• The Journal of the Korean dental association
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• v.49 no.4
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• pp.211-218
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• 2011

Purpose: An impacted tooth is defined as a tooth that shows delayed eruption and is expected to erupt incompletely by clinical and radiograph examination despite it reaching its expected time of eruption. The aims of this study were to investigate the clinical and radiological characteristics and treatment duration and method of impacted teeth in Korean patients. Materials and Methods: For this study we used clinical records, study models, panoramic radiographs and intraoral photographs of patients who attended Gachon University Gil Hospital Orthodontic Department between 2005 and 2008. There were 164 patients with a total number of 202 impacted teeth. Results: Male patients shows a little more prevalence than female patients (1.13:1). The under 12 age group had the highest prevalence of tooth impaction, and the over 19 age group showed the least prevalence of tooth impaction. The ratio of tooth impaction between the left to right ratio was 1.73:1 and maxilla and mandible was 1.84:1. The impacted teeth were most commonly positioned buccally (76 cases, 41.5%). Full nap closure technique (108 cases, 81.2%)was most frequently used for attachment of surgical traction hooks. Maxillary canine impaction was most commonly encountered both in male and female patients. The mean treatment period was 12.2 months and the success rate of treatment was 90.3%. The canine tooth shows the longest treatment time and highest failure rate. The ankylosis was the major cause of failure. Conclusion: Impacted teeth most commonly show in left side maxilla in the under 12 age group. And it is most commonly positioned buccally. The mean treatment period was 12.2 months, and the success rate of treatment was 90.3%.

• The Journal of the Korean dental association
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• v.22 no.12 s.187
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• pp.1067-1073
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• 1984

In the treatment of functional orthodontic problems, timing is not an issue. All orthodontists start as soon as the condition is recognized. However, there is an active dialogue concerning treatment timing for structure problems. The major points in contention center around the operator's ability is to control the growth of the facial bones and to maintain post-treatment tooth position through the maturation period (especially when this position was gained by techniques involving arch expansion or distal driving of posterior segments). Factors taken into account to determine the best time of orthodontic treatment include diagnosis, interception, growth rate, patient cooperation, eruptive state and treatment period. With those exceptions of all functional problems, mild dental discrepancies and skeletal deficiencies with a predictably excellent growth potential (early treatment), the period immediately following the eruption of the permanent second molars is the period during which most orthodontic treatment should be initiated. At this time the full volume of tooth substances is present, the individual growth pattern in well established, there are sufficient teeth to receive nearly any type of appliances and the patient can easily tolerate the wearing of appliances.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.515-519
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• 2003

Supernumerary teeth are teeth added to the normal complement of teeth. They are most often found in the maxillary anterior region. Most supernumerary teeth in the maxillary anterior region have complications, such as impaction or malposition of permanent teeth, formation of diastema, cysts, and eruption into the nasal cavity or into the oral cavity. These complications have influence on deciding the treatment and its prognosis is depends on how these complications are treated. In clinical studies, it has been found that the removal of supernumerary teeth before the age of 5 years resulted in significant fewer eruption problems of the permanent tooth compared to removal at 7 years of age or later. However, such an early removal may leads to serious consequences of tooth development and behavioral management of patients. Therefore clinicians must consider complications of supernumerary tooth when deciding the time of removal. These cases report five-type of complication associated with supernumerary tooth such as diastema, delayed eruption, external root resorption, migration into nasal cavity and cyst formation.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.777-786
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• 2014

Mt. Ontake is the second highest volcano in Japan. On 02:52 Universal Time Coordinated(UTC), 27th September 2014, Ontake volcano began on the large eruption without notice. Due to the recent eruption, 55 people were killed and around 70 people injured. Therefore, This paper performed numerical experiment to analyse damage effect of volcanic ash corresponding to Ontake volcano erupt. The forecast is based on the outputs of the HYSPLIT Model for volcanic ash. This model, which is based on the UM numerical weather prediction data. Also, a quantitative analysis of the ash dispersion area, it has been detected using satellite images from optical Communication, Ocean and Meterological Satellite-Geostationary Ocean Color Imager (COMS-GOCI) images. Then, the GOCI detected area and simulated ash dispersion area were compared and verified. As the result, the similarity showed the satisfactory result between the detected and simulated area. The concordance ratio between the numerical simulation results and the GOCI images was 38.72 % and 13.57 %, Also, the concordance ratio between the JMA results and the GOCI images was 9.05 % and 11.81 %. When the volcano eruptions, volcanic ash range of damages are wide more than other volcanic materials. Therefore, predicting ash dispersion studies are one of main way to reduce damages.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.101-108
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• 2005

Children are in mixed dentition during 6 years after 3 years old. this time is very important for sound permanent dentition. There are many factors of influence to tooth eruption stage ; adjacent teeth, tooth resorption, early loss or retention of deciduous tooth, local lesion, lip and tongue, masticatory muscles, ect. These factors should be in balance, if not, relation of adjacent teeth is changed, then severe malocclusion is occurred maybe. These cases revealed influences of resin bonded metal splint on occlusal surface of children's molar to mixed dentition. Splints interfere with falling off of deciduous tooth, tooth eruption, normal occlusion formation, and development of mixed dentition and occlusion. Therefore we removed the metal splint from teeth, follow-up checked occlusion and tooth eruption.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.180-184
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• 2001

