• Journal of Korean society of Dental Hygiene
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• v.11 no.5
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• pp.791-799
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• 2011

Objectives : This study aimed at examining the aspects of utilization of the dental services in some regions and analyzing the related factors with a view to helping the old solve the dental problems and overcome the difficulties. Methods : This investigation was intended for 422 old people living in Jeon-ju city and Jang-su county from July 18, 2006 to August 25 by direct interviewing posing questions. The survey data sets were analyzed by chi-square, correlation, multiple regression and logistic regression. Results : 1. The average number of the existing teeth per an old person was 13.6 and the 28.8% of the old who didn't use denture called for dentures. 2. The annual coefficient of utilization in dental services for an old person was 52.3% and the annual average visits to dental clinics were 3.12 days while 38.6% of the old experienced illegal dental treatments. 3. The affecting factors on the dental utilization for treatment were as follows: family income, dental clinics available, the number of existing teeth, the days of dental trouble, the recognition of the prevention of the dental disease, the knowledge for the dental treatment and the oral health judged by himself. 4. The major variables influencing the utilization of dental services were spouse presence, form of family, income, having a regular dental care, denture presence and the experience of inconvenience in living. Conclusions : To conclude, the following suggestions could be made. First, It was necessary that enforcement practice of free dental prosthesis service and application to the national health insurance in old people's prosthetic therapy for government support because the economic factor was barrier to utilization of the dental services. Second, Dental clinic was required to the health center because availability of common dental services was big impact in utilization of the dental services.

• Journal of Periodontal and Implant Science
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• v.33 no.3
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• pp.395-405
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• 2003

The purpose of this study was to examine the effect of smoking on the clinical, radiographic outcome of surgical peridontal therapy. The outcome of periodontal surgery was evaluated in 51 systemically healthy subjects that had received maintenance care. The study subject consisted of 26 smokers and 25 non-smokers. The average age of smoking patients was 51 years old and non-smoking patients was 48 years old. Changes of probing pocket depth(PPD) and radiographic bone height, and number of missing teeth compared between smokers and non-smokers during maintenance period after surgical therapy. The clinical parameters were less favorable in the smoking group compared with non-smoking group. The number and percentage of missing teeth were greater in smokers(21.6%) than non-smokers(l2.4%), especially in molars. The mean presurgery PPD was similar in smokers and non-smokers, molars and premolars, but significantly decreased at least 2 years after surgery. The mean PPD reduction was significantly greater in non-smokers than smokers. Both in the smoking and non-smoking group, the mean PPD reduction was significantly greater in premolars than molars. The radiographical evaluation was also less favorable in the smoking group than non-smoking group. The radiographic evaluation of bone height in smokers showed bone loss. On the contrary, bone height of non-smokers showed bone gain during the period of maintenance. But there was no significant difference between molars and premolars. The clinical and radiographic outcomes of the smoking group was less favorable than those of the non-smoking group. Therefore , smoking seems to influence on the clinical and radiographic outcomes of surgical periodontal therapy.

• Journal of Periodontal and Implant Science
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• v.52 no.3
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• pp.183-193
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• 2022

Purpose: We retrospectively analysed patients' dental and periodontal status according to the presence of non-communicable diseases (NCDs) and the effects of NCDs on periodontal treatment outcomes. Factors influencing disease recurrence were investigated using decision tree analysis. Methods: We analysed the records of patients who visited the Department of Periodontology, Pusan National University Dental Hospital from June 2014 to October 2019. As baseline subjects, 1,362 patients with periodontitis and who underwent full-mouth periodontal examinations before periodontal treatment were selected. Among them, 321 patients who underwent periodontal examinations after the completion of periodontal treatment and 143 who continued to participate in regular maintenance were followed-up. Results: Forty-three percent of patients had a NCD. Patients without NCDs had more residual teeth and lower sum of the number of total decayed, missing, filled teeths (DMFT) scores. There was no difference in periodontal status according to NCD status. Patients with a NCD showed significant changes in the plaque index after periodontal treatment. The decision tree model analysis demonstrated that osteoporosis affected the recurrence of periodontitis. Conclusions: The number of residual teeth and DMFT index differed according to the presence of NCDs. Patients with osteoporosis require particular attention to prevent periodontitis recurrence.

