• The korean journal of orthodontics
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• v.12 no.1
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• pp.15-20
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• 1982

The requirement of ideal orthodontic direct bonding adhesive should include longevity of bond, ability to withstand a variety of forces, resistance to the degrading effects of the oral environment, and ability to be easily removed without affecting the integrity of the enamel. The purpose of this study was to evaluate the adhesive properties of recently developed 3 orthodontic directbonding adhesives by testing the tensile strength. 75 premolars extracted for orthodontic treatment were used. The tensile strength was tested by Tensilon/UTM-1-10000C after 24 hours from bonding. Following results were obtained; The mean tensile strength of each product was higher than the maximum force $(29kg/cm^2)$ exerted on a bracket during orthodontic treatment. The tensile strength of Mono-Lok was statistically higher than Concise and Dyna-Bond, although there was no difference between the tensile strength of Concise and Dyna-Bond statistically. Of the filure, the combination type of failure $(68\%)$, where part of the adhesive remained on the tooth and part on the bracket was the most common type. The second type of failure $(22.7\%)$ occurred at the toothadhesive interface and the last type of failure $(9.3\%)$ occurred at the adhesive-bracket interface.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.144-152
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• 2004

The aim of this study was to evaluate the resistance to degradation of three commercial compomers in an alkaline solution. Dyract(Dentsply), Elan(Kerr) and F-2000(3M) polyacid modified resin composites(compomers) were used in this study. The resistance to degradation was evaluated on the basis of mass loss(%), degradation $depth({\mu}m)$ and Si, Al, Ba loss(ppm). The results were as follows : 1. The mass loss of each brand was $1.42%{\sim}2.14%$ and there was no statistically significant difference of mass loss among Dyract, F2000 and Elan. 2. The degradation layer depth of each brand was $182.92{\sim}227.7{\mu}m$ and there was no statistically significant difference of degradation layer depth among Dyract, F2000 and Elan. 3. There was statistically significant differences in Si-loss and Al-loss among three compomers (p<0.05). Si loss was the highest value in Dyract and Al loss was the highest value in F2000. 4. There was statistically significant correlation between mass loss and degradation layer depth (r=0.60, p<0.05). 5. In SEM finding, there was some destruction of compomer matrix-filler interface in post-exposure specimen to NaOH solution. As the matrix decreased, the filler particles distinguished and the periphery of the filler particles appeared whitish color due to degradation.

• The Journal of the Korea Contents Association
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• v.15 no.11
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• pp.329-337
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• 2015

Fluorine is an element that promotes dental caries preventive effect at proper concentration level, but may have significantly undesirable impact on dental caries if correct information of fluorine is not recognized. Therefore, this study is intended to evaluate fluorine awareness among the adults in their 20s and analyze oral health conditions based on such awareness in order to promote dental caries preventive effect and convey correct knowledge of fluorine. For this study, 82 adult men and 102 adult women in their 20s, all of whom lived in Daegu, Gyeongsangbuk-do, were surveyed from May 1, 2014 to June 30 of the same year, along with oral health examination to evaluate their oral health conditions. The results of the analysis showed that 19.46% of respondents answered "No" to the question related to awareness towards the use of fluorine in DT rate dental clinic based on the degree of fluorine awareness, which was higher than 11.10% who answered "Yes"(p<.05). Moreover, 18.32%of respondents answered "No" to the question related to whether they were checking the label indicating the fluorine content in product, which was the highest rate, suggesting that the rate was higher when there was stronger tendency to avoid reading the precaution notice (p<.05). In addition, 71.98% of respondents answered "Yes" to the question associated with the awareness to the use of fluorine in FT rate dental clinic based on the fluorine awareness, which was higher than 49.04% of respondents who answered "No" (p<.05). This study is meaningful in that it provides basic data for the implementation of fluorine prevention projects in the period ahead by determining the effect of fluorine awareness on oral health conditions. Based on aforesaid results, both educational and promotional activities need to be carried out vigorously to help raise fluorine awareness.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.403-411
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• 2001

