• The Korean Journal of Health Service Management
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• v.4 no.2
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• pp.63-72
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• 2010

The present study purposed to prevent oral diseases and to improve oral health in children. For this purpose, we selected 70 cases who are 5~7 years old preschoolers at the kindergarten affiliated to G College in Gyeongsangbukdo, and analyzed the general patterns of oral care and the relation of the patterns with dental plaque and deciduous dental caries in the children. Specifically, we conducted oral examination and applied pit and fissure sealant according to the eruption of deciduous molar and first molar. In addition, we executed the 1st and 2nd tooth brushing instruction (TBI), and surveyed S-OHI and PHP twice. Excluding 14 preschoolers who did not appear in the 2nd survey, we performed the study with 56 preschoolers and drew conclusions as follows. 1. The number of decayed or missed or filled teeth among deciduous teeth was 3 or more in 42.9% of female children, and 46.4% of male children, so male children showed a slightly higher rate. 2. The degree of dental plaque formation was $1.64{\pm}1.22$ among the surveyed children. 3. The oral health index was lower after TBI than before in all the children (P<.001). 4. Change in the oral health index was particularly larger in 7 year old female children (p<.005). 5. The patient hygiene performance index was lower after TBI than before in both the buccal surface and lingual surface of the children (p<.005). 6. The patient hygiene performance index was lower after TBI than before in all of male children's teeth except the right maxillary first deciduous molar (p<.001).

• International Journal of Stem Cells
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• v.16 no.1
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• pp.93-107
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• 2023

Background and Objectives: Chronic periodontitis can lead to alveolar bone resorption and eventually tooth loss. Stem cells from exfoliated deciduous teeth (SHED) are appropriate bone regeneration seed cells. To track the survival, migration, and differentiation of the transplanted SHED, we used super paramagnetic iron oxide particles (SPIO) Molday ION Rhodamine-B (MIRB) to label and monitor the transplanted cells while repairing periodontal bone defects. Methods and Results: We determined an appropriate dose of MIRB for labeling SHED by examining the growth and osteogenic differentiation of labeled SHED. Finally, SHED was labeled with 25 ㎍ Fe/ml MIRB before being transplanted into rats. Magnetic resonance imaging was used to track SHED survival and migration in vivo due to a low-intensity signal artifact caused by MIRB. HE and immunohistochemical analyses revealed that both MIRB-labeled and unlabeled SHED could promote periodontal bone regeneration. The colocalization of hNUC and MIRB demonstrated that SHED transplanted into rats could survive in vivo. Furthermore, some MIRB-positive cells expressed the osteoblast and osteocyte markers OCN and DMP1, respectively. Enzyme-linked immunosorbent assay revealed that SHED could secrete protein factors, such as IGF-1, OCN, ALP, IL-4, VEGF, and bFGF, which promote bone regeneration. Immunofluorescence staining revealed that the transplanted SHED was surrounded by a large number of host-derived Runx2- and Col II-positive cells that played important roles in the bone healing process. Conclusions: SHED could promote periodontal bone regeneration in rats, and the survival of SHED could be tracked in vivo by labeling them with MIRB. SHED are likely to promote bone healing through both direct differentiation and paracrine mechanisms.

• Journal of dental hygiene science
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• v.21 no.2
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• pp.127-132
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• 2021

Background: Obesity and dental caries have common risk factors such as food intake, eating habits, and lifestyle. Nevertheless, there has been no consensus on the significant association between obesity and dental caries, and additional studies are needed. We investigated the relationship between obesity and dental caries in some college students in this pilot study. Methods: Forty-two obese college students (body mass index [BMI]≥25) registered at a University Obesity Clinic and 19 normal students (18.5≤BMI<25) were recruited. Oral examinations were conducted, and anthropometric data and blood samples were collected. The blood concentrations of low-density lipoprotein (LDL), high-density lipoprotein, and triglyceride were also measured. After controlling for dental plaque index, a univariate analysis of dental caries indicators related to obesity was performed; partial correlation analysis was also conducted. A nonparametric test was used for the analysis of gender-related trends due to the limited number of participants. Results: The obese group had significantly fewer missing teeth (p=0.014), missing surfaces (p=0.035), filled surfaces (p=0.038), and decayed-missing-filled surfaces (p=0.020) than the normal group. There was no difference between the males in the normal and obese groups. The females in the obese group had significantly fewer missing teeth (p=0.003), missing surfaces (p=0.003), and decayed-missing-filled surfaces (p=0.046). Partial correlation analysis showed a weak negative correlation (r=-0.256) between the blood LDL concentration and decayed-missing-filled teeth. The other obesity and dental caries indicators were not correlated. Conclusion:The blood cholesterol concentration had a negative relationship with dental caries, and there were fewer cases of dental caries in the obese group in this study. However, it is important to clarify the relationship between obesity and dental caries through a dietary survey or additional investigations considering other confounding factors.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.775-787
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• 1996

