• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.266-272
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• 2009

Statement of problem: The number of edentulous patients is increasing due to an aging society, which leads to increased demands and interests on implant restorations. Implant restorations are an effective treatment method for both complete and partially edentulous patients, and the success rate has been reported to be high. But because of the increased use of implants in various situations have resulted in frequent reports of failures on implant restorations. Various efforts to overcome these failures have been made. Purpose: The aim of this study was to investigate the statistic survival rate of dental implants on patients who were treated at Dankook University Dental Hospital during the past 10 years based on their charts. Materials and methods :The research was made for two different periods of time; The first investigation was for patients from August, 1998 to August, 2003 and the second was for patients from September, 2003 to April, 2007. Information on the number of implants placed, the location and distribution of implants, the duration between the first and second surgery, and the survival rate of implants were investigated from the patients'charts. Results: 1. According to the first investigation, 1680 implants were placed on 612 patients and the second investigation showed 2438 implants placed on 933 patients. Thus a total of 4118 implants on 1545 patients. 2. Among the 1545 patients, 884 patients were male (57.2 %) and 661 patients were female (42.8%). Out of 4118 implants, 1739 implants (42.2%) were placed on the maxilla, and 2379 implants (57.8%) on the mandible. Implants were placed most frequently in the posterior region of the mandible. A total of 2043 implants (53.2%) were placed in this region. 3. According to the first investigation, 57 out of 1680, implants failed, while from the second investigation, 17 out of 2438 implants were reported as failure. In total, 74 implants failed, which results in a 98.2% survival rate. 4. The average duration between the first and the second surgeries in maxillas decreased from 7.4 months to 6.8 months. The duration also decreased from 5.6 months to 5.0 months in mandibles. Conclusion: As shown in the results, the number of placed implants and the survival rate of implants were higher in the second investigation than that of the first investigation. And the time spent after the first surgery to the second surgery was less in the second investigation. Consequently, it can be presumed that the demand and consumption of dental implants as well as the survival rate will increase in the future.

• Journal of dental hygiene science
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• v.8 no.4
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• pp.313-322
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• 2008

The purpose of this study was to examine the awareness of dental hygienists in different regions about credit bank system and their needs for that. The subjects in this study were 312 dental hygienists in dental hospitals and clinics in Seoul, Gyeonggi province, metropolitan cities, Gangweon province and Gyeongsang province. After a survey was conducted in 2008, the collected data were analyzed with SPSS 11.5 program. The findings of the study were as follows: 1. In regard to perception of the credit bank system, 68.3 percent of the dental hygienists were cognizant of that. The dental hygienists from most of the geographic areas were aware of it, but all the forty three dental hygienists from Gangweon province who accounted for 13.8 percent didn't know about that. As for media by which they acquired information on that, many of the dental hygienists learned about it from their acquaintances (46.2%), but that was not the case for the dental hygienists from Seoul and Gyeonggi province. 2. As for expectations for the credit bank system, those from Gyeongsang province had the greatest expectations for that in six out of nine items, which included academic or job performance improvement, acquisition of credits, degree or certificates and access to new technology. 3. Concerning educational spending on the credit bank system, 18.9 percent and 8.7 percent from Seoul/Gyeonggi province and Gangweon province spent less than 30 thousand won, and 19.9 percent from the metropolitan cities spent 30 thousand to less than 50 thousand won. 4. As for the importance of the categories of their major in the credit bank system, those from Gangweon province attached the most importance to oral health education ($3.56{\pm}1.259$), and the dental hygienists from the metropolitan cities put the most stress on preventive treatment ($3.64{\pm}1.191$).

