• 대한치과교정학회지
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• 제19권1호
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• pp.45-59
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• 1989

This study was undertaken to analyze the displacement and stress distribution in the mandible according to the pulling directions during mandibular first molar cervical traction after mandibular second molar extraction. The 3-dimensional finite element method(FEM) was used for a mathematical model composed of 594 elements and 1019 nodes. An orthodontic force, 450 gm, was applied to the each mandibular first molar in parallel, and below the occlusal plane by $7^{\circ}\;and\;25^{\circ}$ and meet the midsagittal plane by $40^{\circ}$ toward posterior direction. The results were as follows: 1. Mandibular teeth were displaced in more downward, posterior and lateral direction. Especially high stress was noted in case of parallel pull than in case of below the occlusal plane by $7^{\circ}\;and\;25^{\circ}$. 2. Mandibular first molar was moved bodily. 3. Generally, alveolar bone, mandibular body, ascending ramus and mandibular angle portion were displaced in downward, posterior and lateral direction. But coronoid process was displaced in downward, forward and lateral direction, and anterior and inner middle portion of condyle head and neck were displaced in downward, forward and medial direction, and posterior and outer middle portion of condyle head and neck were displaced in upward, forward and medial direction. 4. Maximum stress was observed at the condyle head and neck portion. With steeper direction of force, condyle head and neck showed more stress than parallel relation to the occlusal plane.

• 대한소아치과학회지
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• 제49권3호
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• pp.340-347
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• 2022

하악 제2소구치 치배의 원심 변위는 해당 치아의 매복 뿐만 아니라 하악 제1대구치의 맹출 경로를 방해하여 추가적인 맹출 지연을 야기할 수 있다. 이 증례 보고는 원심으로 변위된 하악 제2소구치로 인해 하악 제1대구치의 맹출 지연이 나타난 두 증례를 소개하고 있다. 원심으로 변위된 하악 제2소구치 치배의 근심 이동을 위해 선행 유치의 의도적 발거술을 시행할 수 있다. 하지만 제2유구치의 조기 상실 시 바람직하지 않은 하악 제1소구치의 원심 이소맹출이 나타날 수 있다. 하악 제1소구치의 바람직하지 않은 원심 이소맹출을 방지하면서 원심으로 변위된 하악 제2소구치 치배를 근심으로 이동시키기 위해 하악 제2유구치의 편측치아절제술 및 순차적 발거를 수행하였다.

• Archives of Plastic Surgery
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• 제38권2호
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• pp.155-160
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• 2011

Purpose: Fibrillar collagens like type I collagen, are the major constituent of the extracellular matrix and structural protein of bone. Also, it can be a scaffold for osteoblast migration. The purpose of this study is to estimate the effects of absorbable atelo-collagen sponge (Teruplug$^{(R)}$, Terumo biomaterials Co., Tokyo, Japan) insertion in tooth extraction sites on periodontal healing of the second molar, healing of the fractured mandibular bone and new bone formation of third molar socket after the extraction of the impacted third molar with mandibular angle fracture. Methods: In our study of six cases of mandibular angle fractures, all of them underwent the extraction of the third molar tooth & absorbable atelo-collagen sponge insertion in tooth extraction site. Three of them had a intraoral infection & oral opening to fracture site, two of the six had dental caries, and only one had reduction problem due to third molar position. Six consecutive patients with noncomminuted fractures of the mandibular angle were treated by open reduction and internal fixation using one noncompression miniplates and screws placed through a transoral incision. Results: All of the patients have showed good postoperative functions and have not experienced complications requiring second surgical intervention. There was well healing of the mandibular bone and the most new bone formation of third molar socket after the extraction of the impacted third molar with mandibular angle fracture. Conclusion: The results of this study suggest that absorbable atelo-collagen sponge is relatively favorable bone void filler with prevention of tissue collapse, food packing, and enhance periodontal healing. Thus, the use of atelo-collagen sponge and one noncompression miniplate seems to be relatively easy, safe, and effective for the treatment of fractures of the mandibular angle and third molar extraction.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권5호
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• pp.201-206
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• 2014

Purpose: To establish management protocol for mandibular angle fracture, we describe pertinent factors including cause, impacted third molar and recent treatment tendency. Methods: We examined the records of 62 patients who had unilateral mandibular angle fracture. Sixty patients who had open reduction surgery were examined at postoperative weeks 1, 4, 8, 12, and 28. Results: Left mandibular angle fracture is frequent in younger males. Presence of the mandibular third molar can increase fracture risk. Because of attached muscle, favorable fractures occurred primarily in the mandibular angle area. Conclusion: Extracting the mandibular third molar can prevent angle fractures, and open reduction with only one plate adaptation is generally the proper treatment method for mandibular angle fracture.

