• The Journal of the Petrological Society of Korea
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• v.16 no.4
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• pp.217-232
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• 2007

The Puu Oo eruption in Hawaii since 1983 is one of the largest eruptions on Hawaii's volcanic history with prominent compositional variation ($5.6{\sim}10.1wt.%$ in MgO content). Although intense researches of Hawaiian eruption have been conducted for recent years, there is no up-to-date study on Puu Oo lavas that is erupting hot lavas today. in oder to obtain basic information on the geological characteristics of the eruption including any noticeable change in its petrological trend and magma dynamics, we applied several geological approaches such as field survey, systematic sampling, petrography, mineralogy, and geochemistry. Clinopyroxene and Plagioclase phenocrysts are rarely observed on the thin section, however Olivine crysts are much more obvious in the study area. It indicates that Puu Oo is early stage of magma differentiation. Variation diagram of whole rock composition shows that the elements such as $TiO_2,\;Al_2O_3,\;SiO_2$ and $Na_2O$ decrease with increasing MgO. In the trace element Sr, Y Zr and V versus $K_2O$, P18, P19 samples are plotted in primitive area. Variations of the Ni contents during $2003{\sim}2006$ may suggest a sudden change in magma composition probably caused by new magma injection.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.7 no.1
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• pp.25-28
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• 2011

Autism is a developmental, neuropsychiatric disorder that begins in early childhood. A patient with autism seen in the dental office frequently may have many complications. Therefore, it may be needed to consider modified or alternative therapy for dental care of autistic patients. This is the case of a 16-year old boy who have autism. He came to the department of the pediatric dentistry, Yonsei University Dental Hospital, for evaluation and treatment of dentigerous cyst associated with impacted teeth(#33,34,35). Under daily hospitalization and general anesthesia, the cyst was enucleated with surgical extraction of #34 and autotransplantation of #33,35. And during the periodic dental followup, apexification of #33,35 was performed for periapical lesion and root maturity. At 2 year 6 months follow- up, now, bony healing was completed and there are some complications like external resorption of #33 and space loss of #34 area. Generally, the marsupialization has been widely recommended for treatment of dentigerous cyst. However, in this case, there is a little possibility of spontaneous eruption after marsupialization considering of patient's age, location and angulation of the impacted tooth, root maturity. And there is necessity to choose the treatment that has low recurrence risk and needs short-term follow-up for autism. Above all, poor oral hygiene and lack of cooperation for decompression treatment is a matter of primary consideration. Consequently, enucleation of the cyst was chosen for the final treatment plan in this case. It is important to consider the conditions that affect the eruption of a dentigerous cyst-associated tooth to predict the successful eruption and special health care needs of the patient when the treatment plan is settled.

• 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 the korean academy of Pediatric Dentistry
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• v.39 no.4
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• pp.404-411
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• 2012

Tooth impaction is defined as a failure of tooth eruption resulting from the physical obstacles in the eruption path or the abnormal position of the tooth germ. Impaction of mandibular second molar is relatively rare, and it may incite pathologic conditions such as dental caries, periodontitis, or root resorption of adjacent first molar. Thus, early diagnosis and treatment is recommended. In the first case, a 10-year-old male patient, was treated by brass wire to separate the bilaterally impacted mandibular second molars. In the second case, a 12-year-old female patient, was treated with Humphrey appliance for impacted mandibular left second molar, which was detected during a periodical dental examination. In the third case, a 17-year-old female patient with impacted mandibular right second molar, was treated by uprighting spring with mini-implant anchorage around premolar area. In the last case, an 18-year-old male patient, was treated with mini-implant placed on the ramus of mandible connected to the orthodontic buttons bonded on impacted mandibular left second molar by elastic thread.

• The Journal of the Petrological Society of Korea
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• v.26 no.3
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• pp.221-234
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• 2017

The Baengnokdam, the summit crater of Mt. Halla, is one of the representative geosites of World Natural Heritage and Global Geopark in Jeju Island. The crater is marked by two distinctive volcanic lithofacies that comprise: 1) a trachytic lava dome to the west of the crater and 2) trachybasaltic lava flow units covering the gentle eastern slope of the mountain. This study focuses on understanding the formative process of this peculiar volcanic lithofacies association at the summit of Mt. Halla through field observation and optically stimulated luminescence (OSL) dating of the sediments underlying the craterforming volcanics. The trachyte dome to the west of the crater is subdivided into 3 facies units that include: 1) the trachyte breccias originating from initial dome collapse, 2) the trachyte lava-flow unit and 3) the domal main body. On the other side, the trachybasalt is subdivided into 2 facies units that include: 1) the spatter and scoria deposit from the early explosive eruption and 2) lava-flow unit from the later effusion eruption. Quartz OSL dating on the sediments underlying the trachyte breccias and the trachybasaltic lava-flow unit reveals ages of ca. 37 ka and ca. 21 ka, respectively. The results point toward that the Baengnokdam summit crater was formed by eruption of trachybasaltic magma at about 19~21 ka after the trachyte dome formed later than 37 ka.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.1
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• pp.41-47
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• 2013

