• 대한기계학회논문집A
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• 제24권7호
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• pp.1795-1800
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• 2000

One of the principal sources of vibration and noise in permanent magnetic machines is cogging torque, which is induced by interaction between the rotor poles and the stator teeth. For its analysis, using finite element analysis is very time consuming and the calculation of performance factors is extremely sensitive to the discretization. Especially, Maxwell stress tensor method is sensitive to the location of integral path. In this paper, a cogging permeance fuction is defined and replaced by the straight line. And it is assumed that the flux density acting on the stator's tooth side is the euqal to the flux density of the slot area. Using this definition and assumption, analytical calculation of cogging torque is presented and validated. And several reduction method is introduced.

• Imaging Science in Dentistry
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• 제33권1호
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• pp.59-62
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• 2003

Ameloblastic fibro-odontoma is an extremely rare odontogenic tumor composed of proliferating ectodermal and mesenchymal components of odontogenic tissue, containing hard tooth structure. It occurs predominantly in children and young adults. The mandibular molar-ramus area is the most frequently observed location, presenting radiographically as a well-circumscribed and radiolucent-radiopaque tumor. A case involving a 24-year-old woman presenting with a large ameloblastic fibro-odontoma of the posterior mandible is reported. This case is of radiologic interest because two distinct calcification patterns were observed.

• 치과방사선
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• 제15권1호
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• pp.21-26
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• 1985

The author observed 97 cases ameloblastoma diagnosed in Department of Oral Radiology in Seoul National University and analyzed patient's age, sex, location, relation with adjacent anatomic structures, and radiographic forms. The obtained results are as follows: 1. The average age of patients was 28.7 years. The mean age of male was 28.5 years, and female's 30.0 years. Third decades revealed highest rate. 2. The occurrence of ameloblastoma is approximately evenly distributed in both sexes, male 46 cases (47.2%), female 51 cases (52.6%). 3. Ninty-five (98.0%) cases occurred in the mandible. The mandibular molar-ramus region was the most frequent site of the tumor (74 cases, 76.3%). 4. Most of the cases affected adjacent anatomic structures. 24 cases (24.7%) were shown to be definitely associated with an impacted tooth. 5. Radiographic forms are unilocular (29 cases, 29.3%), honeycomb (17 cases, 17.5%), and multilocular (67 cases, 69.1%) radiolucencies.

• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.75-78
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• 2015

Presented here is a case where 8 canals were located in a mandibular first molar. A patient with continuing pain in mandibular left first molar even after completion of biomechanical preparation was referred by a dentist. Following basic laws of the pulp chamber floor anatomy, 8 canals were located in three steps with 4 canals in each root. In both of the roots, 4 separate canals commenced which joined into two canals and exited as two separate foramina. At 6 mon follow-up visit, the tooth was found to be asymptomatic and revealed normal radiographic periapical area. The case stresses on the fact that understanding the laws of pulp chamber anatomy and complying with them while attempting to locate additional canals can prevent missing canals.

• Imaging Science in Dentistry
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• 제50권4호
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• pp.377-384
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• 2020

This report presents 2 cases of sinus fungus ball and describes the characteristic radiographic features of fungus ball in the maxillary sinus. Two female patients, aged 62 and 40 years, sought consultations at a dental hospital for the treatment of dental implants and tooth pain, respectively. Panoramic radiography and small field-of-view(FOV) cone-beam computed tomography (CBCT) did not provide detailed information for the radiographic diagnosis of fungus ball due to the limited images of the maxillary sinus. Additional paranasal sinus computed tomographic images showed the characteristic features of fungus ball, such as heterogeneous opacification and intralesional calcification of the maxillary sinus. The calcified materials of the fungus balls were located in the middle and superior regions of the maxillary sinus. It is necessary to use large-FOV CBCT for the detection of calcified materials in the upper maxillary sinus to confirm the diagnosis of fungus ball.

• Restorative Dentistry and Endodontics
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• 제41권3호
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• pp.182-188
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• 2016

Objectives: The purpose of this study was to evaluate the proximity of the mandibular molar apex to the buccal bone surface in order to provide anatomic information for apical surgery. Materials and Methods: Cone-beam computed tomography (CBCT) images of 127 mandibular first molars and 153 mandibular second molars were analyzed from 160 patients' records. The distance was measured from the buccal bone surface to the root apex and the apical 3.0 mm on the cross-sectional view of CBCT. Results: The second molar apex and apical 3 mm were located significantly deeper relative to the buccal bone surface compared with the first molar (p < 0.01). For the mandibular second molars, the distance from the buccal bone surface to the root apex was significantly shorter in patients over 70 years of age (p < 0.05). Furthermore, this distance was significantly shorter when the first molar was missing compared to nonmissing cases (p < 0.05). For the mandibular first molars, the distance to the distal root apex of one distal-rooted tooth was significantly greater than the distance to the disto-buccal root apex (p < 0.01). In mandibular second molar, the distance to the apex of C-shaped roots was significantly greater than the distance to the mesial root apex of non-C-shaped roots (p < 0.01). Conclusions: For apical surgery in mandibular molars, the distance from the buccal bone surface to the apex and apical 3 mm is significantly affected by the location, patient age, an adjacent missing anterior tooth, and root configuration.