• Journal of dental hygiene science
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• v.10 no.4
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• pp.273-278
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• 2010

This study surveyed people with hearing impairments and speech defect living in an area of Gyeonggi-do using a self-administered questionnaire and interviewed them with a deaf interpreter's help during the period from January 21 to February 14, 2009 in order to investigate their oral health management attitude according to their general characteristics. The difference between males and females was statistically significant. The results of this study were as follows. 1. As to the number of times of tooth brushing according to gender, 62.5% of males and 34.2% of females brushed their teeth 2 times, and 25.0% and 35.4% 3 times. 2. As to experiences in scaling according to Academic qualification, those with high academic qualification had scaling more regularly 3. As to tooth brushing methods according to cohabitant, the rolling method was most common regardless of cohabitant. As to the number of times of tooth brushing according to residence type, 41.9% of those living with their parents brushed their teeth 3 times, and 69.2% of those living alone and 47.5% of married ones 2 times. 4. With regard to how to access oral hygiene management education, 81.1% of elementary school graduates used multimedia materials and sign language explanation and captions, 48.6% of middle school graduates used multimedia materials and sign language explanation and 14.3% multimedia materials and captions, 50.0% of high school graduates used multimedia materials and sign language explanation and 17.3% multimedia materials and captions. The parish for the buccal cavity hygiene managements of the hearing impairments speech defect and Development of an educational program are needed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.9
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• pp.116-121
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• 2020

In recent times, fuel economy enhancement and environmental regulation compliance have become the main topics of interest in the automobile industry. Electric vehicles are desirable alternatives to the existing cars that employ internal combustion engines. Specifically, electric vehicles are equipped with inverters, motors, and a gearbox instead of engines and transmission mechanisms. The gearbox is a key component, used to transmit power from the electric motor to the wheel. Therefore, the design of the gearbox is critical. However, most engineers design gears based only on their experience because no standards pertaining to the design factor exist, other than those for the gear ratios. To overcome this problem, the structural stabilities must be examined considering the design factors of the gears. In this study, we considered the module and number of teeth as the main factors. The constraints corresponded to the final gear ratio and fixed distance between each axle of the shafts. Moreover, a structural analysis was conducted, and the variation trend of the maximum equivalent stress against changes in the gear module and number of teeth was examined. By performing such an analysis, the structural stability in the design of a gear system could be effectively investigated.

• Journal of Oral Medicine and Pain
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• v.19 no.2
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• pp.181-192
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• 1994

There have been many different theories on the etiology of temporomandibular disorders(TMDs). The objective of the study was to investigate the effects of occlusal fctors and recent life event changes as prediposing fctor on the development of temporomandibjlar disorders. To evaluate the above predisposing factor, the author used T-scan system(Tekscan Co. U.S.A.) for quantitative occlusal analysis, clinical examination for occlusal state and Social Readjustment Rating Scale(SRRS) for recent life event change units (LCU). 63 patients with TMDs and 57 patients with malocclusion presented at Wonkwang University Dental Hospital participated in this study. The subjects were grouped by Angle's classification and presence of absence of TMDs and parafunctional oral habits. Data gained with regard to contact number, contact force, contact time, occlusal state(number of total teeth and occluding teeth, overjet, overbite) and occlusal interferences (protrusive posterior contact, nonworking side interference, and RCP-ICP slide) and recent life event changes. The data were processed and analysed by SAS statistical package program, The results of this study were as follows : 1. There were no significant differences on both quantitative occlusal contact analysis and occlusal state between TMDs group and Angle's malocclusion group. Also, there were no differences among the Angle's classifications. But amount of overjet in TMDs group were more greater than that of malocclusion group. 2. There was no difference on protrusive posterior contact, and balancing contact between TMDs group and Angle's malocclusion group. Premature contact was more frequent in malocclusion group, but RCP-ICP slide was more frequent in TMDs group. And RCP-ICP slide was more freqent in Angle's class II malocclusion than Angle's I or III malocclusion. 3. Life changes units in TMDs group were higher than those in malocclusion group. And recent life change units in group with parafunctional oral habit were higher than those in group without parafunctional oral habits. Clenching was the most common habit among parafunctional oral habits.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.504-509
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• 2006

