• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.70-79
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• 2020

Purpose: The purpose of this study was to evaluate the effect of attachments and palatal coverage on stress distribution in maxillary implant overdenture using finite element analysis. Materials and Methods: Four maxillary overdenture 3-D models with four implants placed in the anterior region were fabricated with computer-aided design. 1) Ball-F: Non-splinted ball attachment and full palatal coverage, 2) Ball-P: Non-splinted ball attachment and U-shaped partial palatal coverage, 3) Bar-F: Splinted milled bar attachment and full palatal coverage, 4) Bar-P: Splinted milled bar attachment and U-shaped partial palatal coverage. Stress distribution analysis was performed with ANSYS workbench 14. 100 N vertical load was applied at the right first molar unilaterally and maximum stress was calculated at the implant, peri-implant bone and mucosa. Results: The use of the ball attachment showed lower maximum stress on implant and peri-implant bone than the use of the milled bar attachment. But it showed contrary tendency in the mucosa. Regardless of attachment, full palatal coverage showed lower maximum stress on implant, peri-implant bone and mucosa. Conclusion: Within the limitation of this study, ball attachment improved stress distribution on implant and peri-implant bone rather than milled bar attachment in maxillary implant overdenture. Also, full palatal coverage is more favorable in stress distribution.

• Journal of Korean Clinical Health Science
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• v.5 no.1
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• pp.825-833
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• 2017

Purpose .This study aims to assess the influence factors on the level of satisfaction with hospital training and to provide basic data for more efficient hospital practice of students' public health administration . Methods . We have conducted a survey on students satisfaction with their hands on practice against 200 students in Busan, Kyeongnam and Kyungbook area, who have completed their practice in public health administration. We have identified the general characteristics of the target respondents, the current training status of the department for the hospital practice and training venue; also analyzed the characteristics composed of the apprentice student's attitude before the practice, satisfaction with the department training program and hospital for practice, as well as their practice at hospital. The general characteristics of the target respondents and clinic practice status at the hospital were measured in percentage and frequency analysis; the average and standard deviations of hospital size were also measured; and the correlations between satisfaction with the department, attitude towards the practice and satisfaction with the hospital were analyzed. Results . Most public health administration students experienced their practice at the hospital after the first semester on the $2^{nd}$year and they have received the foundation training for the practice. The survey allowed multiple responses and the results are as follows: medical terminology 49.5%, medical coordinator 36.7%, Hospital administration 26.5%, Health insurance 17.3%, and medical recording and practice 13.8% respectively. In terms of each individual student's attitude towards the practice at the hospital, the respondents answered as follows: I have completed the obligatory subjects for the practice before the practice 89.5%; I have been fully informed on the hospital for my practice. 74.5%; I responsibly practiced and worked with professionalism and sense of belonging to the hospital as a member of staff 90%; I have actively learned and adopted 95%; My knowledge and skills from the practice was relevant to the theory and practice from my course 83.5%. The findings of satisfaction by size of hospital were in order of a small clinic($3.24{\pm}0.63$), medium sized clinic($3.27{\pm}0.65$), hospital ($3.20{\pm}0.61$), and large sized comprehensive hospital ($2.93{\pm}0.74$). Consequently the satisfaction rate shows no significant difference by size of hospital. In relations between practice attitude and satisfaction with subject, the matter of acquiring information and fully understanding of the hospital for practice before practice(p=0.04), the matter of a sense of belonging and responsibility at hospital during practice(p=0.33). the matter of active adaptation attitude during practice (p=0.42), and the matter of correlations with school curriculum during practice(p=0.00) showed significant results. In relations between practice attitude and satisfaction with the hospital for practice, the matter of acquiring information and fully understanding of the hospital for practice before practice(p=0.01), the matter of a sense of belonging and responsibility at hospital during practice(p=0.04), and the matter of correlations with school curriculum during practice(p=0.00) showed significant results. Conclusion . The most essential subject for the practice in public health administration is medical terminology and there is no significance in satisfaction with the practice by size of hospital. Students were content with the hospital where they can experience as much as possible. Students content with their major show positive attitude towards the practice and so do those content with the hospital. Those with the positive attitude towards the practice show the high correlation of satisfaction with both the major and hospital. As a result, the satisfaction with the major is the significant attribute to the practice in the hospital.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.2
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• pp.25-31
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• 2019