• Journal of dental hygiene science
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• v.7 no.3
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• pp.121-127
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• 2007

The purpose of this study was to analyze college students basic knowledge of oral health of a college student and compare with the knowledge of oral health between dental hygiene students and non-dental hygiene students. A survey was conducted on the residents in Gyeonggi-do and Gwangju from June 2006 to May 2007. The findings of the study were as follows: 1. Concerning the knowledge of oral health, dental hygiene students got the source of information most frequently from school work about oral health(80.0%) and non-dental hygiene students got from health programs of TV or radio(42.7%). Concerning the reason of keeping of oral hygiene, dental hygiene students were to preventive of dental caries(80.9%) and nondental hygiene students were to preventive of periodontal disease(52.4%). There were significant difference between dental hygiene students and non-dental hygiene students(p < 0.001). 2. The knowledge degree of dental caries, to the both groups, methods of preventing caries appeared regular brush and main cause of dental caries was not to brush. There were significant difference between dental hygiene students and non-dental hygiene students(p < 0.001). 3. Dental hygiene students answered about the knowledge of fluoride know fluoride(93.6%) and non-dental hygiene students answered (55.3%). Dental hygiene students thought that fluoride could preventive dental caries(85.5%) but non-dental hygiene students thought that fluoride couldn't preventive dental caries(51.0%). There was significant difference between dental hygiene students and non-dental hygiene students(p < 0.001). 4. In the knowledge of oral health state, both of groups, replied that their own tooth state is average but they concerned about their tooth health. There was significant difference between dental hygiene students and non-dental hygiene students(p < 0.001). About main cause of dental caries, students ranked that the first reason was the poor toothbrush and the second reason was the over intaking of sugared foods. 5. About knowledge of oral diagnosis, to both groups, students ranked that first could endure the pain and the second was in much pain. For both groups, students ranked that difficult of dental treatment was cost, fear and time. There was significant difference between dental hygiene students and non-dental hygiene students(p < 0.01). For both groups, when they visit dentist's office, they felt misgivings and fear.

• Journal of dental hygiene science
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• v.17 no.6
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• pp.543-551
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• 2017

The purpose of this study is to analyze the experience of the parents who examined the first infant oral examination and to understand how to improve the practical oral examination business. In-depth interviews were held with 10 parents who did the first infant oral examination, and their children's age was less than 18 to 29 months. The following conclusions were obtained by deriving the concepts and categories of the recorded contents. First, the main reason for the unsatisfactory examination of this study was that it was formal. Parents were disappointed in the fact that they did not look at the mouth of the child at the same time as it was fast and they said because it is carried out free of charge, it is more formal than the examination for general dental treatment. Second, most of the participants questioned whether they should resume infant oral examination. Third, it appears that the tooth number or dental terminology in the result notice is difficult to understand. Fourth, the opinion on the improvement of the infant oral examinations was should provided that the oral health management information after examination and the direct oral health management method education at the examination. In addition, we identified the need for parents' oral health care education for infants. Therefore, it has been confirmed that in order for the infant oral examination and young children to be practically carried out, the problems should be improved by collecting opinions of the parents. Also it is necessary to search for efficient business management method through repeated research related to infant oral examination.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.603-616
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• 2007