• 대한치과의사협회지
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• 제50권9호
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• pp.566-573
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• 2012

Purpose : This study evaluated the impact of the presence and aspect of mandibular third molars to the mandible angle fracture or condyle fractures in Korean. Materials and Methods : A retrospective study was designed for patients attending the division of Oral and Maxillofacial Surgery, Kang-dong sacred heart hospital for treatment of mandibular fracture from January 2006 to September 2010. The primary variable was the presence of mandibular third molar and the secondary variable was the aspects of third molar impaction. Mandibular third molars were classified by the impaction depth and the available space as Pell & Gregory system. Outcome variables were the presence of mandibular angle fracture or condyle fracture. Also the source of trauma, age, sex were studied. Hospital charts, radiographs were used for study. Statistic analysis was done with descriptive statistics, the X2-test, linear-by-linear association. P value under 0.05 was considered significant statistically. Results : The number of involved patients was 86. The ratio of male to female patients was about 9:1 for angle fracture and 7:3 for condyle fracture. The most common source of trauma was assault for angle fracture and fall down for condyle fracture. The presence of mandibular third molar increased frequency of angle fracture and decreased condyle fracture with larger impaction depth. But available space of mandibular third molar did not show high association with angle or condyle fractures. Conclusion: Preventive extraction of mandibular third molar is recommended for patients with high risk of angle fracture. Male patients at their third decade or martial artists, police officer could be the case. But it is not recommended for patients with low risk of angle fracture and high risk of condyle fracture relatively. Elder female patients without any symptom on their third molar could be the case.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제44권4호
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• pp.167-173
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• 2018

Objectives: Classification of the degree of postoperative nerve damage according to contact with the mandibular canal and buccal cortical bone has been studied, but there is a lack of research on the difference in postoperative courses according to contact with buccal cortical bone. In this study, we divided patients into groups according to contact between the mandibular canal and the buccal cortical bone, and we compared the position of the mandibular canal in the second and first molar areas. Materials and Methods: Class III patients who visited the Dankook University Dental Hospital were included in this study. The following measurements were made at the second and first molar positions: (1) length between the outer margin of the mandibular canal and the buccal cortical margin (a); (2) mandibular thickness at the same level (b); (3) Buccolingual $ratio=(a)/(b){\times}100$; and (4) length between the inferior margin of the mandibular canal and the inferior cortical margin. Results: The distances from the canal to the buccal bone and from the canal to the inferior bone and mandibular thickness were significantly larger in Group II than in Group I. The buccolingual ratio of the canal was larger in Group II in the second molar region. Conclusion: If mandibular canal is in contact with the buccal cortical bone, the canal will run closer to the buccal bone and the inferior border of the mandible in the second and first molar regions.

• Restorative Dentistry and Endodontics
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• 제49권1호
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• pp.2.1-2.12
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• 2024

Objectives: This study aimed to determine the effects of 1-rooted mandibular second molar (MnSM) teeth on root canal anatomy complexities of the mandibular central incisor (MnCI), mandibular lateral incisor (MnLI), mandibular canine (MnCn), mandibular first premolar (MnFP), mandibular second premolar (MnSP), and mandibular first molar (MnFM) teeth. Materials and Methods: Cone-beam computed tomography images of 600 patients with full lower dentition were examined. Individuals with 1-rooted MnSMs were determined, and the complexity of root canal anatomy of other teeth was compared with individuals without 1-rooted MnSMs (Group-1; subjects with at least one 1-rooted MnSM, Group-2; subjects with more than a single root in both MnSMs). A second canal in MnCIs, MnLIs, MnCns, MnFPs, and MnSPs indicated a complicated root canal. The presence of a third root in MnFMs was recorded as complicated. Results: The prevalence of 1-rooted MnSMs was 12.2%, with the C-shaped root type being the most prevalent (9%). There were fewer complicated root canals in MnCIs (p = 0.02), MnLIs (p < 0.001), and MnFPs (p < 0.001) in Group 1. The other teeth showed no difference between the groups (p > 0.05). According to logistic regression analysis, 1-rooted right MnSMs had a negative effect on having complex canal systems of MnLIs and MnFPs. Left MnSMs were explanatory variables on left MnLIs and both MnFPs. Conclusions: In individuals with single-rooted MnSMs, a less complicated root canal system was observed in all teeth except the MnFMs.