Purpose: Metals induce metal artifact during CT-image for therapy planning, and it occurs images distortion, which affects the volumetric measurement and radiation calculation. In the case of using megavoltage computed tomography(MVCT), the volume of metals can be measured as similar to true volume due to minimal metal artifact outcome. In this study, radiation assessment was conducted by comparing teeth volume from images of kVCT and MVCT of head and neck cancer patients, then assigning to kVCT image to calculate radiation after obtaining the similar volume of true teeth volume from MVCT. Also, formal IR image was able to verify the accuracy of radiation calculation. Material and method: 5 head and neck cancer patients who had intensity-modulated radiation therapy from Radixact^® Series were of the subject in this study. Calculations of radiation when constraining true teeth volume out of kVCT image(A-CT) and when designated specific HU after teeth assigned using MVCT image were compared with formal IR image. Treatment planning was devised at the same constraints and mean dose was measured at the radiation assess points. The points were anterior of the teeth, between PTV and the teeth, the interior of PTV near the teeth, and the teeth where 5cm distance from PTV. Result: A difference of metals volume from kVCT and MVCT image was mean 3.49±2.61cc, maximum 7.43cc. PTV was limited to where the internal teeth were fully contained. The results of PTV dose evaluation showed that the average CI value of the kVCT treatment planning without the artifact correction was 0.86, and the average CI value of the kVCT with the artifact correction using MVCT image was 0.9. Conclusion: When the Treatment Planning was made without correction of metal artifacts, the dose of PTV was underestimated, indicating that dose uncertainty occurred. When the computerized treatment plan was made without correction of metal artifacts, the dose of PTV was underestimated, indicating that dose uncertainty occurred.

• Journal of Oral Medicine and Pain
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• v.31 no.2
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• pp.155-165
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• 2006

The purpose of this study was to evaluate treatment outcome and prognosis of the patients with orofacial pain disorders who visited for treatment in the Department of Oral Medicine, Dankook University Dental Hospital from January 2002 to December 2004. Orofacial pain disorders were categorized into TMD(myogenous, arthrogenous and muscle-joint combined TMDs), neuropathic pain disorder, oral soft tissue disease and complex condition simultaneously having more and two aforementioned categories and treatment period, method and treatment outcome were evaluated. The results of this study were as follows; 1. Average longevity of treatment period was the longest in the neuropathic pain, followed by soft tissue disease, complex conditions, arthrogenous TMD, muscle-joint combined TMD and myogenous TMD in order. 2. When treatment methods were largely categorized into pharmacologic, physical and oral appliance therapy, pharmacologic therapy was used the most frequently for the patients with neuropathic pain or oral soft tissue diseases, oral appliance therapy for those with arthrogenous TMD and physical therapy for those with myogenous TMD. 3. Of physical therapeutic methods used in our clinic, EAST and microwave was employed the most frequently in the patients with myogenous TMD, ultrasound for those with arthogenous TMD and LLLT for those with neuropathic pain or oral soft tissue disease. 4. In comparison with change of pain after treatment, there existed a tendency that pain from neuropathic pain disorders persisted while pain from TMD was getting better or totally disappeared. 5. Concerning the change of mouth opening range in the TMD subgroups, there was no significant difference among the subgroups but significant difference existed among opening ranges, indicating comfortable maximum mouth opening increased the most following treatment. Improvement of active range of mouth opening was the most considerable in those with disc displacement without reduction. It can be said on the basis of the findings from this study that various treatments currently used for the orofacial pain showed good results with TMD in regards with pain control and improvement of function, suggestive of favorable prognosis, while neuropathic pain or soft tissue disease was the clinical conditions difficult to resolve, requiring a long and persistent treatment.

• Journal of Oral Medicine and Pain
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• v.35 no.1
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• pp.61-73
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• 2010

The aim of this study was to investigate clinical assessment and cephalometric characteristics in 10s patients with condylar resorption, who visited in the Department of Oral Medicine Kyungpook National University Hospital at 2006, by use of panorama, transcranial view and lateral cephalometric radiograph. The results were as follows; 1. Clinical assessment 1) Total number of patients were 59. Female was 47 and male was 12, Females were predominant and patient's age ranged from 12 to 19. 2) Most of the patients had Grade II condyle resorption. 3) The number of who had Class I occlusion was 27, which was the largest group. The number of patients with openbite was 20. Average overjet was 3.58mm and average overbite was 0.97mm. 4) Most of the patients had parafunctional habit. 5) The patients of showing the pain in condylar resortion was 41 and the case of not showing the pain was 18. 6) Treatment duration of 23 patients were less than 1 month, 28 patients were treated with supported therapy. 2. Cephalometric Characteristics 1) A 16-year-old female patients showed smaller SNA, SNB and larger articular angle significantly as compared with those of normal group. 2) A 17-year-old female patients showed smaller SN, SAr, TPFH, ramus height and larger SN-GoMe, FMA, articular angle significantly as compared with those of normal group. 3) Over 18 years old female patients showed smaller SN, SNB, TPFH, ramus height and larger ANB, FMA, SN-GoMe, LAFH, articular angle, gonial angle significantly as compared with those of normal group. 4) Over 18 years old male patients showed smaller SN, TPFH, ramus height and larger FMA, SN-GoMe, LAFH, articular angle, gonial angle significantly as compared with those of normal group. 5) There was no significant difference between 10s and normal group in mandibular body length.

