the school, 58.0% of respondents felt their relationship 'smooth'. Second, about the motive of choosing to be a lab technician, the biggest proportion of the respondents(34.7%) replied that 'because it is professional'. Regarding the degree of satisfaction about the profession, 'so-so' was the answer with the biggest percentage(51.3%) followed by 'satisfied'(32.0%) and 'unsatisfied'(16.7%). It showed that respondents were generally satisfied with their major. Third, regarding relevance of on-the-job-training with 'preparation for the employment', highest percentage of both students and lab technicians(50.0%) replied 'so-so'. With respect to 'necessity of practical education', highest percentage of the students and lab technicians replied 'relating didactic education in college to the real world' with 52.7% and 40.7% respectively. With regard to 'the aim of on-the-sport-training', 'practical training of didactic education' was chosen by 54.0% and 47.3% respectively. Fourth, with regard to the 'types of college education advantageous for the employment', both students and lab technicians groups chose 'practical training' with the highest percentage. Concerning 'helpfulness of clinical training on employment', students answered 'so-so' and 'helpful' by 50.0% and 42.7% respectively and dental technicians replied similarly by 50.0% and 46.0% respectively. Fifth, with regard to the influence of financial factors on the supply and demand of dental technician(question #1), 68.0% of respondents agreed that 'salary plays key role in the supply and demand of the work force'. Concerning the question about working condition, respondents requested better working environment. With reference to interpersonal relationship at the laboratory, respondents replied that interpersonal relationship affects the duration of the employment it was found out that there were many conflicts with colleagues or dental office. Sixth, regarding the satisfaction about their profession according to the characteristics of the respondents more respondents were 'satisfied'(10.30 points) with their profession and 'unsatisfied' were 9.47 points and the difference was statistically significant(p<0.05). According to the findings of this study, practical education on campus and on-the-job-training are as important as didactic education at class due to the characteristics of dental technology major. It was found that more practical training is related to higher employment rate. Therefore, efficiency of on-the-job-training by college education should be increased raise employment rate of the graduates and reduce the unemployment. Up-to-date information needs to be promptly delivered and future vision should be presented to the students to raise their satisfaction about the profession. In addition, to reduce dental technician's frequent change of their workplace after facing with the reality of the profession after graduation, related organizations should make an effort to present better future than now.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.531-537
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• 2006

Lactic acid-producing bacteria (LABs) are known to have various beneficial properties for health. However, they are generally considered to have an adverse effect on teeth, since they produce acid. Nonetheless, milk and cheese containing specific LAB strains were recently found to have an inhibitory effect on dental caries in children, with an inhibitory activity towards the growth of Streptococcus mutans suggested as the responsible mechanism. Accordingly, the current study selected a probiotic candidate for oral health and studied its inhibitory mechanism against dental caries. Twenty-two LAB species belonging to eleven genuses were screened for promoting bone nodule formation using direct microscopic examination. Only one isolate, Weissella kimchii strain PL9001, increased the bone nodule formation significantly. The addition of W. kimchii strain PL9001 to bone cells prepared from mouse calvaria increased the bone nodule formation, calcium accumulation, and activity of alkaline phosphatase (the osteoblastic marker). Moreover, W. kimchii strain PL9001 inhibited the invasion of Streptococcus mutans into bone cells, and an organic extract of the culture supernatant of W. kimchii strain PL9001 inhibited the growth of Strep. mutans. Therefore, the results suggest that W. kimchii strain PL9001 can be used as a preventive measure against dental caries. This is the first time that a LAB has been shown to promote bone nodule formation and prevent the invasion of Strep. mutans into bone cells.

• International Journal of Oral Biology
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• v.35 no.1
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• pp.1-5
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• 2010

Human fibroblasts that maintain the structural integrity of connective tissues by secreting precursors of the extracellular matrix are typically cultured with serum. However, there are potential disadvantages of the use of serum including unnatural interactions between the cells and the potential for exposure to animal pathogens. To prevent the possible influence of serum on fibroblast cultures, we devised a serum-free growth method and present in vitro data that demonstrate its suitability for growing porcine fetal fibroblasts. These cells were grown under four different culture conditions: no serum (negative control), 10% fetal bovine serum (FBS, positive control), 10% knockout serum replacement (KSR) and 20% KSR in the medium. The proliferation rates and viabilities of the cells were investigated by counting the number of cells and trypan blue staining, respectively. The 10% FBS group showed the largest increase in the total number of cells ($1.09\;{\times}\;10^5\;cells/ml$). In terms of the rate of viable cells, the results from the KSR supplementation groups (20% KSR:64.7%; 10% KSR: 80.6%) were similar to those from the 10% FBS group (68.5%). Moreover, supplementation with either 10% ($3.0\;{\times}\;10^4\;cells/ml$) or 20% KSR ($4.8\;{\times}\;10^4\;cells/ml$) produced similar cell growth rates. In conclusion, although KSR supplementation produces a lower cell proliferation rate than FBS, this growth condition is more effective for obtaining an appropriate number of viable porcine fetal fibroblasts in culture. Using KSR in fibroblast culture medium is thus a viable alternative to FBS.