Roy Huddle, having invented the coated particle in Harwell 1957, stated in the early 1970s that we know now everything about particles and coatings and should be going over to deal with other problems. This was on the occasion of the Dragon fuel performance information meeting London 1973: How wrong a genius be! It took until 1978 that really good particles were made in Germany, then during the Japanese HTTR production in the 1990s and finally the Chinese 2000-2001 campaign for HTR-10. Here, we present a review of history and present status. Today, good fuel is measured by different standards from the seventies: where $9*10^{-4}$ initial free heavy metal fraction was typical for early AVR carbide fuel and $3*10^{-4}$ initial free heavy metal fraction was acceptable for oxide fuel in THTR, we insist on values more than an order of magnitude below this value today. Half a percent of particle failure at the end-of-irradiation, another ancient standard, is not even acceptable today, even for the most severe accidents. While legislation and licensing has not changed, one of the reasons we insist on these improvements is the preference for passive systems rather than active controls of earlier times. After renewed HTGR interest, we are reporting about the start of new or reactivated coated particle work in several parts of the world, considering the aspects of designs/ traditional and new materials, manufacturing technologies/ quality control quality assurance, irradiation and accident performance, modeling and performance predictions, and fuel cycle aspects and spent fuel treatment. In very general terms, the coated particle should be strong, reliable, retentive, and affordable. These properties have to be quantified and will be eventually optimized for a specific application system. Results obtained so far indicate that the same particle can be used for steam cycle applications with $700-750^{\circ}C$ helium coolant gas exit, for gas turbine applications at $850-900^{\circ}C$ and for process heat/hydrogen generation applications with $950^{\circ}C$ outlet temperatures. There is a clear set of standards for modem high quality fuel in terms of low levels of heavy metal contamination, manufacture-induced particle defects during fuel body and fuel element making, irradiation/accident induced particle failures and limits on fission product release from intact particles. While gas-cooled reactor design is still open-ended with blocks for the prismatic and spherical fuel elements for the pebble-bed design, there is near worldwide agreement on high quality fuel: a $500{\mu}m$ diameter $UO_2$ kernel of 10% enrichment is surrounded by a $100{\mu}m$ thick sacrificial buffer layer to be followed by a dense inner pyrocarbon layer, a high quality silicon carbide layer of $35{\mu}m$ thickness and theoretical density and another outer pyrocarbon layer. Good performance has been demonstrated both under operational and under accident conditions, i.e. to 10% FIMA and maximum $1600^{\circ}C$ afterwards. And it is the wide-ranging demonstration experience that makes this particle superior. Recommendations are made for further work: 1. Generation of data for presently manufactured materials, e.g. SiC strength and strength distribution, PyC creep and shrinkage and many more material data sets. 2. Renewed start of irradiation and accident testing of modem coated particle fuel. 3. Analysis of existing and newly created data with a view to demonstrate satisfactory performance at burnups beyond 10% FIMA and complete fission product retention even in accidents that go beyond $1600^{\circ}C$ for a short period of time. This work should proceed at both national and international level.

• Progress in Medical Physics
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• v.24 no.4
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• pp.237-242
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• 2013

In the intracranial regions, an accurate delineation of the target volume has been difficult with only the CT data due to poor soft tissue contrast of CT images. Therefore, the magnetic resonance images (MRI) for the delineation of the target volumes were widely used. To calculate dose distributions with MRI-based RTP, the electron density (ED) mapping concept from the diagnostic CT images and the pseudo CT concept from the MRI were introduced. In this study, the look up table (LUT) from the fifteen patients' diagnostic brain MRI images was created to verify the feasibility of MRI-based RTP. The dose distributions from the MRI-based calculations were compared to the original CT-based calculation. One MRI set has ED information from LUT (lMRI). Another set was generated with voxel values assigned with a homogeneous density of water (wMRI). A simple plan with a single anterior 6MV one portal was applied to the CT, lMRI, and wMRI. Depending on the patient's target geometry for the 3D conformal plan, 6MV photon beams and from two to five gantry portals were used. The differences of the dose distribution and DVH between the lMRI based and CT-based plan were smaller than the wMRI-based plan. The dose difference of wMRI vs. lMRI was measured as 91 cGy vs. 57 cGy at maximum dose, 74 cGt vs. 42 cGy at mean dose, and 94 cGy vs. 53 at minimum dose. The differences of maximum dose, minimum dose, and mean dose of the wMRI-based plan were lower than the lMRI-based plan, because the air cavity was not calculated in the wMRI-based plan. These results prove the feasibility of the lMRI-based planning for brain tumor radiation therapy.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.2
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• pp.136-142
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• 2009