• Journal of Environmental Health Sciences
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• v.37 no.2
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• pp.102-112
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• 2011

Objectives: The purpose of this study is to analyze the effects of chronic exposure by welders to manganese (Mn) through an analysis of the degree of brain activity in different activities such as cognition and motor activities using the neuroimaging technique of functional magnetic resonance imaging (fMRI). The neurotoxic effect that Mn has on the brain was examined as well as changes in the neuro-network in motor areas, and the usefulness of fMRI was evaluated as a tool to determine changes in brain function from occupational exposure to Mn. Methods: A survey was carried out from July 2010 to October 2010 targeting by means of a questionnaire 160 workers from the shipbuilding and other manufacturing industries. Among them, 14 welders with more than ten years of job-related exposure to Mn were recruited on a voluntary basis as an exposure group, and 13 workers from other manufacturing industries with corresponding gender and age were recruited as a control group. A questionnaire survey, a blood test, and an fMRI test were carried out with the study group as target. Results: Of 27 fMRI targets, blood Mn concentration of the exposure group was significantly higher than that of the control group (p<0.001), and Pallidal Index (PI) of the welder group was also significantly higher than that of the control group (p<0.001). As a result of the survey, the score of the exposure group in self-awareness of abnormal nerve symptoms and abnormal musculoskeletal symptoms was higher than those of the control group, and there was a significant difference between the two groups (p<0.05, respectively). In the correlation between PI and the results of blood tests, the correlation coefficient with blood Mn concentration was 0.893, revealing a significant amount of correlation (p<0.001). As for brain activity area within the control group, the right and the left areas of the superior frontal cortex showed significant activity, and the right area of superior parietal cortex, the left area of occipital cortex and cerebellum showed significant activity. Unlike the control group, the exposure group showed significant activity selectively on the right area of premotor cortex, at the center of supplementary motor area, and on the left side of superior temporal cortex. In the comparison of brain activity areas between the two groups, the exposure group showed a significantly higher activation state than did the control group in such areas as the right and the left superior parietal cortex, superior temporal cortex, and cerebellum including superior frontal cortex and the right area of premotor cortex. However, in nowhere did the control group show a more activated area than did the exposure group. Conclusions: Chronic exposure to Mn increased brain activity during implementation of hand motor tasks. In an identical task, activation increased in the premotor cortex, superior temporal cortex, and supplementary motor area. It was also discovered that brain activity increase in the frontal area and occipital area was more pronounced in the exposure group than in the control group. This result suggests that chronic exposure to Mn in the work environment affects brain activation neuro-networks.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.750-756
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• 2008

Supernumerary teeth are frequently found in the anterior portion of the maxilla and develop as a result of abnormal proliferation of the dental lamina during tooth germ formation, caused by genetic or environmental factors. They may result in various complications, such as eruption interference, displacement, rotation of adjacent teeth, diastema, eruption into the nasal cavity, and development of dentigerous cyst. The optimal time for surgical extraction of supernumerary teeth has been a controversial issue. Someone prefer early surgical extraction because supernumerary teeth can cause eruption interference and displacement of adjacent teeth, eventually altering occlusion. Others prefer to delay surgical extraction until $8{\sim}10$ years of age in consideration of root maturation of the adjacent teeth and also patient's behavior. When surgical extraction of supernumerary teeth is postponed, there is possibility that impacted supernumerary teeth in the inverted or horizontal position move toward the nasal cavity, hard palate, or premolar area. When such intraosseous tooth migration is combined with the vertical growth of the maxilla, surgical approach becomes even harder. Therefore, possibility of intraosseous tooth migration should be considered as an important factor when deciding appropriate time for surgical extraction. We are presenting cases of mesiodens which showed intraosseous migration during $6{\sim}7$ years of follow-up period since the first diagnosis had been made at the $2{\sim}3$ years of age.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.249-257
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• 2007