The aim of this study was to evaluate the resistance to degradation of four commercial composite resins in an alkaline solution. The brands studied were Unifil(GC, Japan), Palfique(Tokuyama Japan). Definite$Degussa-H\ddot{u}ls$ AG, Germany). Revolution(Kerr, U.S.A.). Preweighed discs of each brand were exposed 0.1N NaOH solution at $60^{\circ}C$. After 14 days they were removed, neutralized with HCl, washed with water and dried. Resistance to degradation was evaluated on the basis of following parameters: (a) mass loss(%) - determined from pre-and post-exposed specimen weights; (b) Si loss(ppm) - obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth$({\mu}m)$ - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were follows: 1. The mass loss of Unifil was 3.21%, it was the highest of materials. But, there was no significant difference among the materials. 2. The degree of degradation layer depth was $107.69\sim47.40{\mu}m$, the sequence of the degree pf degradation layer depth was in descending order by Unifil, Palfique, Revolution, Definite. There was significant difference among the materials except Palfique and Definite. 3. The Si loss of Paltique was 8940.0ppm, it was the highest. There was significant difference among the materials, except Revolution and Definite(p<0.05). 4. The correlation coefficient between mass loss and degradation depth was relatively high(r = 0.06, p<0.05). 5. There was no significant coefficient correlation between Si loss and mass loss, and/or the degree of degradation layer depth and Si loss. 6. When observed with SEM, destruction of bonding is observed between resin matrix and filler. Above results suggested that the hydrolytic degradation is considered as evaluation factor of composite resins.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.190-201
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• 2004

The aim of this study was to evaluate the resistance to degradation and to compare the wear resistance characteristics of four esthetic restorative materials in an alkaline solution. The brands studied were Charmfil, Charmfil flow(composite resin), Compoglass F and PrimaFlow(compomer). The results were as follows: 1. The mass loss were not significantly different among the materials(p>0.05). 2. The sequence of the degree of degradation layer depth was in descending order by Compoglass F, PrimaFlow, Charmfil, and Charmfil flow. There were significant differences between Compoglass F and the others(p<0.05). 3. The sequence of the Si loss was in descending order by Charmfil flow, Charmfil, PrimaFlow, and Compoglass F. There were significant differences among these materials(p<0.05). 4. When observed with SEM, destruction of bonding between matrix and filler was observed and when observed with CLSM, the depth of degradation layer of specimen surface was observed. 5. The sequence of maximum wear depth was in descending order by Comfoglass, PrimaFlow Charmal, and Charmfil flow. There were significant differences among these materials(p<0.05). 6. The correlation coefficient between Si loss and degradation layer depth (r=0.602, p<0.05) Vicker's hardness number and maximum wear depth (r=0.501, p<0.05) were relatively high. These results indicate that wear and hydrolytic degradation may be considered to be evaluation factors of composite resins and compomers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.9
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• pp.1380-1387
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• 2014

The purpose of this study was to develop a mouthwash product with solid fermented oriental medicinal herb (OMH). Solid fermentation of magnolia, liquorice, and cnidium by Phellinus linteus mycelium was carried out successfully when 30% water was added to the medium, whereas 10% brown rice powder was required as an extra nutrient for solid fermentation of mint besides water. The amount of total phenol compounds and DPPH radical scavenging activity of OMH increased significantly (P<0.05) upon solid fermentation. Anti-microbial activities of fermented OMH also increased and were approximately 100-fold greater than those of unfermented samples. Oral pathogens such as Staphylococcus epidermis, Streptococcus pyogenes, Candida albicans, or Streptococcus mutans were used for determination of anti-microbial effects of OMH. Formulation of the mouthwash was developed based on the results of the sensory evaluation. Among seven formulas, the best formula chosen by the sensory evaluation was as follows: mouthwash prepared with 0.075% ethanol extract of solid fermented OMH as a main ingredient, 83.64% hot water extract of mint and clove (100:15, v/v) as a mouthwash base component, and other miscellaneous ingredients, including sodium fluoride, menthol, and surfactants. Data from a consumer's preference test with 30 participants, overall acceptance, and willingness to buy the product developed in this study were all significantly higher for the tested mouthwash compared to mouthwash on the market manufactured with OMH but with a different formula. Duration of freshness of the mouthwash after usage as determined by Breath Checker was not significantly different between the two samples, although the duration of our product was slightly longer than that of the commercial product mentioned above.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.370-378
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• 2000

