하악 제 3대구치의 치근 만곡도와 매복정도의 관계 분석

임재석(Jae-Suk Rim),권종진(Jong-Jin Kwon),장현석(Hyun-Seok Jang),박영준(Young-Joon Park),전상호(Sang-Ho Jun),현승돈(Seung-Don Hyun) 대한구강악안면외과학회 2002 대한구강악안면외과학회지 Vol.28 No.1

Purpose : We examined the relationships between the root curvatures of the mandibular third molars and their locations on the mandible, so that it might be contributed to elucidate the origin of the formation and development of the Korean mandibular third molar and help many clinicians to treat the mandibular third molars. Materials and Methods : Panoramic radiographs of 237 patients who had been treated at Korea University Ansan Hospital from March, 2000 to April, 2001 and had bilateral mandibular third molars were examined and analyzed. Results : There was no statistically significant difference between men and women (p<0.05). But there were significantly fewer subjects with bilateral curved roots in bilateral third molars regardless of their status (p<0.01) and were statistically significant differences between the groups with bilateral curved roots in the mandibular third molars with same status and with unilateral curved roots in the mandibular third molars with different status and between the groups with unilateral curved roots in the mandibular third molars with same status and with bilateral curved roots in the mandibular third molars with different status(p<0.05). Subjects with bilateral curved roots in the mandibular third molars with bilateral partial impacted status and with bilateral curved roots in the mandibular third molars with bilateral complete eruption status were significantly fewer (p<0.01) and subjects with the mandibular third molars with partial impacted and complete impacted status and with the mandibular third molars with complete erupted and partial impacted status had significantly fewer bilateral curved roots (p<0.05). Conclusions : When we postulate that it is genetic and environmental factors that affect the root formation, it seems that environmental factors have more effects on the formation of the mandibular third molars than on that of the mandibular first and second molars

Correlation of panoramic radiographs and cone beam computed tomography in the assessment of a superimposed relationship between the mandibular canal and impacted third molars

정연화,나경수,조봉혜 대한영상치의학회 2012 Imaging Science in Dentistry Vol.42 No.3

Purpose: This study evaluated the association between cone beam computed tomography (CBCT) and panoramic radiographs in the assessment of a superimposed relationship between the mandibular canal and impacted third molars. Materials and Methods: The study samples consisted of 175 impacted third molars from 131 patients who showed a superimposed relationship between the mandibular canal and third molars on panoramic radiographs and were referred for the examination of the mandibular canal with CBCT. Panoramic images were evaluated for the darkening of the root and the interruption of the mandibular canal wall. CBCT images were used to assess the buccolingual position of the mandibular canal relative to the third molar, the proximity of the roots to the canal, and lingual cortical bone loss. The association of the panoramic and CBCT findings was examined using a Chi-square test and Fisher’s exact test. Results: Panoramic radiographic signs were statistically associated with CBCT findings (P⁄0.01). In cases of darkening roots, lingual cortical bone loss or buccally positioned canals were more frequent. In cases in which the mandibular canal wall was interrupted on panoramic radiographs, contact or lingually positioned canals were more frequent. Conclusion: The results of this study suggest that contact between the mandibular third molar and canal and a lingually positioned canal could be more frequently observed in cases of the interruption of the white line of the mandibular canal and that there could be more lingual cortical loss in cases of darkening roots. Purpose: This study evaluated the association between cone beam computed tomography (CBCT) and panoramic radiographs in the assessment of a superimposed relationship between the mandibular canal and impacted third molars. Materials and Methods: The study samples consisted of 175 impacted third molars from 131 patients who showed a superimposed relationship between the mandibular canal and third molars on panoramic radiographs and were referred for the examination of the mandibular canal with CBCT. Panoramic images were evaluated for the darkening of the root and the interruption of the mandibular canal wall. CBCT images were used to assess the buccolingual position of the mandibular canal relative to the third molar, the proximity of the roots to the canal, and lingual cortical bone loss. The association of the panoramic and CBCT findings was examined using a Chi-square test and Fisher’s exact test. Results: Panoramic radiographic signs were statistically associated with CBCT findings (P⁄0.01). In cases of darkening roots, lingual cortical bone loss or buccally positioned canals were more frequent. In cases in which the mandibular canal wall was interrupted on panoramic radiographs, contact or lingually positioned canals were more frequent. Conclusion: The results of this study suggest that contact between the mandibular third molar and canal and a lingually positioned canal could be more frequently observed in cases of the interruption of the white line of the mandibular canal and that there could be more lingual cortical loss in cases of darkening roots.