State of problem : The use of zirconium oxide all-ceramic material provides several advantages, including a high flexural strength(>1000MPa) and desirable optical properties, such as shading adaptation to the basic shades and a reduction in the layer thickness. Along with the strength of the materials, the cementation technique is also important to the clinical success of a restoration. Nevertheless, little information is available on the effect of different surface treatments on the bonding of zirconium high-crystalline ceramics and resin luting agents. Purpose : The aim of this study was to test the effects of surface treatments of zirconium on shear bond strengths between bovine teeth and a zirconia ceramic and evaluate differences among cements Material and methods : 54 sound bovine teeth extracted within a 1 months, were used. They were frozen in distilled water. These were rinsed by tap water to confirm that no granulation tissues have left. These were kept refrigerated at $4^{\circ}C$ until tested. Each tooth was placed horizontally at a plastic cylinder (diameter 20mm), and embedded in epoxy resin. Teeth were sectioned with diamond burs to expose dentin and grinded with #600 silicon carbide paper. To make sure there was no enamel left, each was observed under an optical microscope. 54 prefabricated zirconium oxide ceramic copings(Lava, 3M ESPE, USA) were assigned into 3 groups ; control, airborne-abraded with $110{\mu}m$ $Al_2O_3$ and scratched with diamond burs at 4 directions. They were cemented with a seating force of 10 ㎏ per tooth, using resin luting cement(Panavia $F^{(R)}$), resin cement(Superbond $C&B^{(R)}$), and resin modified GI cement(Rely X $Luting^{(R)}$). Those were thermocycled at $5^{\circ}C$ and $55^{\circ}C$ for 5000 cycles with a 30 second dwell time, and then shear bond strength was determined in a universal test machine(Model 4200, Instron Co., Canton, USA). The crosshead speed was 1 mm/min. The result was analyzed with one-way analysis of variance(ANOVA) and the Tukey test at a significance level of P<0.05. Results : Superbond $C&B^{(R)}$ at scratching with diamond burs showed the highest shear bond strength than others (p<.05). For Panavia $F^{(R)}$, groups of scratching and sandblasting showed significantly higher shear bond strength than control group(p<.05). For Rely X $Luting^{(R)}$, only between scratching & control group, significantly different shear bond strength was observed(p<.05). Conclusion : Within the limitation of this study, Superbond $C&B^{(R)}$ showed clinically acceptable shear bond between bovine teeth & zirconia ceramics regardless of surface treatments. For the surface treatment, scratching increased shear bond strength. Increase of shear bond strength by sandblasting with $110{\mu}m$ $Al_2O_3$ was not statistically different.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.57-64
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• 2011

Purpose: The purpose of this study was to compare the cleansing performance of a distilled water, a diluted solution of sodium hypochlorite as a household bleaching cleanser and three alkaline peroxide cleansers in vivo plaque deposits by using scanning electron microscope. Materials and methods: Five individuals were selected from department of the prosthodontics in Pusan National University Hospital, and each of them was inserted with specimens for plaque accumulation in their temporary dentures for 48 hours. The specimens were removed and cleaned by each cleansing agents for 8 hours. Scanning electron micrographs were made from the specimens at a magnification of ${\times}2,000$. A panel of ten persons with a dental or paradental background, but not directly involved in the study, was selected to analyze the photomicrographs to determine which denture cleanser was more effective in removing plaque. Results: Diluted solution of sodium hypochlorite was the most effective at removing plaque following $Polident^{(R)}$, $Cleadent^{(R)}e$, $Bonyplus^{(R)}$ and distilled water in order. But there was no significant difference of cleansing efficacy between diluted solution of sodium hypochlorite and $Polident^{(R)}$, $Polident^{(R)}$ and $Cleadent^{(R)}e$, $Cleadent^{(R)}e$ and $Bonyplus^{(R)}$, respectively (P > .05). Alkaline peroxide cleansers by themselves cannot adequately remove accumulated plaque deposits, especially if the deposits are heavy. Corrosion could be seen on the surface of non-precious alloy specimens immersed in diluted solution of sodium hypochlorite. Conclusion: It is recommended to use of alkaline peroxide type cleansers with brushing whenever possible, since denture cleanliness is often poor due to the relative inefficiency of these cleansers.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.39-46
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• 2008

The purpose of this study was to assess the cariogenic potential of infant confectionaries. In vitro, as compaired with 10% sucrose solution and whole bovine milk. Buffering capability were determined by amount of 0.1N lactic acid consumed to titrate the 50ml specimen solutions to pH 4.0. The pH of the specimen solution inoculated by streptococcus mutans was measured by pH meter and the surface microhardness tester, before and after 48 hours incubation. The buffering capacity of infant confectionaries was higher than that of sucrose solution and lower than that of milk, and there were significant difference between infant confectionaries(p<0.05). The pH of infant confectionaries after 48 hours incubation was similar to 10% sucrose solution, and there were significant difference between infant confectionaries and milk(p<0.05). The microhardness change of primary tooth enamel of infant confectionaries group after 48 hours incubation was similar to that of 10% sucrose solution, and there were significant difference between infant confectionaries and milk(p<0.05). In conclusion, infant confectionaries seemed to have the ability to cause dental caries in primary teeth, and there were significant differences of cariogenic potential among infant confectionaries. Cooperative efforts of dentistry and manufacturers to reduce the cariogenic potential of infant confectionaries would be necessary to prevent the early childhood caries in children.