• 대한소아치과학회지
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• 제47권2호
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• pp.219-227
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• 2020

치아 맹출은 치조골을 통해 치낭의 위치로부터 구강 내의 최종적인 교합 위치까지 치아가 이동해가는 복잡한 발육 과정이다. 치아의 맹출 장애는 맹출 일련의 단계 중 어느 단계에서도 일어날 수 있으며, 하악 제2유구치의 일차성 만기잔존과 하악 제1대구치의 수평 매복이 동시에 발생한 증례는 매우 드물다. 이번 연구의 목적은 제2유구치의 일차성 만기잔존이 동반된 하악 제1대구치의 수평매복의 두 증례에 대한 치료를 제시하는 것이다. 일차성 만기잔존으로 맹출 지연된 하악 제2유구치는 발치하였고, 수평매복된 하악 제1대구치는 교정적 견인을 시행하였다. 이후 계승 소구치의 맹출 공간을 위해 공간획득을 도모하였고 계승 소구치의 변위가 개선되었으며 제1대구치는 정상적인 맹출이 유도되었다.

• 한국치위생학회지
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• 제5권1호
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• pp.29-38
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• 2005

In 2001, as a subject of this study, the first grade 165 kids in Yomju elementary school had been guided in pit and fissure sealant, fluoride rinse, group tooth brushing, and Dental health education as a part of oral disease preventive program. From the data, this author has estimated incremental dental health care program in school dental clinic in order to make it more effective and enlarge it. For that purpose, the program has been continued at six month intervals for two years. The retention condition of pit and fissure sealant in first molar and DMF rate had been investigated. The conclusions are as follows: 1. Full and partial retention of pit and fissure sealant was measured as 80.69% in maxillary right first molar, 83.20% in maxillary left first molar, and 86.72% in mandibular right first molar, and 86.28% in mandibular left first molar. 2. Retention of pit and fissure sealant in first molar was measured as 76.55% in maxillary right first molar, 81.03% in maxillary left first molar, 80.65% in mandibular left first molar, and 82.03% in mandibular right first molar. 3. Among Yomju elementary school students, DMF rate was measured as 8.7%, and DMFT index as 1.03. However, in Yangdong elementary school students the former was measured as 13.8% and the latter as 1.76. When the DMF rate difference between Yomju and Yangdong elementary school kids was considered, the oral health condition of the former was much better than that of the latter because the former had received incremental dental health care program for two years and on the other hand, the latter had not. So it is necessary that we should enlarge school dental clinic, improve and keep students' oral health.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제43권2호
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• pp.100-105
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• 2017

Objectives: Localization of the mandibular canal (MC) and measurement of the height and width of the available alveolar bone at the proposed implant site in the posterior segment of the mandible using cone-beam computed tomography (CBCT) in patients with a single missing tooth. Materials and Methods: A cross-sectional study was performed where CBCT scans of the patients with a single missing tooth in the posterior segment of the mandible-premolar, I (1st) molar, and II (2nd) molar were used. The scans were assessed using OnDemand3D software (version 1.0; CyberMed Inc., Seoul, Korea) for localization of the MC asnd remaining alveolar bone both vertically (from the superior position of the MC to the crest of the alveolar ridge) and horizontally (buccolingual, 3 mm below the crest of the alveolar ridge). The findings were statistically analyzed using independent t-test. Results: A total of 120 mandibular sites (40 sites for each of the three missing premolar, I molar, and II molar) from 91 CBCT scans were analyzed. The average heights (from the alveolar crest to the superior margin of the MC) at the premolar, I molar, and II molar areas were $15.19{\pm}2.12mm$, $14.53{\pm}2.34mm$, and $14.21{\pm}2.23mm$, respectively. The average widths, measured 3 mm below the crest of the alveolar ridge, at the premolar, I molar, and II molar areas were $6.22{\pm}1.96mm$, $6.51{\pm}1.75mm$, and $7.60{\pm}2.08mm$, respectively. There was no statistically significant difference between males and females regarding the vertical and horizontal measurements of the alveolar ridges. Conclusion: In the study, the measurements were averaged separately for each of the single missing teeth (premolar, I molar, or II molar), giving more accurate information for dental implant placement.