The purpose of this study was to investigate the postnatal development of pulpal innervation with the tooth development and eruption process in developing rat mandibular molars (postnatal 1, 5, 10, 15, 20, 25, 35day-old and adult rats). Immunohistochemical method was carried out for the detection of nerve fibers, using the antibody against calcitonin gene-related peptide(CGRP). The results were as follows: The feature of CGRP-IR nerve fibers were shown in a bead-like appearance. The time of nerve entering into the dental papilla of tooth follicle began at the occured advanced dentinogenesis. The development of Raschkow plexus began at the formative stage of the roots and was accelerated at the stage of the crown emerged into the oral cavity. The number of nerve fibers entering the odontoblastic layer increased with the tooth eruption and mastication. The development of innervation was shown to be related with the stage of the development of individual teeth rather than the chronological age of the rat.

• Imaging Science in Dentistry
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• v.35 no.4
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• pp.199-202
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• 2005

Purpose : To report the incidence of radiological findings from screening panoramic radiographs and verify the validity of the panoramic radiography for screening purposes. Materials and Methods : Six thousand one hundred and sixty panoramic radiographs taken from the patients visiting the Health Promotion Center of CNUH were selected for this retrospective study. Panoramic radiographs were examined into the following pathologic conditions : the presence of periodontal bone loss, dental caries, periapical radiolucencies, retained roots, impacted supernumerary teeth, impacted third molars, odontoma, cystic lesions other than radicular cyst, sialoliths, and mixed radiolucent-radiopaque lesions. Number of pathologic conditions and Prevalence values were recorded. Results: The prevalences of pathologic conditions were $72.9\%$ of periodontal bone loss, $32.2\%$ of dental caries, $11.9\%$ of periapical radiolucencies, $10.8\%$ of retained roots, $0.4\%$ of root fracture, $1.0\%$ of impacted supernumerary teeth, $1.0\%$ of impacted third molars, $0.06\%$ of odontoma, $0.08\%$ of cystic lesion other than radicular cyst, $0.2\%$ of prolonged retention of deciduous tooth, $0.1\%$ of sialolith, and $0.04\%$ of mixed radiopaque and radiolucent lesion. Conclusion : Although the panoramic radiograph should not be used to replace intraoral radiographic and clinical examinations, this study showed that many dental pathologic conditions could be detected on panoramic radiographs. The panoramic radiograph might serve as a diagnostic aid in dental health evaluation programs.

• Journal of Periodontal and Implant Science
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• v.41 no.3
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• pp.143-148
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• 2011

Purpose: Few epidemiologic studies have investigated aggressive periodontitis in Koreans, but such studies of disease prevalence and other clinical characteristics would be invaluable in providing proper treatment. The aim of this study was to assess the prevalence of aggressive periodontitis and to measure the extent of associated periodontal breakdown. Methods: The study population consisted of 1,692 patients who visited the Department of Periodontology, Wonkwang Daejeon Dental Hospital from January to December, 2010. Clinical parameters (probing depth, gingival recession, periodontal attachment loss) were measured by a single examiner, and radiographic examination was performed at the baseline. Results: Twenty-eight (1.65%) patients showed clinical features of aggressive periodontitis, of which 27 patients exhibited the generalized form, and 1 exhibited the localized form. There was no significant difference between the percentage of male and female patients. The probing pocket depth of the maxillary first molar was deeper than that of the other teeth and gingival recession was also the most serious at the maxillary first molar. The periodontal attachment loss was the highest at the maxillary first molar. The average number of missing teeth was 1.29 per subject. Loss of the second molar was prominent. Conclusions: Within the limitations of this study, the periodontal breakdown evaluated by attachment loss was found to be most severe at the first molars of aggressive periodontitis patients. However, further large scale multicenter studies are necessary to access more precise data, including prevalence.

• Tribology and Lubricants
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• v.30 no.4
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• pp.212-217
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• 2014

A counter gear transmits the rotation angle, so the angular velocity ratio of the gear does not necessarily need to be constant in the meshing process. As a pinion has a small number of teeth when combined with an internal gear for counters, tooth interference can occur with the use of an involute curve. This paper introduces circular arcs that represent a tooth profile and fillet for the profile design of a pinion through the combination of arcs with lines. The straight line of a rack tooth represents the profile of a mating internal gear. Thus, the circular arc and line maintain contact during the rotation of the counter gear. This paper presents an analysis of the meshing of the circular arc tooth and rack tooth along with the properties of the counter gear, such as the change in rotational velocity and amount of backlash. The contact ratio of the counter gear is 1 because the tooth contact occurs between circular arcs and line. The initial position of tooth contact, which denotes the simultaneous contact of two teeth, is found. As the rotation of the pinion, only one tooth keeps the contact situation. This meshing property is analyzed by the geometrical constraints of the tooth profile in contact and the results are presented as graphical diagrams in which tooth-arc movements are superimposed.

