• The Korean Journal of Health Service Management
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• v.6 no.4
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• pp.205-217
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• 2012

A comparative study of the dental health perception and dental health behaviors among 12,325 middle and high school students in urban and rural areas was conducted by using "2010 National Dental Health Investigation". The results of this study are as follows. For the dental health perception and the utilization of dental service, all middle and high school students had a low perception of the their dental health status toward the farming and fishing regions from the urban. For the time of tooth-brushing among the dental health behaviors, most middle and high school students brushed their teeth after lunch. In connection with the frequency of cariogenic snack intake, high school students had a greater percentage toward the farming and fishing regions from the urban. For the dental health status, middle school students in big cities had a high average of carious permanent teeth, but high school students had a high average of carious permanent teeth toward the farming and fishing regions from the urban. In other words, there was no significant difference in missing permanent teeth, filling permanent teeth and decay permanent teeth between middle school students by region, but high school students had a greater percentage of the dental health perception and dental health behaviors toward the farming and fishing regions from the urban, showing a little difference. Consequently, there was a relationship between middle and high school students' perception of dental health and their behaviors of dental health.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.625-630
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• 2009

Root resorption of primary teeth usually occurs as the succeeding permanent teeth erupt, which induces differentiation of the hemopoietic cells into osteoclasts. Their root resorption pattern reflects the eruption path of the succeeding permanent teeth, and eventually the primary teeth shed as their succeeding permanent teeth erupt. Even when a permanent tooth germ is congenitally missing, root resorption of the corresponding primary tooth may still occur due to various factors, such as inflammation, traumatic occlusal force, and weakness of periodontium etc. Such congenital missing of permanent teeth is a commonly observed phenomenon in human be ing, and it often accompanies delayed retention of primary teeth. The etiologic factors for congenital missing in elude not only systemic diseases, but also local factors and human evolution process. In the radiographs of the cases in this report, the primary teeth without succeeding permanent teeth show pathologic root resorption. Root resorption progressed about 1/2~3/4 of the roots, and the surfaces of the resorption area were irregular. Considering high susceptibility of the periodontal ligament of primary teeth to root resorption, pathologic root resorption of primary teeth with delayed retention can be explained by the increased masticatory muscle force and abnormal occlusion developed during the mixed dentition. When the primary teeth without succeeding permanent teeth are lost, decision for space maintenance is required and long-term treatment plan for further prosthetic or orthodontic treatment should be establsihed.

• Restorative Dentistry and Endodontics
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• v.47 no.2
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• pp.24.1-24.15
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• 2022

Objectives: Regenerative endodontic treatment is a clinical procedure aimed at biologically regenerating damaged root canal tissue of immature permanent teeth. This study aimed to report the outcomes of regenerative endodontic treatment performed by endodontic postgraduate students. Materials and Methods: Clinical and radiographic data of 27 patients, aged 10-22 years, who underwent regenerative treatment of immature permanent teeth from 2015 to 2019 were followed up, wherein clinical and radiographic examinations were performed for each patient. Postoperative success rate and tooth survival were analyzed, and the postoperative radiographic root area changes were quantified. Results: A total of 23 patients attended the dental appointments, showing that all teeth survived and were asymptomatic. Specifically, 7 periapical pathosis cases were completely healed, 12 were incompletely healed, and 4 cases failed. Moreover, significant differences were found between discolored and non-discolored teeth, and between the presence or absence of periapical radiolucency. Additionally, 3 anterior teeth showed complete closure of the apical foramen, while the apical foramen width was reduced in 17 teeth and failed in 3 teeth. Root length was also found to have been increased in 7 anterior and 4 posterior teeth, and the average length ranged from 4.00-0.63 mm in the anterior teeth, 2.85-1.48 mm of the mesial root, and 2.73-2.16 mm of the molar teeth distal root. Furthermore, calcified tissue deposition was observed in 7 teeth. Conclusions: A favorable outcome of regenerative endodontic treatment of immature permanent teeth with necrotic pulp was achieved with a high survival rate.

