• Imaging Science in Dentistry
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• 제51권4호
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• pp.373-382
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• 2021

Purpose: Cone-beam computed tomography (CBCT) reconstructions were analysed to elucidate factors affecting the anatomical relationship between tooth roots and the mandibular canal(MC). Materials and Methods: Images of 300 volumetric tomography scans of patients aged between 20 and 79 years old (167 women and 133 men) were analysed. The mean distances between 2,053 dental root apices and the internal border of the MC were obtained by measuring the horizontal and vertical distances on coronal CBCT images. The actual distance was then calculated mathematically with the Pythagorean formula. The statistical significance of differences between men and women was assessed using the Mann-Whitney test. Correlations with patient age were evaluated with the Spearman rank correlation coefficient. Results: The mean distances ranged from 2.17 mm, for single right third molar roots in women, to 8.02 mm for single left third molar mesiolingual roots in men. The mean distances measured for the mandibular right second molar mesial roots and the right second premolar roots were larger in men than in women. Age showed a significant positive correlation with the measured distances for mesial and distal roots of the first and second molar on both sides and the right third molar, mesiolingual roots of the left third molar, and single roots of the right third molar. Conclusion: The root-to-mandibular canal distance depended on age and the type of tooth. In 2 root types, this distance was impacted by sex.

• 치위생과학회지
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• 제7권4호
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• pp.275-279
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• 2007

본 연구는 하악 제3대구치의 맹출 양상이 치관주위염의 발생에 미치는 영향을 조사하고자 양산시에 소재한 N치과병원에 하악 제3대구치 발거를 주소로 내원한 환자 200명을 대상으로 조사연구를 실시하였다. 하악 제3대구치의 좌 우측 분포도, 경사도, 매복정도, 하악지 전연에서의 위치, 하악 제2대구치와 제3대구치 사이의 거리는 $X^2$-test, 치관주위염 유 무와 제 변수와의 상관성은 Pearson 상관관계를 실시하여 다음과 같은 결론을 얻었다. 1. 하악 제3대구치에 대한 치관주위염의 발생은 연령과 상관관계가 있는 것으로 나타났다. 2. 하악 제3대구치의 경사도에 있어서 치관주위염이 가장 호발된 군은 근심경사군이었다. 3. 하악 제3대구치의 매복정도와 치관주위염의 발생은 Level a, Level c, Level b순으로 나타났다. 4. 하악 제3대구치의 하악지 전연에서의 위치는 Class II, I, III의 순으로 치관주위염이 호발하였다. 5. 하악 제2대구치의 원심 백악법랑경계에서 하악 제3대구치의 근심 백악법랑경계까지의 거리가 좁을수록 치관주위염이 호발하였다.

• 대한소아치과학회지
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• 제49권1호
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• pp.35-44
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• 2022

이 연구의 목적은 하악 좌측 제3대구치의 치아 성숙도에 대한 한국인의 참고 자료를 제공하고, 하악 좌측 제3대구치의 석회화 단계와 연대기적 연령 사이의 상관관계를 분석 및 치아 발육 단계를 이용하여 연령을 예측할 수 있을지 알아보는 것이다. 연세대학교 치과대학병원에 내원한 만 7 - 23세 사이의 건강한 환자 1653명의 파노라마 방사선 사진을 이용하여 보완된 Demirjian의 방법으로 하악 좌측 제3대구치의 발육 단계를 평가했다. 제3대구치의 석회화는 평균 9세에 시작하였으며 치관과 치근의 형성은 각각 평균 14세, 21세에 완성되었다. 치관의 형성과 치근 길이가 완성되는 발육 단계에서 남성이 여성보다 다소 빨랐으며, 그 차이는 통계적인 유의성을 보였다. 그 외의 발육 단계에서는 남성과 여성 사이의 유의미한 차이는 없었다. 하악 좌측 제3대구치과 연령은 양의 상관관계를 나타냈으며, 제3대구치의 발육 단계를 이용하여 연령을 예측할 수 있었다. 파노라마 방사선 사진을 이용한 하악 좌측 제3대구치의 치아 성숙도 평가 방법을 통하여 제3대구치의 발육 시기를 분석할 수 있었고, 하악 좌측 제3대구치가 연령을 예측하는 수단으로 활용될 수 있음을 알 수 있었다.

• 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.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.40.1-40.7
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• 2019

Background: Through the analysis of clinical data, we attempted to investigate the etiology and determine the risk of severe iatrogenic lingual nerve injuries in the removal of the mandibular third molar. Methods: A retrospective chart review was performed for patients who had undergone microsurgical repair of lingual nerve injuries. The following data were collected and analyzed: patient sex, age, nerve injury side, type of impaction (Winter's classification, Pell and Gregory's classification). Ratios for the respective lingual nerve injury group data were compared with the ratios of the respective data for the control group, which consisted of data collected from the literature. The data for the control group included previous patients that encountered various complications during the removal of the mandibular third molar. Results: The lingual nerve injury group consisted of 24 males and 58 females. The rate of female patients with iatrogenic lingual nerve injuries was significantly higher than the control groups. Ages ranged from 15 to 67 years, with a mean age of 36.5 years old. Lingual nerve injury was significantly higher in the patient versus the control groups in age. The lingual nerve injury was on the right side in 46 and on the left side in 36 patients. There was no significant difference for the injury side. The distoangular and horizontal ratios were the highest in our lingual nerve injury group. The distoangular impaction rate in our lingual nerve injury group was significantly higher than the rate for the control groups. Conclusion: Distoangular impaction of the mandibular third molar in female patients in their 30s, 40s, and 50s may be a higher risk factor of severe lingual nerve injury in the removal of mandibular third molars.

