• Journal of Korean society of Dental Hygiene
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• v.19 no.2
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• pp.317-327
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• 2019

Objectives: This study aimed to evaluate the effects of occlusion patterns using the T-scan $III^{(R)}$ system and oral parafunctional behaviors on temporomandibular joint disorder (TMD) in female college students. Methods: A questionnaire survey assessed TMD symptoms and oral behavioral checklist (OBC) scores in 120 female college students in their early twenties. Occlusion was evaluated using the T-scan $III^{(R)}$ system. Logistic regression analysis was performed to investigate the relationship between occlusion and OBC scores based on patients' symptoms of TMD and to determine whether OBC scores were a predictor of TMD. Results: A total of 101 participants with an average age of 22 (${\pm}2.17$) years were included in the analysis. The reported symptoms of TMD were categorized as moderate (28.8%), slight (27.7%), severe (25.7%), and asymptomatic (17.8%). Occlusion was analyzed using the T-scan $III^{(R)}$ system, and the mean occlusion time was 0.42(${\pm}0.5$) seconds. The results of logistic regression analysis showed that the group that would 'clench or grind teeth' during sleep showed an odds ratio for TMD that was 8.9 times higher than that in the group without this behavior. The group that would 'hold, tighten, or tense muscles without clenching' while awake showed an odds ratio for TMD that was 21.3 times higher than that in the group without this behavior. Conclusions: We confirmed that oral parafunctional behavior affects TMD. Therefore, we would like to continue studying the diagnosis and treatment of TMD by evaluating occlusion patterns and related OBC scores.

• Journal of Korean society of Dental Hygiene
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• v.19 no.3
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• pp.421-436
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• 2019

Objectives: The purpose of this study was to compare the dental treatment needs of workers depending on their shifts and working patterns. Methods: Only workers aged 15 or older according to the $6^{th}$ Korea National Health and Nutrition Examination Survey (2013-2015) were considered eligible. A total of 9,092 people who responded to health surveys and completed oral examinations and interviews were selected for the study. Statistical analysis was carried out by the complex samples general linear model. Results: As the daytime workers' age increased, the requirement for restorative treatment decreased. In contrast, the requirement for tooth extraction caused by dental caries and periodontal disease increased. As the evening shift workers' age increased, the requirement for restorative treatment decreased. In the case of shift workers, the requirement for restorative treatment was lowest in those aged 50-64 years and highest in those aged 30-49 years. In the case of smokers; the daytime workers required a higher amount of restorative treatment, pulpal treatment, and tooth extraction due to dental caries and periodontal disease; the night shift workers required a higher amount of restorative treatment; and the shift workers required a higher amount of tooth extraction caused by periodontal disease. The results of comparing the dental treatment needs depending on working patterns were: the need for restorative treatment was higher in night shift workers (0.377) than in shift workers (0.245); the requirement for pulpal and restorative treatment was higher in daytime workers (0.055) than in night shift workers (0.010); requirement for tooth extraction due to periodontal disease was higher in night shift workers (0.060) than in evening shift workers (0.012). Conclusions: There are differences in dental treatment needs depending on the workers' working patterns. Collective oral health care is needed at workplaces to promote the workers' oral health.

• Journal of Korean society of Dental Hygiene
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• v.22 no.4
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• pp.241-247
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• 2022

Objectives: This study aimed to determine the Missing Teeth (MT; mean number of missing permanent teeth) index experienced by year for adults between the ages of 19 and 64. Methods: This study was conducted by analyzing the raw data of participants in the 4th to 8th periods of the National Health and Nutrition Examination Survey (NHANES). For the statistical program, IBM SPSS / WIN 26 was used and an independent sample t-test was performed. Results: The average number of MT by year showed a decreasing trend. In 2007, 2008, 2010 and 2011, the average number of MT by sex was higher among females, and this was statistically significant (p<0.05). However, in 2019, males had a higher average number of MT than females, which was statistically significant (p<0.05). Conclusions: Males had a higher average number of MT than females in Korea, so it is considered that oral health programs or oral hygiene management according to sex are necessary.