Pediatric dentistry is differentiated from other fields of dentistry in that it provides comprehensive dental care for children and adolescents. In early days, pediatric dentistry used to be confined to the caries treatment and extraction of primary teeth However, the practice spectrum of pediatric dentistry has broadened to the orthodontic, surgical, esthetic and preventive treatments A survey that contained questions about practice patterns were mailed to 50 pediatric dentists, and 21 surveys were returned. Results were as follows: 1. The average number of patients per week was 82.4, and the average number of treated teeth per patient was 2.35. 2. Preventive treatments comprised 15.7%, restorative treatments 55.7%, endodontic treatments 15.6%, surgical treatments 10.5%, and orthodontic treatments 2.4%. 3. In restorative treatments, amalgam restoration comprised 3.8%, glass ionomer 5.5%, composite resin 63.0%, and stainless steel crown 27.7%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.185-192
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• 2014

Planetary gear design is complex because it involves a combination of discrete variables such as module, integer variables such as the number of teeth, and continuous variables such as face width and aspect ratio. Thus, an optimum design technique is needed. In this study, we applied a genetic algorithm to the design optimization of a planetary gear. In this algorithm, tooth root strength and surface durability are assessed with fundamental variables such as the number of teeth, module, pressure angle, and face width. With the help of this technique, gear designers could reduce trial and error in the initial design stages, thus cutting the time required for planetary gear design.

• Journal of Yeungnam Medical Science
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• v.40 no.4
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• pp.373-380
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• 2023

Background: The association between dental amalgam fillings and urine mercury concentrations was investigated in this study to assess the health risks associated with dental amalgams. Methods: This cross-sectional study included 99 women in their 20s who visited the dental clinic in Daegu, Korea. The 99 participants were composed of 68 subjects who had dental amalgam fillings (exposure group) and 31 subjects who did not have dental amalgam fillings (nonexposure group). Oral examinations were conducted by a single dental hygienist, sociodemographic features were investigated as confounding variables, and urine mercury concentrations were measured using an automatic mercury analyzer. Results: The mean±standard deviation of the urine mercury concentrations of the exposure and nonexposure groups were 1.50±1.78 ㎍/g creatinine and 0.53±0.63 ㎍/g creatinine, respectively. The exposure group showed significantly higher levels than the nonexposure group (p<0.01). The urine mercury concentration significantly increased with an increase in the number of teeth filled with amalgam, cavity surfaces involved, and number of defective amalgam fillings, and according to the latest exposure time (p<0.001). In the multiple regression analysis of amalgam-related factors and urine mercury concentrations after correction for confounding factors, the urine mercury concentration in the group with six or more amalgam-filled teeth, 11 or more cavity surfaces, and two or more defective amalgams was significantly higher than that in the nonexposure group (p<0.001). Conclusion: According to this study, exposure to dental amalgams was confirmed to significantly affect urine mercury concentrations.

• Journal of Periodontal and Implant Science
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• v.48 no.6
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• pp.337-346
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• 2018

Purpose: Peripheral artery disease (PAD) is a form of arteriosclerosis that occurs in the extremities and involves ischemia. Previous studies have reported that patients with periodontitis are at high risk for PAD. However, the relationship between these 2 diseases has not yet been fully elucidated. In this cross-sectional study, we investigated this relationship by comparing patients with PAD to those with arrhythmia (ARR) as a control group. Methods: A large-scale survey was conducted of patients with cardiovascular disease who visited Tokyo Medical and Dental University Hospital. We investigated their oral condition and dental clinical measurements, including probing pocket depth, bleeding on probing, clinical attachment level, and number of missing teeth; we also collected salivary and subgingival plaque samples and peripheral blood samples. All patients with PAD were extracted from the whole population (n=25), and a matching number of patients with ARR were extracted (n=25). Simultaneously, ARR patients were matched to PAD patients in terms of age, gender, prevalence of diabetes, hypertension, dyslipidemia, obesity, and the smoking rate (n=25 in both groups). Real-time polymerase chain reaction was performed to measure the bacterial counts, while the enzyme-linked immunosorbent assay method was used to measure anti-bacterial antibody titers and proinflammatory cytokine levels in serum. Results: PAD patients had more missing teeth ($18.4{\pm}2.0$) and higher serum levels of C-reactive protein ($1.57{\pm}0.85mg/dL$) and tumor necrosis factor-alpha ($70.3{\pm}5.7pg/mL$) than ARR patients ($12.0{\pm}1.7$, $0.38{\pm}0.21mg/dL$, and $39.3{\pm}4.5pg/mL$, respectively). Meanwhile, no statistically significant differences were found in other dental clinical measurements, bacterial antibody titers, or bacterial counts between the 2 groups. Conclusions: Our findings suggested that PAD patients had poorer oral and periodontal state with enhanced systemic inflammation.