Bone density in the recipient implant site seems to be an important factor for long term success of endosseous implants. Preoperative evaluation of bone density is very helpful to assist the clinician with the treatment planning of implant therapy. Accurate information on bone density will help the surgeon identify suitable implant sites, thereby improving the success rate of the procedure. Purpose; The aim of this study was to evaluate a correlation between bone density measured preoperatively with computerized tomography and histologically measured bone density by bone biopsy. Patients and methods; Twenty seven patients were selected. All the patients were in good health, with no systemic disorder and additional bone graft. Preoperatively the patients underwent CT scanning to evaluate Houmsfield Unit(HU). Each patients wore a surgical template for implant placement. During surgery 2mm in diameter and 6mm in length specimens were taken. Histomorphometric analysis was performed using digitalized image analysis software Axiovision 4.3. Also, the Resonance frequency analysis(RFA) and insertion torque values were recorded. Results; The highest histomorphometric values was found in the posterior mandible $32.3{\pm}3.8$, followed by $29.9{\pm}2.6$ for the posterior maxilla, $29.4{\pm}2.6$ for the anterior maxilla, $28.6{\pm}2.3$ for the anterior mandible(p=0.214). The hounsfield unit was $989.2{\pm}258.1$ in the posterior mandible, $845.0{\pm}241.5$ in the anterior maxilla, $744.5{\pm}92.6$ in the anterior mandible, $697.3{\pm}136.9$ in the posterior maxilla(p=0.045). This results may suggest that there are strong correlation between the histomorphometric values and hounsfield unit(r=0.760, p<0.05). The RF measurements were $81.9{\pm}2.4$ ISQ in the posterior mandible, $79.0{\pm}1.4$ ISQ in the anterior mandible, $78.3{\pm}4.6$ ISQ in the posterior maxilla, $76.5{\pm}5.0$ ISQ in the anterior maxilla(p=0.048). The insertion torque values was $43.2{\pm}4.2\;Ncm$ in the posterior mandible, $42.0{\pm}0.0\;Ncm$ in the anterior mandible, $41.3{\pm}4.1\;Ncm$ in the posterior maxilla, $40.8{\pm}3.8\;Ncm$ in the anterior maxilla(p=0.612). This results may suggest that there are statistical significance between the hounsfield unit and the insertion torque values(r=0.494, p<0.05), the histomorphometric values and the insertion torque values(r=0.689, p<0.05). But there was no correlation between histomorphometric values and ISQ. There was no statistical significance in age and gender effect on parameters. Conclusions; There was significant correlations between bone density and implant stability parameters. The bone density measurements using preoperative CT may help clinicians to predict primary stability before implant insertion, which is associated with implant survival rates.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.111-126
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• 1998

In this study, radiographic evaluation was made using panoramic radiography and cross-sectional tomography of SCANORA/sup (R)/ in male and female adults in their 20's on the relationship between the maxillary sinus floor and the apex of the maxillary molar, to test the accuracy and effectiveness of the cross-sectional tomography, and to use this information in the assessment of preop. and postop. root canal treatment, apical surgery, extraction and implantology. Forty-one adults with an average age of 24.4 years were studied using panoramic radiography and cross-sectional tomography. In panoramic view and cross-sectional view, the position of the apices of maxillary molars were classified as separated, contacted, or protruded type; the general shape of the maxillary sinus floor was evaluated horizontally and vertically from cross-sectional tomography. The accuracy of each radiography was tested using maxilla from 5 fresh cadavers from the Anatomy Lab at Yonsei University Dental College, and panoramic view and cross-sectional tomography were taken in the same condition as with the patients. The results were as follows: 1. Panoramic view and cross-sectional view were taken in the maxilla specimen, and the actual distance between the maxillary sinus floor and the tooth apices were measured in the specimen; the median values of the distance from the tooth apices to the maxillary sinus floor in the panoramic view, cross-sectional view and in the actual maxilla specimen were 2.83 mm, 4.51mm, and 4.l5mm, respectively. In the cross-sectional view, the measured distance was close to the actual distance but in the panoramic view, the measured distance was far from the actual distance. 2. When the results of the panoramic view and cross-sectional view were compared, 40.5％ of the results agreed with each other in the two radiographic methods and buccal roots of the 2nd molar were the closest to the maxillary sinus floor in the cross-sectional tomography. 3. In cross-sectional view, when the vertical relationship of the maxillary sinus floor and maxillary roots was assessed, in 1st molars, type II (the sinus floor that extends down to the buccolingual furcation area) was predominant, while in 2nd molars, type I (the sinus floor located above the level connecting the buccal and lingual apices) was predominant. In the horizontal relationship, in 1st molars, type II (the lowest floor of the maxillary sinus located in between the buccal and lingual roots) was predominant; in 2nd molars, type I (the lowest floor of the maxillary sinus located on the buccal side of the buccal roots) and type II appeared in similar frequency. In conclusion, the SCANORA/sup (R)/ cross-sectional tomography was more effective than the frequently used panoramic view, in that the relationship of the maxillary molars and maxillary sinus floor can be evaluated more accurately and the buccolingual cross-sectional view can also be observed. And maxillary sinus floor that was close to maxillary 2nd molar had tendency to be located on buccal side than that close to 1st molar. Therefore, cross-sectional tomography is an effective and accurate method to evaluate the position of the teeth in relation to the sinus floor preoperative and can be easily used to diagnose localized periapical lesions. Also, the image quality obtained was quite satisfactory.

