• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.788-794
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• 1997

As one of the developmental disturbance in shape of teeth, a twinning has very rare frequency in permanent teeth. Because it is possible to diagnose the twinning by use of the radiograph, it is very important to detect this anomaly early by careful examining the radiographs. The twinning produces several orthodontic problem such as crowding, protrusion, ectopic eruption of adjacent teeth. Therefore it is necessary, in proper time, the extraction and orthodontic treatment should perform.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.882-884
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• 2000

This paper deals with the effect of teeth width variation in Permanent Magnet DC motor. As teeth width varies, effective flux density is influenced, which is closely related to torque-speed characteristics, output power, and efficiency of the motor. In this study. motor design was carried out using finite element method with various teeth width. Prototype motors under constraints of same armature diameter, material and axial length were made and their performances were tested.

• Journal of Magnetics
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• v.16 no.3
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• pp.281-287
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• 2011

The stationary discontinuous armatures that are used in permanent magnet linear synchronous motors (PM-LSMs) have been proposed as a driving source for transportation systems. However, the stationary discontinuous armature PM-LSM contains the outlet edges which always exist as a result of the discontinuous arrangement of the armature. For this reason, the high alteration of the outlet edge cogging force produced between the armature's core and the mover's permanent magnet when a mover passes the boundary between the armature's installation part and non-installation part has been indicated as a problem. Therefore, we have examined the outlet edge cogging force by installing the auxiliary teeth at the armature's outlet edge in order to minimize the outlet edge cogging force generated when the armature is arranged discontinuously. Moreover, we obtained the calculation by analyzing the shape of the auxiliary teeth in which the outlet edge cogging force is minimized the most.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.11-19
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• 2017

The purpose of the study was to investigate the distribution of primary fused teeth and identify the correlation between primary fused teeth and their effect on permanent dentition. 2575 children between the age of 4 and 6 in Kyungpook National University Hospital from January 2009 to August 2015 were investigated. A total of 84 children (46 boys and 38 girls) had fused teeth. 14 of these children had two fused teeth. Prevalence of caries involvement was in 65% of maxilla and 6% of mandible. Prevalence of permanent successors missing was 86.3% in the cases involving maxillary central and lateral incisor, 70% in mandibular lateral incisor and cuspid, 11.7% in mandibular central and lateral incisor. 27 of 84 children (32.1%) had supernumerary teeth. The highest prevalence rate is seen in the cases involving maxillary central and lateral incisor. Delayed permanent tooth eruption was only observed in the maxilla because of developing supernumerary tooth. Early diagnosis of fused tooth in the primary dentition can allow the dentist to make treatment plan at the appropriate time in accordance with the tooth arrangement and tooth development.

• Journal of Korean Academy of Oral Health
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• v.41 no.4
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• pp.296-302
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• 2017

Objectives: The water fluoridation program has been implemented since 2008, in a region of Geoje City. This study aimed to evaluate the effectiveness of the water fluoridation program on caries prevention in the permanent dentition. Methods: Evaluation surveys were conducted on 8-, 10- and 12-year-old children in the fluoridated and non-fluoridated regions of Geoje City, in 2015. The survey included 834 children from the fluoridated regions and 703 from the non-fluoridated regions. The data obtained from the survey were analyzed using the IBM SPSS statistical package version 23.0. The effectiveness of community water fluoridation in caries prevention was estimated by the differences in the decayed, missing, filled teeth (DMFT) and decayed, missing, filled surfaces (DMFS) scores, between the program and control groups. The mean numbers of fissure-sealed teeth and surfaces were adjusted to reduce their confounding effect. Results: The mean DMFT and DMFS scores (0.69 and 0.91, respectively) of 10-year-olds from the fluoridated regions, after adjusting for the numbers of fissure-sealed teeth and surfaces, were significantly lower than those of the 10 year olds (DMFT: 0.95, DMFS: 1.32) from the non-fluoridated regions. The effectiveness of water fluoridation on caries prevention in the permanent dentition, estimated based on the differences in the mean DMFT and DMFS scores, adjusted for the number of fissure-sealed teeth and surfaces, between the program and control groups of 10-year-old children, was 27.4% and 31.1%, respectively. Conclusions: These results suggest that the effectiveness of water fluoridation on caries prevention in the permanent dentition, in Geoje City was so high that this program should be implemented in other regions in Korea as well.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.771-775
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• 1997

Ectopic eruption is defined as abnormal eruption and results in malpositioned teeth and abnormal root resorption of adjacent teeth. Ectopic eruption, first reported by Chapman, occurs in 3% of the population and that mostly in the maxilla. Etiologic factors include narrow maxilla, large maxillary teeth, retarded calcification of the first molar, inclined eruption path of the first molar and retruded position of the maxilla. Impaction of the second molar is rare and occurs mostly in the mandible. Major causes are large teeth and insufficient arch length. Halterman has devised a method of distalizing a ectopically erupting first molar by cementing a band on the second deciduous molar with a hook soldered and a button bonded to the occlusal surface of the first permanent molar. Ectopically erupted posterior teeth should be treated early to maintain normal development of the dentition, harmony of facial growth and occlusal support, a failure to do so could result in severe malocclusion, periodontal damage and continued root resorption of the adjacent teeth. Early detection and treatment is thus vital. The author is submitting this report as he has obtained favorable results in treating a patient who came to the SNUDH Dept. of Pediatric Dentistry complaining of the first molar by using a modified Halterman appliance.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.795-804
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• 1997