• Journal of Korean society of Dental Hygiene
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• v.21 no.2
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• pp.183-191
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• 2021

Objectives: The purpose of this study was to identify the factors of satisfaction with regional oral health centers for people with disabilities in Korea. Methods: A survey was conducted with 784 patients who visited regional oral health care centers in Korea. A self-developed questionnaire (29 items) was adapted with a consent form and IRB (Institutional Review Board). All collected data were analyzed for statistics using SPSS version 25.0. Results: The study participants were 452 (57.7%) male patients, 207 (26.4%) aged 20-29 years old, and mostly had physical, developmental, and mental disabilities. The patients were introduced by their acquaintances, and the major reason for visit was specific dental care for the disabled. Most patients used their cars and took half to one hour to commute. The common factor affecting the comprehensive satisfaction was the facility satisfaction. Conclusions: A more comprehensive and standardized questionnaire should be developed for the annual evaluation of all centers. This study presents the basic data that can aid to activate the operation of the four oral health care centers for the disabled, which are scheduled to be implemented in the future, as well as 10 currently operated centers.

• Journal of dental hygiene science
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• v.22 no.3
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• pp.139-147
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• 2022

Background: Temporary crown resins are used prior to prosthesis placement, indicating the importance of aesthetics. The aim of this study was evaluate the color stability of various staining solutions according to the color of temporary crown resins using VITA Easyshade^Ⓡ V. Methods: The temporary crowns used were the powder-liquid type and included four shades. A total of 36 specimens were fabricated in the form of disks with a diameter of 1.8 mm and a depth of 2 mm. They were divided into four groups of nine each, and staining was performed for seven days by precipitation in 3 mL of three staining solutions composed of distilled water, black coffee, and red wine. Color and color stability evaluations were performed by a trained examiner using a digital spectrophotometer (VITA Easyshade^Ⓡ V). Color stability was analyzed using the ΔE value. Results: Because of the color stability evaluation using the ΔE value, the difference between three and seven days was significant in the specimen I and III groups (p<0.05). Further, post hoc analysis showed that the ΔE value of red wine was significant, indicating that the color stability in red wine was low. The ΔE values in group II between days three and seven were statistically significant (p<0.05). Post hoc analysis showed that distilled water, coffee, and wine had the highest ΔE values on day three. On day seven, the ΔE value for wine was significant, and the color stability was low. There was no significant difference in group IV according to the staining period and staining solution; therefore, color stability was high (p>0.05). Conclusion: This study showed that most temporary resin restorations exhibited color stability in the staining solution. The darker the color of the temporary resin restoration, the higher the color stability against extrinsic staining.

• The Journal of Advanced Prosthodontics
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• v.15 no.1
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• pp.44-54
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• 2023

PURPOSE. To assess the clinical performance of monolithic CAD-CAM lithium disilicate glass-ceramic (LDGC) crowns and metal-ceramic (MC) crowns provided by predoctoral students. This study also assessed the effects of patient and provider-related factors on their clinical performance as well as patient preference for these types of crowns. MATERIALS AND METHODS. Twenty-five patients who received 50 crowns (25 LDGC CAD-CAM and 25 MC) provided by predoctoral students were retrospectively examined. LDGC CAD-CAM crowns were milled in-house using the CEREC Bluecam system and cemented with either RelyX Unicem or Calibra Esthetic resin cements. MC crowns were cemented with RelyX Unicem cement. Clinical assessment of the crowns and the supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Patients' preference was recorded using a visual analog scale (VAS). The results were statistically analyzed using log-rank test, Pearson Chi-squared test and Kaplan-Meier survival analysis. RESULTS. Twelve complications were observed in the MC crown group (9-esthetic, 2-technical and 1-biological). In comparison, 2 complications in the LDGC CAD-CAM crown group were observed (1-technical and 1-esthetic). The 6-year cumulative survival rates for MC crowns and LDGC CAD-CAM were 90.8% and 96%, respectively, whereas the success rates were 83.4% and 96%, respectively. Overall, patients preferred the esthetic outcomes of LDGC CAD-CAM crowns over MC crowns. CONCLUSION. The high survival and success rates, low number of complications, and the high level of patients' acceptance of monolithic LDGC CAD-CAM crowns lend them well as predictable and viable alternatives to the "gold standard" MC crowns.