• Journal of agricultural medicine and community health
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• v.40 no.3
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• pp.158-170
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• 2015

Objective: The purpose of this study is to examine the effects of oral exercise on oral function and denture satisfaction of the elderly using dentures. Methods: The study was conducted with targets of the elderly in the 13 senior community centers in Cheongsong-gun, Gyeongsangbuk-do from September 2013 to April 2014. The study subjects were divided into two groups, the intervention group provided with 8 week oral exercise program and the control group without exercise. The data on oral function, denture satisfaction and oral health related quality of life (OHIP-14) were analyzed among the 79 subjects from the intervention group and the 71 subjects from the control group. Results: For oral function, salivary flow rate, mouth opening, pronunciation and salty taste were significantly improved in the intervention group (p<0.01). There were significant differences in salivary flow rate, mouth opening, pronunciation and salty taste between the two groups (p<0.01). For denture satisfaction, there were significant differences in masticatory function, fixing function, general treatment satisfaction and total denture satisfaction between the two groups (p<0.05). There were significant differences between the two groups in the total points of oral health related quality of life. Conclusion: Oral exercise was effective in improving oral function and denture satisfaction of the elderly using dentures. To improve oral health related quality of life of the elderly further researches and programs will be necessary.

• Journal of agricultural medicine and community health
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• v.36 no.4
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• pp.238-250
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• 2011

Objectives: This study was performed to investigate the service needs of the beneficiaries who had enrolled in home-based management programs for cancer patients. Methods: From March to May 2009, 676 cancer patients who were registered in home-based cancer patient management programs were selected as subjects for this study. The data were collected using a questionnaire along with a face-to-face interview performed by officers in charge of the home-based care programs of 47 regional health centers. Fifteen patients were excluded due to incomplete data, leaving 661 subjects who were ultimately enrolled in the study. Results: The mean age of subjects was $64.0{\pm}2.5$ years, and males comprised 45.1% (298/661) of the sample. The results of factor analysis for service needs showed that there were five main categories and Cronbach's alpha ranged from 0.593 to 0.890 for each factor. The service needs categories in order of importance were social support, information and education, psychological problems, physical symptoms and household chores. The service needs scores were significantly different when subjects were stratified by age, habitation, religion and disease classification. When we divided the subjects into complete remission, under treatment and terminally ill groups, the needs scores of the terminally ill patient group were significantly higher than those of the other groups (p<0.001). Conclusions: Service provision based on patient and beneficiary needs could be an effective intervention to reduce the economic burden of cancer management and to improve the quality of life of cancer patients receiving home-based care. Therefore, it is recommended that individual cancer patient care programs be developed and administered according to patient age, habitation and disease severity.