Developmental dental morphological anomalies are fusion, gemination, twinning, concrescence and etc. They may cause many problems in conservative, periodontal and esthetic aspects. Fusion is a condition where two separate tooth buds unite at some stage in their development to form a bifid crown. If tooth contact occurs early, at least before the start of calcification, the two teeth may be completely unites to form a single large tooth. If tooth contact occurs after the time when a portion of the tooth crown has completed its formation, there may be union of the roots only. In fusion the dentin is always confluent. Fusion teeth is more common in the deciduous than in the permanent dentition. Fused teeth are relatively rare, and are mostly mandibular anterior teeth. Fusion of normal and supernumerary teeth or between normal teeth may occurs. The exact etiology factor of fusion is unknown, but genetic and environmental factors seems to be related. A variety of complications and subsequent treatments have been suggested on this teeth. Periodontal conditions may arise due to a groove formed at the line of fusion of the two teeth. Crowding or Protrusion with potential for malocclusion or delayed eruption of adjacent teeth. Fusion teeth appear in the anterior region, they usually cause esthetic problems. Treatments vary depending on the problem, the location, and the extent of fusion. Treatment of fused teeth has been reported from endodontic, orthodontic, periodontic, surgical and multidisciplinary. This report presents the esthetic improvements by separation of two clinical crowns. Bone reduction or endodontic treatments are not required.

• Journal of Korean society of Dental Hygiene
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• v.18 no.6
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• pp.921-932
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• 2018

Objectives: The aim of this study was to investigate the number of existing permanent teeth and the denture usage status in elderly adults aged 65 years and above living in metropolitan cities and to confirm the degree of oral health inequality caused by the differences in oral conditions in each metropolitan city using the Lorenz curve and the Gini coefficient. Methods: The raw data for the analysis were obtained from the dataset of the sixth Korea National Health and Nutrition Examination Survey conducted between 2013 and 2015. The subjects included 1,764 people who underwent oral examination and answered questions. The complex samples general linear model was used to analyze the number of existing permanent teeth adjusted for age and monthly household income. The proportion of edentulousness and the denture status was analyzed using complex samples crosstabs. Results: The number of existing permanent teeth in the elderly adults aged 65 years and above was lowest in Ulsan (15.41) and highest in Gwangju (20.44). The proportion of edentulousness was highest in Busan (14.5%) and lowest in Daejeon (4.0%). With regard to the proportion of denture users, Busan had the highest tendency for denture usage (50.4%) and Gwangju had the lowest tendency (34.9) (p=0.172). The Gini's coefficient for the number of existing teeth was lowest in Busan (0.332). Oral health inequality was most severe in metropolitan cities. Conclusions: We found that oral health inequality exists among elderly adults living in the metropolitan cities of Korea using the Lorenz curve and Gini's coefficient.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.447-453
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• 2007

The purpose of this study was to investigate the relationship between morphology and number of deciduous teeth and the occurrence of other dental anomalies in their successors, and to evaluate the necessity of early diagnosis of dental anomalies in the primary dentition. Prevalence of double teeth and congenital missing teeth was investigated in 254(134 boys, 120 girls) panoramic radiographic films, taken by 2 to 7-year-old children in Chonnam National University Hospital from 2000 to 2005. And then it was examined that relationship of anomalies of the primary dentition and their successors. Among them 11 children(6 boys, 5 girls) had double teeth or missing teeth. And prevalence of the double teeth was 1.6% and missing teeth was 3.1%. One subject had double teeth in in the mandible and missing teeth in the maxilla. Of the 11 cases of dental anomalies in primary dentition, 7 cases had congenital missing tooth in their successors. This study suggests that the dental anomalies in the primary dentition induced high prevalence of the congenital missing of permanent successors in the permanent dentition.

• Journal of Technologic Dentistry
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• v.15 no.1
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• pp.89-94
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• 1993

The tooth size and shape of the permanent incisor teeth have been studied and analyzed about the mean size, S.D, S.E, etcs and percentage from stone model of 100 Korean male and 74 Korean female. The results were as follows. 1. The crown length of permanent incisor teeth were longer in males than in females statistical differences of males and female were not found. 2. the mesio-distal diameters of permanent incisor teeth were larger in males than in females and statistical differences of males and females were found in mandibular lateral incisor and the bigest were max. central incisor, 2nd max. lateral incisor, 3rd man. lateral incisor and the smallest were man. central incisor. 3. The square form in max. central incisor was the greatest percentage and the tapering form in max. lateral incisor and man, incisor was the greatest percentage but tapering form and ovoid form and other shape were found in max. lateral at the same ratio. 4. Concerning the labial developmental groove "midium" was the greatest percentage in the max. central incisor and "low" was the greatest percentage in the man incisor. Concerning the incisal line, straight line was the greatest percentage in the max, incisor and man, incisor and concerning the lingual tubercle "none" was the greatest percentage in the max. incisor. 5. In comparison between left side and right side of incisor, the ratio of same shape ware 22.4%-36.2% but similar or dissimilar cases were more frequently found.