The composite restorative resins have their insufficient resistance to wear. The subsurface degradation within the restoration is considered to be associated with wear. The aim of this study was to evaluate the resistance to degradation of six commercial composite resins in an alkaline solution. The brands studied were Clearfil APX(Kuraray), Heliomolar(Vivadent), Surefil(Dentsply), TPH(Dentsply), Tetric Ceram(Vivadent), and Z100(3M). Preweighed discs of each brand were exposed 0.1N NaOH solution at $60^{\circ}C$. After 14 days they were removed, neutralized with HCL, washed with water and dried to constant mass at $60^{\circ}C$. Resistance to degradation was evaluated on the basis of the following parameters: (a) mass loss(%) - determined from pre-and post-exposure specimen weights; (b) Si loss (ppm)-obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth$({\mu}m)$ - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were as follows: 1. The mass loss was in descending order by Z100, TC H, S, CL, TPH and in the range of $0.45\sim3.64%$ 2. The degradation layer depth was in descending order by H, Z100, S, TC, TPH, CL and in the range of $10.85\sim73.38{\mu}m$ 3. For the Si concentration, Z100 was the highest of all 4. The highly significant correlation(r=0.81, p<0.05) was observed between mass loss and degradation depth. 5. Under scanning electronmicroscopy, the degradation of connection between resin matrix and fillers was observed 2 weeks after soaking in NaOH solution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.370-378
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• 2015

Oral health is a critical factor for diagnosing overall health, as poor oral health has a negative impact on food intake and results in deterioration of nutritional status. The purpose of this study was to research the needs for food developments for the elderly based on their oral and overall health status. Oral status was significantly associated with self-reported health status, and dry mouth (lack of saliva) especially showed a significant relationship with negative self-perception of both oral and overall health. For both elderly men and women, fish and leafy vegetables were the most preferred side dishes. Bread, rice cake, and beverage-type foods were also preferred for snack development. Disease status of the elderly was significantly related with their preference for food development. For instance, those with diabetes were more likely to ask for anti-diabetic diets. The most important factor for the elderly in choosing food was nutritional balance, and less than 3,000 won was cited as an affordable price. The results could be utilized as basic data to develop foods for the elderly.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.1
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• pp.67-73
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• 2011

Dental bacteria can cause gum diseases, i.e. gingivitis and periodontitis, by inducing inflammation in human gingiva. Therefore, the most effective way to prevent and treat gum diseases is the control of the inflammatory reactions induced by dental bacteria. Almost all present dental care products contain anti-bacterial agents to eliminate dental bacteria. However, recent studies report that even heat-killed dental bacteria can induce the inflammation responses in oral cells. Therefore, the method using anti-bacterial agents should be improved for better anti-inflammatory effect and the effective natural anti-inflammatory substances need to be found. In addition, the mechanisms of gingival inflammation should be elucidated. In this study, we tried to find out the mechanism of the gingival inflammation and effective natural anti-inflammatory substances with human gingival epithelial cells and Prevotella intermedia which is well known as a typical dental bacteria inducing gingivitis and periodontitis. In results, Prevotell intermedia initiated the gingival inflammation response by stimulating gingival epithelial cells to release an inflammatory cytokine, IL-8. Furthermore, the inflammation by Prevotella intermedia is related to COX-2, AP-1, and TNF-${\alpha}$ pathways. Green tea extract could effectively suppress the inflammatory responses induced by Prevotella intermedia. We find out the effective natural substance for the improvement of gum diseases by studying the mechanism of the gingival inflammation induced by dental bacteria.

• Journal of Life Science
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• v.31 no.12
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• pp.1072-1078
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• 2021

The oral pathogen Streptococcus mutans is considered a major causative agent of dental caries in humans. The use of dental hygiene products, including toothpaste and mouthwash, is used for caries control. However, food intake can lead to the recurrence of oral microorganisms. This study aimed to explore why this bacterium dies so quickly during prolonged incubation and to assess whether this growth characteristic is closely associated with the secretion of metabolic products. Notably, the number of live S. mutans cells rapidly declined after 24 hr during the entire period tested, whereas the number of Escherichia coli cells, an indicator strain, remained steady over the same period. To test whether the S. mutans supernatants contained possible signals that accelerated the death of neighbor cells, we obtained the individual supernatants at the above time points. Following pH neutralization, the cells in which the supernatant was supplemented with glucose grew well. However, pH adjustment alone could not fully recover cell growth in conditions in which the supernatant was supplemented, with or without glucose. These phenotypes of S. mutans may be associated with signaling, not only resulting from nutrient depletion. The findings on the survival phenotype of S. mutans provide new insights into cell-cell communication in the biology of this bacterium.