• The Journal of the Korean dental association
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• v.56 no.4
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• pp.194-207
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• 2018

Objectives: The water fluoridation program has been implemented since 2008 at the Daesan water treatment plant, Changwon City. The aim of this study is to evaluate caries preventive effect of permanent teeth from community water fluoridation program Methods: Evaluation surveys were conducted on 8-, 10- and 12-year olds in the fluoridated and non-fluoridated area of Uichang-gu and Seongsan-gu, Changwon City in 2015. The number of the subjects in 2015 was 722 in fluoridated area and 707 in non-fluoridated area. The caries preventive effect of permanent teeth by community water fluoridation was estimated by the differences in adjusted DMFT and DMFS scores between the program and control groups. Cofounders of mean number of fissure-sealed teeth or surfaces, and number of subjects by gender were adjusted to estimate the caries preventive effect of permanent teeth. Results: The mean DMFT score or DMFS score of children aged 8-, 10- and 12-years adjusted for the number of fissure-sealed teeth or surfaces in fluoridated area were significantly lower than those in non-fluoridated area in 2015. The caries preventive effect of permanent teeth estimated based on the difference of mean DMFT scores adjusted for fissure-sealed teeth, age and number of subjects by gender between control and program group among children was 37.3%. Conclusions: These results suggest that the caries preventive effect of permanent teeth from water fluoridation program at Daesan water treatment plant, Changwon City was so high that the water fluoridation program should be developed in other regions in Korea.

• The Journal of the Korean dental association
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• v.11 no.5
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• pp.313-316
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• 1973

970 children visited attached hospital, S.N.U, were taken orthopantomograph. Of those children, there were 14 patients who have primary fused teeth. The author observed those cases and got following results. 1) Incidence of primary fused teeth was higher in female. 2) In the order of frequency, fused teeth of mandibular right primary lateral incisor and canine were 9 and that of mandibular left primary lateral incisor and canine were 4, and there was only one case in maxillary. 3) 13 cases showed the congenital absence of lateral incisor of the corresponding permanent teeth. 4) Incidence of fused teeth was 1.44%.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.333-338
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• 2008

Supernumerary teeth are characterized by an excess number of teeth, which can be responsible for a variety of irregularities in the primary and transitional dentition. Supernumerary teeth, especially in the maxillary anterior region, may prevent the eruption of adjacent permanent teeth and cause their ectopic eruption, diastema, root resorption, or formation of dentigerous cyst. Therefore, early diagnosis of supernumerary teeth is important for prevention of such complications, and adequate treatment should be given according to their location, number, and morphologic features. In this case, four supernumerary teeth in the maxillary anterior region were disturbing the eruption of adjacent permanent incisors. Two of them were located in proximity to the central incisor tooth germs that their immediate removal may injure the permanent tooth germs. In order to minimize such complications, surgical extraction of the four supernumerary teeth was performed in two stages. At first, only two inverted conical supernumerary teeth were extracted. The other two tuberculous supernumerary teeth, close to the permanent tooth germs, were extracted later after their natural dislocation. In that way, we could minimize affects on the neighboring permanent tooth germs and also the amount of alveolar bone removed during surgery.

• Journal of Korean society of Dental Hygiene
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• v.17 no.3
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• pp.331-342
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• 2017