• 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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• 제39권4호
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• pp.404-411
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• 2012

치아의 매복은 맹출로 내의 물리적 장애물이나 치아의 비정상적 위치에 의해 발생한 치아 맹출의 정지로, 하악 제2대구치의 매복은 비교적 드물다. 매복된 하악 제2대구치는 우식, 치주염, 제1대구치 치근흡수 등을 유발하므로 조기 진단과 치료가 요구된다. 첫 번째 증례는 10세 남자 환자로 하악 양측 제2대구치의 매복을 구리선을 이용하여 치료하였다. 두 번째 증례는 12세 여자 환자로 구강검진 도중 하악 좌측 제2대구치의 매복이 발견되어 Humphrey 장치를 이용하여 치료하였다. 세 번째 증례는 17세 여자 환자로 하악 우측 소구치부에 식립한 미니 임플란트를 고정원으로 하는 uprighting spring을 이용하여 하악 우측 제2대구치의 매복을 치료하였다. 네 번째 증례는 18세 남자 환자로 매복된 하악 좌측 제2대구치에 부착한 교정용 버튼과 하악지에 식립한 미니 임플란트를 elastic thread로 연결하여 치료하였다.

• 치과방사선
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• 제22권2호
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• pp.185-193
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• 1992

경북대학병원 치과에 내원한 8세에서 27세까지의 환자 6,531명의 파노라마 X선사진에서 제3 대구치를 제외한 선천성 결손치, 제3대구치의 선천성 결손, 과잉치의 발생율, 성별분포, 호발 부위 및 수에 따른 분포를 조사하여 다음의 결과를 얻었다. 1. 제3대구치를 제외한 선천성 결손치의 발생율은 10.8%였으며, 남성이 44.6%, 여성이 55.4%였다. 하악 제2소구치가 23.2 %로 가장 많았으며, 상악 측절치 18.4%, 하악 측절치 18.3%, 상악 제2소구치 15.4%의 순으로 나타났다. 결손치의 수는 1개 인 경우가 48%로 가장 많았으며, 2개인 경우가 35.4%, 3개인 경우가 6.6%로 나타났다. 2. 제3대구치 선천성 결손의 발생율은 39.7%였으며, 남성이 48.6%, 여성이 51.4%였고, 상악 60.3%, 하악이 39.7%였다. 결손치의 수는 1개인 경우가 28.7%, 2개인 경우가 37.2%, 3개인 경우가 12.5%, 4개인 경우가 21.6%로 나타났다. 3. 과잉치의 발생율은 4.2%였으며, 남성이 65.7%, 여성이 34.3%였다. 상악 중절치부가 64.8%로 가장 많았으며, 상악 측절치부 13.2%, 상악 제3대구치 후방부 8.7%의 순으로 나타났다. 과잉치의 수는 1개인 경우가 79.9%로 가장 많았고, 2개인 경우가 18.9%, 3개인 경우가 1.2%로 나타났다.

• Imaging Science in Dentistry
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• 제46권1호
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• pp.1-7
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• 2016

Purpose: This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. Materials and Methods: The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Results: Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, $P{\leq}0.01$). 50% of age estimates in the second part of the study fell within a range of error of ${\pm}1year$, while 75% fell within a range of error of ${\pm}2years$. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. Conclusion: The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.29.1-29.5
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• 2017

Background: The surgical extraction of the third molar is the most frequently encountered procedure in oral and maxillofacial surgery and is related with a variety of complications. This study examined the efficacy of intentional partial odontectomy (IPO) in the third molars which have no periapical lesions and are located near important anatomical structures such as inferior alveolar nerve. Methods: Seven patients (four males, three females, $39.1{\pm}11.6years$), who received IPO to reduce the risk of inferior alveolar nerve injury (IANI), were followed long-term. The treated teeth were horizontally impacted third molars in the mandibular left (n = 5) or mandibular right (n = 4) areas and were all ankylosed with the surrounding alveolar bone. During the IPO, the bone around the crown was removed to expose the crown, and then the tooth was resected at cement-enamel junction (CEJ). Any secondary trauma to the healthy root was minimized and remained intact after primary suture. Results: The mean follow-up time was $63.2{\pm}29.8months$, and all sites showed good bone healing after the crown removal. Also, sensory abnormality was not found in any patients after IPO. In one patient, the bone fragments erupted 4 months after IPO. In other patient, an implant placed on second molar site adjacent to the third molar that received IPO was explanted about 2 years after the patient's persistent discomfort. Conclusions: In case where high risk of IANI exists, IPO may be chosen alternatively to surgical extraction to reduce the risk of nerve damage.