• Imaging Science in Dentistry
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• v.45 no.4
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• pp.233-240
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• 2015

Purpose: This study investigated maxillary third molars and their relation to the maxillary sinus using panoramic radiography and cone-beam computed tomography (CBCT) Materials and Methods: A total of 395 maxillary third molars in 234 patients were examined using panoramic radiographs and CBCT images. We examined the eruption level of the maxillary third molars, the available retromolar space, the angulation, the relationship to the second molars, the number of roots, and the relationship between the roots and the sinus. Results: Females had a higher frequency of maxillary third molars with occlusal planes apical to the cervical line of the second molar (Level C) than males. All third molars with insufficient retromolar space were Level C. The most common angulation was vertical, followed by buccoangular. Almost all of the Level C molars were in contact with the roots of the second molar. Erupted teeth most commonly had three roots, and completely impacted teeth most commonly had one root. The superimposition of one third of the root and the sinus floor was most commonly associated with the sinus floor being located on the buccal side of the root. Conclusion: Eruption levels were differently distributed according to gender. A statistically significant association was found between the eruption level and the available retromolar space. When panoramic radiographs showed a superimposition of the roots and the sinus floor, expansion of the sinus to the buccal side of the root was generally observed in CBCT images.

• Journal of dental hygiene science
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• v.14 no.1
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• pp.7-14
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• 2014

This study aims to evaluate the impact of varying exposure to dental amalgam on urinary mercury levels in children by measuring the number of amalgam-filled teeth and the variance of mercury concentration in urine over a period of 2 years. A total of 317 (male 158, female 159) elementary school children (1st~4th graders) attending 2 schools in urban regions participated in this study. At 6-month intervals, 4 oral examinations were conducted to check any variance in the conditions of dental caries and the status of dental fillings. Also, urine tests were conducted followed by a questionnaire survey. To elucidate the factors potentially affecting the mercury concentration in urine, t-test, ANOVA, chi-square test and a mixed model were used for the analysis. Regarding the status of dental fillings in line with examination time periods, deciduous teeth had more amalgam-filled surfaces than those filled with resin, whereas permanent teeth had more resin-filled surfaces than those filled with amalgam. A significant relevance was found between the exposure to dental amalgam and urinary mercury levels. Specifically, subjects whose teeth surfaces had been filled with dental amalgam showed higher urinary mercury levels than those who had no dental amalgam fillings. Based on the analysis using the mixed model, the increase in the number of teeth surfaces filled with amalgam was found to be the factor affecting the increase in urinary mercury levels. The urinary mercury levels were found to be highly associated with the exposure to dental amalgam. The more the teeth surfaces filled with amalgam, the higher the urinary mercury levels. Hence, even a trace of dental amalgam fillings can liberate mercury, affecting the variance in the urinary mercury levels. These findings suggest that some criteria or measures should be developed to minimize the exposure to dental amalgam. Moreover, relevant further studies are warranted.

• The korean journal of orthodontics
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• v.2 no.1
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• pp.35-40
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• 1971

Since malocclusion affects a large segment of the population, it is by definition a public health problem. The etiology ana treatment of malocclusions have been studied by clinicians; however epidemioloic aspect of tile problem have been neglected. This study was undertaken using Angle's classification to obtain and to evaluate epidemiologic data on the prevalence of malocclusion in a group of 2,378 Yonsei University students, 17 to 23 years of age. All freshmen were selected, except for those students receiving orthodontic treatment and those few with too many missing teeth which prohibits classification by Angle's method. The following results were obtained: 1) Almost $91\%$ of students had malocclusion of the teeth severe enough to require correction. 2) There was a statistically significant difference in malocclusion between males and females($93.66\%$ malocclusion in males, $79.13\%$ malocclusioa in females). 3) Crowding was most pravalent in class I malocclusion. 4) There appeared to be a specific association between the number of lost first molars and Angle's classification. 5) In this study, more class II, Div.2 malocclusion appeared than in Massier's and Frankel's study of Caucasians, which used similar criteria. Class III malocclusion was more prevalent than normal occlusion in the Korean students studied, but in Caucasians' normal occlusion was more prevalent.