Objectives: This study aimed at helping oral health prevention of the blind and related management plan, which is defined as the influence factors between missing and filled permanent teeth index and general feature and oral health behavior of the blind in Korea (estimates 229,678 persons) using data of the 6th Korea National Health and Nutrition Examination Survey from 2014 Korea Centers For Disease Control and Prevention. Methods: The blind over the age of 30 were selected as study subjects who have conducted health survey and dental inspections in KNHANES VI-2. Estimates of the subjects were 229,67 persons. For analyzing data, general linear models: GLM and covariance analysis were conducted to identify the relation between general feature and oral health behavior and missing and filled permanent teeth index. SPSS 21 statistical program was used, which is possible to conduct complex sampling design, and the significance level was 0.05. Results: The missing and filled permanent teeth index was 8.58 points. Regarding the results of the analysis, R-squared of the missing and filled permanent teeth index depending on general features of the blind was 0.839 points, which shows gender, age, residence, education level, individual income, disability rating, kinds of health insurance, marital status and recipient of basic living had an effect on the missing and filled permanent teeth index. R2 of the missing and filled permanent teeth index depending on oral health form of the blind was 0.728 points, which shows oral examination, dental treatment, smoking and toothbrushing after lunch had an effect on the missing and filled permanent teeth index. Conclusions: With the result of this study, we found the oral health actual condition of the blind in Korea. Therefore, it is considered that the government needs to introduce the personalized oral health education program to maintain oral health of the blind and to develop a program that uses braille and voice device which enables to access and utilize to improve oral health behavior that the government could use it as a reference to establish the policy plan.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.272-285
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• 2003

This study was conducted to observe the microscopic structures of cavities formed after ablation of primary teeth, permanent teeth, enamel and dentin in using a bur and cavities formed after ablation using laser and the following results were obtained after comparing the effects of ablation. Using a #330 bur and Er:YAG laser irradiated at 150 mJ, 200 mJ, 250 mJ and 300 mJ all at the frequency of 5 Hz, 1 mm enamel and dentin samples were ablated and the ablation time was measured. In order to measure the surfaces ablated, 5 each of primary teeth and permanent teeth were ablated using a #330 bur and Er:YAG laser at 150 mJ, 200 mJ, 250 mJ and 300 mJ for 1 sec and the cross section and vertical section were observed. The following results were obtained : 1. Cutting time of Er:YAG laser was longer than that of conventinal high-speed bur regardless of teeth type. 2. Cutting on enamel, Cutting time of conventional high-speed bur in deciduous teeth was longer than in permanent teeth(P<0.05). But Er:YAG laser was not showed any difference between the deciduous and permanent teeth(P>0.05). 3. Cutting on dentin, Cutting time of conventional high-speed bur in permanent teeth was longer than deciduous teeth. Er:YAG laser of 150 mJ, 5 Hz in permanent teeth was longer than in deciduous teeth(p<0.05). But laser of other power did not showed mean difference. 4. The cavity surface treated with the convetional high-speed bur revealed a relatively flat appearance, almost covered with a debris-like smear layer. Cavity wall showed striped appearance because of blade of bur. 5. The cavity surface treated by the Er:YAG laser system was irregular or rough surface with the absence charring, carbonization, or cracking of the dentin. In addition, there was an absence of a smear layer. Cavity floor was round and relatively smooth. According to these results, cutting time of Er:YAG laser was almostly same in permanent and deciduous teeth, but more effective in dentin than enamel. Cutting the sample, Er:YAG laser was needed more time than conventional bur. But SEM findings suggested that laser device produced favorable surface characteristic(i.e, no smear layer, irregular surface, cracking).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.215-219
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• 1992

The author ovserved a case of dentinogenesis imperfecta in a 8-year-old and a 9-year-old brother with complaints of abnormal morphologic changes of the teeth. 1. Clinically, yellowish brown colored teeth, fractured crown and numerous retained root tips of deciduous teeth with severe attrition were observed in the both deciduous and permanent dentitions. 2 Radiographically, small-sized teeth, partial or complete obliteration of the pulp chambers and pulp canals in the anterior teeth, partial obliteration of the pulp chambers and thin enamel in the permanent tooth germs were observed. 3. The familial history was their father has been lose his teeth early.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.133-135
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• 1996

This paper deals with the effect of teeth number variation in permanent Magnet DC motor. As teeth number varies, both flux density distribution and winding pitch are influenced, which is closely related to torque-speed characteristics, output power, and efficiency. In this study, motor design carried out using finite element method, and prototype motors were manufactured to test their performance analysis. In spite of torque ripple due to cogging effect better characteristic of machine using small teeth number was recorded than the motors with large number of rotor teeth. One of that reasons is caused by adopting large coil-length due to large number of teeth, i. e. large coil-pitch.