• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.263-290
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• 1997

Homogenization technique is employed to investigate the series of stress analyses of mandible for three different types of dental implants. This technique helps to make proper material model of bone and analyze such a non homogeneous structure at the level of individual microstructural unit. The stress analyses with homogenization technique show much higher stress level in the sponge bone, compared to those of conventional FEM. It also manifested that even a minor lateral force results in crucial stresses in the dental implant system and that the macroscale model should take the shape and size after real mandible to produce reasonable solution in the analyses of dental implant systems. The shapes of dental implants simulated in this study are rectangular-cross-sectioned type, hemi-sphere rooted type, and wedge type implant. The stress states of mandible with hemisphere rooted type implant and wedge type implant show similar levels, while those with sectioned rectangular implant results in higher stresses. It is suggested that the distance between the implant tip and cortical bone be kept far enough to prevent stress concentrations in the mandible.

• Journal of Korean society of Dental Hygiene
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• v.10 no.4
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• pp.595-605
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• 2010

Objectives : A precedent research has documented that occupational stress is closely associated with increased the risk of fatigue and decreased in job satisfaction. This study was conducted in an effort to assess the relationship of occupational stress to self-perceived fatigue and job satisfaction by using job strain model. Methods : The number of respondents was 122 dental hygienist who work in dental clinic and period of the investigation was July 2009 through september 2009. A structured questionnaire was employed to evaluate the participants' sociodemographics, job-related factors, health-related behaviors, occupational stress, job satisfaction and self-perceived fatigue. Occupational stress and self-perceived fatigue were assessed using the Korean Occupational Stress Scale-Short form (KOSS-SF) and the Multidimensional Fatigue Scale (MFS), respectively. Results : In job strain model, the ratio of Q2(High Strain Job) group that more susceptible to disease by stress than other group was 16% and the proportion of high fatigue group(Q3, Q4 group) and low job satisfaction group(Q3, Q4 group) was 48%, 45% respectively. In logistic regression analyses, a High Strain Job group was associated with higher odds of react factor(fatigue, job satisfaction) and the odds was down by 3.3%~7.5% after adjustment for age, smoking, alcohol drinking, regular exercise. So the effective strategy for fatigue, job satisfaction reduction for dental hygienist requires additional program focusing on innovated work environment that provide a enough leisure time and exercise program considering the personality traits. Conclusions : The results of this study suggest that occupational stress is a determinant predictor of self perceived fatigue and job satisfaction. Thus, a stress management program for the reduction of occupational stress, and the promotion of dental hygienist impact assessment health and quality of life is strongly recommended.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.187-197
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• 2013

PURPOSE. The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns. MATERIALS AND METHODS. Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a $45^{\circ}$ angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position. RESULTS. In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased. CONCLUSION. This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.526-543
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• 2000

Finite element analyses were performed to study effects on stress distribution generated in jaw bone for various shapes of dental implants: plateau type, plateau with small radius of curvature, triangular thread screw type in accordance with ISO regulations and square thread screw filleted with small radius partially. It was found that square thread screw filleted with small radius was more effective on stress distribution than other dental implants used in analyses. Additional analyses were performed on the implant with square thread screw filleted with small radius for very-ing design parameters, such as the width of thread end, the height of the thread of the implant and load direction, to determine the optimum dimensions of the implant. The highest stress concentration occurred at the region in jaw Pone adjacent to the first thread of the implant. The maximum effective stress induced by a 15 degree oblique load of 100 N was twice as high as the maximum effective stress caused by an equal amount of vertical load. Stress distribution was more effective in the case when the width of thread end and the height of thread were p/2 and 0.46p, respectively, where p is the pitch of thread. At last, using tensile force calculated from the possible insert torque without breading bone thread, finite element analysis was performed on the implant to calculate pre-stress when the primary fixation of the implant was operated in jaw bone. The maximum effective stress was 136.8 MPa which was proven to be safe.

• Korean Journal of Computational Design and Engineering
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• v.7 no.1
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• pp.27-33
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• 2002

MDO(Multidisciplinary Design Optimization) methodology is a new technology to solve a complicate design problem with a large number of design variables and constraints. The design of a dental implant system is a typical complicate problem, and so it requires the MDO methodology. Actually, several analyses such as rigid body dynamic analysis and structural stress analysis etc. should be carried out in the MDO methodology application to the design of a dental implant system. In this paper, as a first step of MDO methodology application to the design of a dental implant system, the impact force which is applied on the tooth in masticating is calculated through the rigid body dynamic analysis of upper and lower jaw-bones. This analysis is done using ADAMS. The impact force calculated through the rigid body dynamic analysis can be used for the structural stress analysis of a dental implant system which is needed for the design of a dental implant system. In addition, the rigid body dynamic analysis results also show that the impact time decreases as the impact force increases, the largest impact force occurs on the front tooth, and the impact force is almost normal to the tooth surface with a slight tangential force.

• The Journal of the Korea Contents Association
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• v.21 no.1
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• pp.352-362
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• 2021

This study was conducted to investigate the relationship between major satisfaction, depression, self esteem and life stress among college dental hygiene students. This study targeted 227 dental hygiene student in one school. Data were analyzed using descriptive analyses, t-tests, ANOVA, Pearson's correlation, and Hierarchical multiple regression with the SPSS WIN 21. program. The results of this study were as follows: The average score of major satisfaction was 3.65±.59, the score of depression was 1.74±.43, the score of self esteem was 3.59±.70, the score of life stress was 1.50±.33. Life stress was negatively related to major satisfaction and self esteem, and positively related to depression. The factors influencing the life stress of dental hygiene students were grade, economic status, major satisfaction, depression. Overall, to decrease life stress among dental hygiene student, it is necessary to develop educational method and program that can prevent and mitigate depression and can increase major satisfaction.