• Journal of the Korean Chemical Society
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• v.68 no.4
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• pp.185-190
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• 2024

Recently, it was reported that the benzobisoxazole (BBO) molecule can be used for independent modulation of the HOMO and LUMO energy levels. In this study, we utilized this interesting property of BBO to quantitatively investigate the substituent effects according the substituents. We designed and proposed four BBO model systems (1BBO, 2BBO, 3BBO and 4BBO) by extending the π-conjugation lengths based on a BBO molecule. Two directions of substitution (x-axis and y-axis) and 15 various substituents were considered. From strong correlation between the LUMO energy levels of x-axis substitution and HOMO energy levels of y-axis substitution calculated from DFT method, it is found that the standardization of substitution effects can be established from BBO model systems. In addition, we demonstrated that the HOMO values of y-axis substituted 3BBO show the best performance to define the order of substituent effects. Our proposed way can be used to expect the substituent effect of any arbitrary substituents and develop the organic sensors and organic light emitting diodes.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.485-497
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• 2003

Grapefruit seed extract has been reported to have antimicrobial effect. The purpose of this study was to evaluate the antimicrobial and anti-gingivitis effect of chewing gum containing grapefruit seed extract and xylitol. 40 healthy subjects with gingivitis or early periodontitis were divided into two groups. Subjects in the experimental group chewed gum containing grapefruit seed extract and xylitol while subjects in the control group chewed gum containing only xylitol. All subjects received scaling and tooth brushing instruction. 1 week after scaling was set as baseline. Gingival index and plaque index were scored at baseline, 1 week, 2 week, 3 week and 4 week. Bleeding index, probing pocket depth and clinical attachment level were scored at baseline, 2 week and 4 week. The number of total bacteria and Streptococcus mutans in unstimulated saliva of experimental group were counted at 1 week, 2 week, 3 week and 4 week. Gingival indices of experimental group and control group at baseline, 1 week, 2 week, 3 week and 4 week were 0.850${\pm}$0.298, 0.575${\pm}$0.345, 0.533${\pm}$0.332, 0.459${\pm}$0.311, 0.408${\pm}$0.224 and 0.758${\pm}$0.379, 0.592${\pm}$0.276, 0.563${\pm}$0.281, 0.454${\pm}$0.194, 0.413${\pm}$0.199 (mean${\pm}$SD), respectively. Plaque indices of experimental group and control group at baseline, 1 week. 2 week, 3 week and 4 week were 0.497${\pm}$0.500, 0.375${\pm}$0.484, 0.332${\pm}$0.471, 0,286${\pm}$0.452, 0.210${\pm}$0.407 and 0.411${\pm}$0.492, 0.375${\pm}$0.484, 0.354${\pm}$0.479, 0.313${\pm}$0.463, 0.193${\pm}$0.395, respectively. Bleeding indices of experimental group and control group at baseline, 2 week and 4 week were 0.377${\pm}$0.177, 0.298${\pm}$0.152, 0.192${\pm}$0.108 and 0.383${\pm}$0.124, 0.318${\pm}$0.153, 0.225${\pm}$0.126, respectively. Probing pocket depth of experimental group and control group at baseline, 2 week and 4 week were 2.56${\pm}$1.00, 2.40${\pm}$0.65, 2.23${\pm}$0.64 and 2.45${\pm}$0.682.37${\pm}$0.57, 2.19${\pm}$0.57, respectively. Clinical attachment level of experimental group and control group at baseline, 2 week and 4 week were 2.58${\pm}$1.01, 2.43${\pm}$0.67, 2.26${\pm}$0.65 and 2.49${\pm}$0.70, 2.40${\pm}$0.59, 2.22${\pm}$0.62, respectively. The % of reduction of total bacteria in saliva of experimental group at 2 week, 3 week and 4 week were 46 ${\pm}$ 53%, 53 ${\pm}$ 5% and 69 ${\pm}$ 33%. The % of reduction of Streptococcus mutans count in saliva of experimental group at 2 week, 3 week and 4 week were 52${\pm}$69%, 88${\pm}$30% and 89${\pm}$17%. From these findings, it can be concluded that regular use of grapefruit seed extract /xylitol chewing gum may be effective to control and prevent gingivitis and may have caries-preventive effect.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.54-61
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• 2000