Cleidocranial Dysplasia(CCD) is an autosomal dominant human bone disease characterized by abnormal clavicles, patent sutures and fontanelles, and dental anomalies. Among dental anomalies, it is characterized that permanent dentition is severly disturbed due to multiple supernumerary teeth and abnormalities of tooth morphology. A eight-year-old female patient diagnosed as cleidocranial dysplasia visited in our hospital. Upon clinical oral exam, retained deciduous teeth, constriction of dental arch, anterior cross bite, and multiple dental caries were observed. In the dental panoramic radiograph, retained deciduous teeth and multiple supernumerary teeth in the maxilla and the mandible were found. In the cephalometric radiograph, open sutures and wormian bones were seen. In the chest P-A view absence of clavicles was observed. The cleidocranial dysplasia patients have eruption problems in permanent dentition both in regions with and without supernumerary teeth. The severely delayed or arrested eruption of permanent teeth has been ascribed to various factors : 1) The presence of multiple supernumerary teeth, 2) malformed roots with lack of cellular cementum, 3) the jaw bone being too dense, and 4) abnormal resorption of bone and primary teeth. Formation and maturation of primary teeth in cleidocranial dysplasia are normal, whereas the permanent dentition has various anomalies. Therefore, dentists should understand the development of dentition in cleidocranial dysplasia, and treat them in proper time.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.303-308
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• 2011

Tooth impaction refers to situations in which the eruption is inhibited by some physical barriers in eruptive path and the tooth remains unerupted beyond the normal time of eruption. The etiology of impacted tooth is controversial, but ankylosis has been suggested probably as a leading role. Impacted primary molars may cause several problems such as space loss, tipping of adjacent teeth, supra-eruption of the antagonists, dislocation of succeeding premolar, cystic change and infection. As one of conventional treatments of impacted primary molars, early tooth extraction or surgical extraction following space regaining when there is space loss has been suggested. However, when they are in normal formation and not ankylosed, orthodontic traction following surgical exposure can be the choice of treatment. In this case, a 3-year-old boy was referred to the department of pediatric dentistry for the unerupted mandibular right second primary molar. After surgical removal of gingiva on the occlusal surface, orthodontic traction was performed. After treatment, we could get normal alignment of primary teeth and the opportunity for normal development of permanent teeth.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.151-164
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• 2011

Mineralogical and petrological characteristics were investigated on matrix of dense gray, vesiculate gray, brown and black pumice in Ulleung Island by using XRD, FT-IR, XRF, SEM and thermal analysis. According to the analysis, most of pumice matrix are amorphous and include very small amount of sanidine and anorthoclase. Since the adsorption moistures, which commonly observed as O-H peak in FT-IR spectrum, are not identified in thermal analysis, it seems reasonable to conclude that content of the adsorption moisture has very low level. Although pumice has a large specific surface area, with long time elapsed after eruption, pumice matrix shows very low degree of hydration alteration due to the low level of water content. In SEM images, most surfaces of pumice show morphological characteristics such as various shapes of vesicle with wrinkled and thin walls resulted from ductile coalescence. Dense gray pumice formed in the initial stage includes small vesicles less than $15{\mu}m$ in size with subangular to angular shapes, free of ovoid vesicle. These characteristics are interpreted to have related to the hydrous environment derived from phreato-plinian eruption. Submicron particles observed as amorphous alumina silicate assemblages in vesicle surface are considered as particles sticked to the matrix surface through rapidly cooling process during ascent of alkali phonolitic magma. It indicates that these particles coexisted partly with crystallized alkali feldspar.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.670-674
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• 2005

Supernumerary tooth develops as a result of abnormal proliferation of the dental lamina during the initiation stage of dental development. It could be a sporadic occurrence or a hereditary transmission. Supernumerary tooth occurs with a frequency of 1 to 3%. Generally, there is a 2:1 preference for boys. It is usually found in the anterior portion of the maxilla and may be associated with complications such as impaction, malposition of permanent teeth, formation of diastema, cysts and eruption into nasal cavity, The position of supernumerary tooth found in the anterior portion of the maxilla is determined by the axis of the tooth. One third of supernumerary tooth in the anterior portion of the maxilla has no possibility of eruption due to its invertedly impacted position. However, as long as the coronal part of the follicle remains intact, migration of supernumerary tooth is possible. The migration may occur into the palate, the premolar region, the sinus or the nasal cavity. Also, growth of vertical dimension of maxilla could make surgical approach difficult as time goes by For this reason, we have found invertedly impacted mesiodens moved to the vault of the palate in the two cases, and extracted supernumerary tooth surgically.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.714-720
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• 2004

This survey was performed as a pilot of comprehensive survey of 18-month old infants which is an important period in pediatric dentistry. Through the oral examination of 154 infants of 18-month age, labored at Pusan National University Hospital and Ilsin Christian Hospital, and direct interview with their first caregivers (mother in most cases), we investigated into the state of their weaning and feeding, between-meal snacks, oral hygiene care, tooth eruption and dental caries and obtained the results as follows : 1. 73% of the infants had not yet weaned, and 82% of which were being milked during or before sleep without oral hygine care. 2. Snacks were taken in order of fruits, biscuits, cheese, bread and candies, and beverages in order of water, fermented milks, milk, sugared juice, fresh fruit juice. 61% of the infants ate snacks irregularly. 3. The toothbrush for infants was the most popular way of oral hygiene care. The mean age of initiation of tooth brushing was 13.8 months and the mean frequency was 1.6 times a day. 4. The incisors in all infants, the 1st molars in 86%, and canines in 66% were erupted. The average number of erupted teeth was 14.1. 5. The caries prevalence rate was 27.3% and 73% of total caries was observed in maxillary deciduous incisors. dmft index was 0.97. Through these results, it was concluded that a systematic education about weaning time, mode of snacking and the way of oral hygine care is required for the parents.