• 대한소아치과학회지
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• 제26권1호
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• pp.157-161
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• 1999

1. Periphelal odontoma는 매우 드문 질환으로 확진을 위해서는 생검이 필수적이다. 2. Peripheral odontoma는 치은의 종창을 동반하며 서서히 성장하는 임상적 특징을 가진다. 3. 골내 치아종과 마찬가지로 peripheral odontoma의 치료로는 완전한 외과적 절제가 추천되고 예후 또한 양호하다.

• Journal of Periodontal and Implant Science
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• 제41권2호
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• pp.92-97
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• 2011

Purpose: The present study was performed to compare the treatment outcomes of non-surgical periodontal treatment according to the distribution of attachment loss of a given patient. Methods: Forty-five patients with moderate to severe periodontitis were divided in two subgroups; Group I patients with teeth manifesting attachment loss of ${\geq}$ 6 mm at one or more sites on the buccal/labial aspect while maintaining an attachment level ${\leq}$ 5 mm at the lingual/palatal aspect, Group II patients with teeth manifesting an attachment level ${\geq}$ 6 mm at more than one site on the lingual/palatal aspect while maintaining an attachment level ${\leq}$ 5 mm at the buccal/labial aspect. The probing pocket depth, probing attachment level, tooth mobility, and chewing discomfort were recorded at baseline and 6 months examinations following non-surgical periodontal therapy. Results: The buccal/ abial surfaces of teeth with moderate to severe periodontitis in Group I patients demonstrated a greater amount of pocket reduction, gain of attachment level, and tooth mobility reduction than the lingual/palatal aspects of teeth examined in Group II patients. Conclusions: Within the limits of the present study, the patients demonstrating attachment loss ${\geq}$ 6 mm at buccal/labial surfaces responded better to the nonsurgical periodontal therapy than those demonstrating comparable attachment loss at lingual/ palatal surfaces.

• 대한소아치과학회지
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• 제34권4호
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• pp.709-717
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• 2007

상악 전치의 매복은 제3대구치, 상악 견치, 상하악 제2소구치에 비해서 드물지만, 정중 과잉치, 외상, 치근만곡 등의 치근형성의 변이가 높은 빈도로 나타나기 때문에 다른 전치부에 비해서는 매복되는 비율이 높고, 보통 약 8세 이후의 초기 혼합치열기의 아동에서 관찰된다. 상악 중절치의 매복으로 인한 인접치아의 이동으로 공간상실과 함께 정중선 변이가 나타날 수 있고 낭종 등이 발생할 수 있으므로, 정확한 위치를 확인하고 적절한 치료 계획을 세우는 것이 중요하다. 치료 방법으로는 외과적 발거, 자발적 맹출의 관찰, 교정적 견인 등이 있으나, 매복치의 병적 변화가 없고, 치근의 발육이 양호하다면 기능과 심미성의 회복을 위해 교정적 견인을 시행한다. 이에 매복된 상악 전치들을 교정적 견인을 통해 정상적인 맹출방향으로 유도하여 양호한 치료결과를 얻었기에 보고하는 바이다.

• Journal of Korean Dental Science
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• 제7권1호
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• pp.31-37
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• 2014

Dentigerous cyst (DC) is an odontogenic cyst associated with the crown of an impacted, embedded, unerupted, or developing tooth. It is the second most common type of odontogenic cysts, accounting for 14% to 24% of all jaw cysts. Although these cysts occur more frequently during the second and third decades of life, they can also be found in children and adolescents in the mixed dentition stage. Treatment of the odontogenic cyst involves enucleation or marsupialization/decompression methods. The latter approach is preferred for larger cysts, and it is especially helpful in adolescent patients in conserving the unerupted permanent successors. The aim of treatment for DC is the complete elimination of pathology and maintenance of dentition with minimal surgical intervention. Recently defined criteria for the selection of treatment modality include the cyst size and location of the cyst, patient age, dentition involved, stage of root development, position of the tooth involved in the jaw, and relationship with the surrounding vital structure. Marsupialization or decompression technique has been advocated by several authors for treating DCs among young patients. In this conservative technique, the creation of an accessory cavity helps relieve intra-cystic pressure and accelerate the healing of cystic lesion. This technique has been successfully performed and is indicated for growing children and adolescents. Here, we report a large cyst lesion in the mandible treated by marsupialization for conservative management. In conclusion, successful reduction in size was achieved, and intraoperative complication could be prevented.