• Journal of dental hygiene science
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• v.13 no.4
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• pp.440-448
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• 2013

The purpose of this study was to analyze the effects of perceived stress on dietary habits and oral health behaviors in Korean adolescents. Data were from the Korea Youth Risk Behavior Web-based Survey (KYRBS) in 2011. A total of 74,186 adolescents were surveyed using the self-administered questionnaire. Logistic regression analyses were performed to elucidate the effects of perceived stress on dietary habits and oral health behaviors. Statistical analyses were conducted, and p<0.05 were considered significant. We found that adolescents with higher stress were more likely to increase the risk of adverse dietary habits (low consumption of fruits, vegetables and milk, high consumption of carbonated soft drinks, fast food and cookie) compared to those with lower stress. Regarding the relationship between perceived stress and oral health behaviors, adolescents with higher stress were less likely to practice oral health behaviors such as brushing teeth after snack consumption and brushing teeth before sleep compared to those with lower stress. This result indicates that adolescents' perceived stress might play a significant role in the negative dietary habits and oral health behavior.

• The Journal of Korean Society for School & Community Health Education
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• v.22 no.4
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• pp.39-48
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• 2021

Objectives: The purpose is to prepare measures to effectively improve college life adaptation by identifying relevance between interpersonal relation disposition and college life adaptation, college life stress and college life adaptation for dental hygiene students. Methods: 375 dental hygiene students attending some local universities in Gyeonggi-do were sampled for convenience. The results of this study are as follows. Results: First, As a result of interpersonal relation disposition according to general characteristics, superiority-dominance tendencies were higher in first and third graders, in groups with grades above 4.0 and groups with lower subjective economic levels. And the stress of college life was high for second graders and students with lower grades than 2.0. Second, According to the correlation between factors, governance-dominance, independence-responsibility, sympathy-acceptance, sociable-friendliness, and ostentation-intoxication of interpersonal tendency factors had proportional relationship with college life adaptation, rebellion-distrust and college life stress had inverse relationship. Third, The results of multiple regression analyses to identify factors that affect college students' adaptation to college life were in the order of stress in college life, first grade, sociable-friendliness, second grade, rebellion-distrust. Conclusion: In order to improve college life adaptation, counseling and practical mediation programs should be developed and applied to effectively manage and control the negativity and positivity implied by interpersonal relationships and college life stress.

• Journal of Korean society of Dental Hygiene
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• v.17 no.3
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• pp.449-463
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• 2017

Objectives: The objective of this study was to identify the relationship between emotional labor and occupational stress of the dental hygienists, and the effects of emotional labor on their occupational stress and health problems including depression, anxiety and sleep. Methods: The survey was conducted using the questionnaires about dental hygienists' working in medical institutions in Busan, Gyeongsangnam-do from August 19th and October 7th, 2016. Total of 225 participants were selected for data analyses. Frequency analysis, t-test, ANOVA, Pearson's correlation coefficient analysis, and regression analysis were conducted using SPSS Windows ver. 21.0 program(SPSS Inc., Chicago, IL. USA). Results: The analysis of the factors affecting emotional labor, occupational stress, anxiety, and sleep by participants' characteristics showed that those with higher education level, work position and annual salary had higher emotional labor. In addition, participants who worked 5 days every other week and were responsible for patient consultation had higher emotional labor. The analysis of correlations among emotional labor occupational stress, anxiety, and sleep showed positive correlations between emotional experience and emotional expression, occupational stress and emotional expression, and anxiety and emotional expression. On the other hand, negative correlation was found between anxiety and emotional experience. Regression analysis was conducted to examine the effect of emotional labor on job stress. Emotional labor was a factor affecting job stress and anxiety. Conclusions: In order to improve emotional control and vulnerability to stress among dental hygienists, intra-organizational training opportunities and mental health care strategies are needed. Additional broad-based studies are required to identify the factors affecting the occupational stress and emotional labor and to develop relevant intervention measures.

• Journal of dental hygiene science
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• v.19 no.4
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• pp.271-278
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• 2019

Background: This study aimed to examine the factors that influence clinical performance of dental hygiene students to provide useful data for developing strategies to improve clinical competence. Methods: The effects of variables on clinical competence by quantile level were analyzed using quantile regression analysis in 247 dental hygiene students. Quantile regression and multiple regression analyses were conducted using the Stata 11.0 program to analyze predictors of clinical competence. Results: The clinical competence score of dental hygiene students was 42.69±5.90, the satisfaction of clinical practice was 49.90±7.44, the clinical practice stress was 50.62±7.37, and the professional self-concept was 31.68±4.41. Empathy was the highest at 50.87±4.93. Multiple regression analysis showed that school year, stress from clinical training, satisfaction with clinical training, professional self-concept, and empathy had significant impact on clinical competence. Quantile regression analysis showed that the effects varied depending on the clinical competence level. School year and professional self-concept had a significant positive effect, regardless of the clinical competence level, while empathy had a significant positive effect at the top 10% (Q90) of the clinical competence level. Satisfaction with clinical practice affected clinical competence at Q25, Q50, and Q90. Stress from clinical practice had significant effects at Q25, Q50, and Q90 (p<0.05). Conclusion: According to the study results, different factors affected clinical competence according to the quantile of clinical competence. This study provides valuable implications for designing clinical competence enhancement programs and strategies. In addition, objective indicators for considering factors that may affect the clinical competence, such as academic competence and satisfaction of practice hospitals, are expected to require detailed analysis and measures.