Amalgam, though a widely used dental material, does not bond to the tooth substrate Therefore, retentive preparation of the cavity is necessary. Such amalgam restorations, until corrosion products form and plug the margin, will show significant marginal leakage. Unless this is prevented early on, saliva and bacteria may enter the cavity causing postoperative hypersensitivity, dissolution and collapse of the restoration, discoloration of the margin and secondary caries, leading to shortened life-span of the restoration and pulpal pathosis. Recently, a method of restoration has been introduced whereby tooth material can be preserved, cavity margin can be sealed and preventive treatment of pit and fissure can be administered while retaining all the advantages of conventional amalgam restorations. Such sealed amalgams involve removing the carious lesion without extending the cavity for prevention and using pit and fissure sealants to seal cavity margins and pit and fissures to reduce microleakage. In this study, finishing of the amalgam and sealant application were performed after different intervals following of amalgam restoration to compare the microleakage of sealed and conventional amalgam restorations. Thirty bicuspids were prepared with Class V cavity preparations on the buccal and lingual surfaces. After amalgam placement, they were divided into the following groups and treated accordingly. Group 1 : Polishing after 24 hours Group 2 : Immediate sealant application without polishing Group 3 : No polishing, but sealant applied after thermocycling 500 times After treatment, the samples were thermocycled 500 times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 30 seconds. After thermocycling, the samples were dipped into 1% methylene blue kept in a $37^{\circ}C$ incubator at 100% humidity for 24 hours. The teeth were then embedded in resin and cut bucco-lingually along the tooth axis and observed with a stereomicroscope to determine the degree of microleakage, The following results were obtained : 1. Group 2 showed the least microleakeage, while group 1 showed the greatest. 2. Group 1 showed significantly greater microleakage compared to group 2 (p<0.05). However, no significant differences were found between group 1 and 3(p>0.05). No significant differences in microleakage were also found between cup 2 and 3(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.408-419
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• 2007

In the child, it is very important that he/she will have the ability to suppress aesthetic restorative materials of secondary caries. With the representative preventive material against caries, the importance of fluoride is more emphasized. This study examined the differences in fluoride release and re-uptake among some restorative materials, following a treatment of APF gel and fluoride varnish. The surface roughness was observed under scanning electron microscope. Studying this will provide for the research to find effective restorative materials and fluoride type in tooth caries prevention. It is applied from presence at a clinic that restorative materials are resin, flowable resin, compomer and glass ionomer. Fluoride release was measured at 24-hour intervals for 7 days, 3-day intervals from 8th to 38th day using an ion-selective electrode and analyzer. Then, the materials were treated with the fluoride gel and fluoride varnish respectively, fluoride release was measured and specimens were evaluated under scanning electron microscope for 4 weeks. It was concluded that 1. Fluoride was released for 38 days from restorative materials under 1 ppm in case of flowable resin, 1-2 ppm in compomer and 2-8 ppm in glass ionomer, a few of fluoride was released after 45 days 2. Fluoride has more releasing after application of APF gel than fluoride varnish. Fluoride re-uptake was observed under 0.6-0.2 ppm in fluoride varnish and 0.6-2.6 ppm in APF gel after starting the procedure one day(p<0.05). For the remaining 4 weeks, they demonstrated a similar release. 3. Specimens were evaluated under scanning electron microscope. Applied fluoride in the experimental group surface was rougher than the control group that did not receive fluoride application. Fluoride varnish group had a smoother surface than both the APF gel group and the varnish APF gel group that received a fluoride application.