Maxillary canines are the most commonly impacted or ectopically erupted teeth. If we find the abnormality of maxillary canines early, we can manage it reasonably and systematically. If we cannot see the spontaneous normalization at the periodic recall, primary canine extraction will be the next treatment choice. However, if the primary canine is extracted too early, the extraction socket will be filled with hard bone and then the eruption pathway can be locked. So it is more beneficial to extract the primary canine at the period about 6 months before the normal canine eruption time. The next treatment plan can be surgical and orthodontic approaches before the root apical closure of the impacted canine. Sometimes, surgical extraction and further prosthetic procedure can be needed for a severely malposed impacted canine or badly resorpted incisor. This is the case of the idiopathic mesial movement of impacted maxillary canines.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.1
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• pp.64-71
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• 2014

Mesiodens is defined as a supernumerary tooth in the premaxillary region. It can cause several clinical manifestations in normal eruption and position of adjacent teeth, such as displacement and impaction. Although the mesiodens accompanied by a clinical complication is indicated for removal, the optimal time of mesiodens removal is still controversial. Some authors suggest immediate intervention defining the removal of mesiodens as soon as possible after the first detection. On the other hand, others recommend delayed intervention which denotes the removal of mesiodens after complete root development of adjacent teeth. This case report is presented with three cases of spontaneous correction and proper alignment of rotated maxillary central incisors by extraction of mesiodens when the crowns of rotated incisors were completely formed while the roots of them were at an early developmental stage.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.345-350
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• 2008

In children with Class III malocclusion, it is important to identify whether the etiology is functional, dental, skeletal. FR-III developed by Rolf Frankel in 1970, has been used during deciduous, mixed, and early permanent dentition to correct class III malocclusion characterized by maxillary skeletal retrusion. According Frankel, the vestibular shields and upper labial pads act to counteract the forces of the surrounding musculature that restrict forward maxillary development and cause a retrusion in maxillary tooth position. This can achieve favorable developments with the basal bone, teeth and alveolar bone. We report FR-III that can be applicated in cases of early mixed dentition with mild maxillary deficiency and deepbite before the eruption of permanent maxillary incisor.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.264-272
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• 2007

The purpose of study was to improve the oral hygiene methods for early childhood. The author investigated the oral hygiene materials for early childhood and the oral hygiene methods used by 672 caregivers in Iksan city. The oral hygiene materials were oral tissue, finger brush, toothbrush sets according to the growth stages, electric toothbrush, child toothbrush, toothpaste sets according to the growth stages including eatable toothpaste, and child toothpaste, The rate of caregivers who used each materials was 62.5% for oral tissue, 70.9% for finger brush, 55.9% for toothbrush sets, and 87.4% for eatable tooth-paste. 79.0% of caregivers began toothbrushing from first eruption and about 1 year of age. The rate of swallowing toothpaste was 22% before 48 months, 9% from 48 to 59 months, and 3% after 60 months. The rate of children brushed by caregivers was 52% before 48 months, 42% from 48 to 59 months, and 26% after 60 months. The basic method of oral hygiene management for early childhood is to remove the dental plaque by toothbrushing, and the toothpaste may be used. Suffocation, accidental swallowing, and injury to the throat must be avoided. Generally, the fluoride toothpaste is not recommended before 3 years of age. The least amount of fluoride toothpaste should be used and caregivers should supervise children to prevent the swallowing of toothpaste.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.117-123
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• 2010

Tooth eruption is the movement of the tooth from the developing place in the alveolar bone to the functional position in the oral cavity. The permanent incisors originate from the dental lamina on the lingual side of preceding deciduous tooth and erupt to the level of the occlusion through the well developed gubernacular cord. Ectopic eruption is a developmental disturbance in the eruption pattern of the permanent dentition. Most of the ectopically erupted lower incisor has been found in lingual side. The ectopically erupted tooth could be repositioned by orthodontic force in the early mixed dentition, which could help preventing the problems of loss of space and the lingual tilting of the lower anterior teeth. An eight-year-old girl visited the department of pediatric dentistry, Yonsei Dental University Hospital, for the evaluation and the treatment of the lower right lateral incisor, which was horizontally erupted in the lingual side, parallel to the mouth floor. Her tongue was placed on the labial side of that tooth. There was no previous dental history of dental caries or trauma on the pre-occupied primary incisor. Clinical and radiographic examinations including the computed tomography(CT), showed no evidence of dilacerations on root. Therefore, we decided to start active orthodontic traction of the lower right lateral incisor. We designed the fixed type of buccal arch wire and the lip bumper with hook for the traction. Button was attached to the lingual side of the ectopically positioned tooth. Elastic was used between the appliance and the button on that tooth. After the tooth become upright over the tongue level, appliance was change to the removable type and periodic check-up with occlusal guidance was followed to monitor the position of the tooth. In this case using the fixed appliance with modified form of lip bumper and hook embedded in acrylic part instead of extraction was very efficient up-righting the ectopically erupted tooth toward the occlusal plane.