젊은 성인에서의 하악 매복 제 3 대구치의 맹출과 위치변화에 대한 방사선학적 평가

김효섭,이재훈 大韓顎顔面成形再建外科學會 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.4

The third molar appears to be the most frequently impacted tooth. In most studies, the frequency of mandibular third molar impaction has been found to be 20-30%, with females showing third molar impaction significantly more often than males. During development, the position of the mandibular third molar changes countinously before reuption or impaction. Unless this movement is disturbed, the mandibular third molar will erupt normally into the functional position. Panoramic tomographs are usually taken for clincal examinaion and treatment planning. To determine the timing of surgical intervention, it would be beneficial to dertermine certain predictive signs about the future eruption from the panormic radiograph while the tooth is still developing. To estmate whether mandibular third molar are likely to erupt after the age of 20 by determining radiographic feature, we took a study on 25 patients (Average age was 20.2±0.7)with 30 impacted mandibular third molars. Panoramic radiograph was taken at age 20 and 25. The results were as follows. 76.9% of the mandibular third molars with initially complete root development fully erupted by the age of 25 years. however, teeth with incomplete root development more often remained unerupted. The mandibular third molar which impacted in only soft tissue or by the occlusal level to the mandibular second molar erupted more often than other impactions. Initially vertical angulated teeth erupted more often than other angulations. There was a statistically significant difference of angulations change between age 20 and age 25(P<0.05). In the retromolar space/MD width of mandibular third molar ratio, there was a statistically significant difference between the erupted group and the impacted group(P<0.01). It was conclued that we could find the predictive radiographic features to estimate future eruption of mandibular third molars from a panoremic tomograph taken at age 20 years.

하악 제3대구치의 위치와 각도가 발치 후 합병증에 미치는 영향

홍선표(Sun-Pyo Hong),임헌준(Hun-Jun Lim),김원기(Won-Ki Kim),김용운(Yong-Woon Kim),오세리(Se-Ri Oh),이 준(Jun Lee),민승기(Seung-Ki Min) 대한구강악안면외과학회 2011 대한구강악안면외과학회지 Vol.37 No.5

Introduction: Mandibular third molar extraction is one of the most common procedures performed in oral and maxillofacial surgery units. Although the overall complication rate is low with most complications being minor, mandibular third molar removal is so common that the population morbidity of complications might be significant 1,2 . Therefore, efforts to limit intraoperative or postoperative complications might have a significant impact in terms of enhancing the patient outcome. The aims of this study were to identify the position and angulation associated complications after mandibular third molar extractions. Materials and Methods: This study surveyed 568 patients who had a mandibular third molar extracted, showed clinical complications and underwent a radiographic measurement of the available space, depth and spatial relationship. Results: The results obtained were as follows: 1. The complications were a dry socket, nerve injury, root rest, infection, bleeding, hamatoma, and adjacent teeth injury. 2. There were no significant differences between the complication and ramus relationship (available space) of the mandibular third molar. 3. There were no significant differences between the complications and depth of the mandibular third molar. 4. There were no significant differences between the complications and spatial relationship of the mandibular third molar. Conclusion: There were no significant differences in the complication rate, ramus relationship, depth and spatial relationship of the mandibular third molar. This suggests that the position and angulation of the mandibular third molar may not have an impact on the complications. The relationship between the position and angulation of the mandibular third molar, and complications deserves a further study using longitudinal data.

Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts

Hang-Gul Kim,Jae-Hoon Lee 대한구강악안면외과학회 2014 대한구강악안면외과학회지 Vol.40 No.6

Objectives: This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods: Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results: When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion: The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage.

하악 제3대구치와 하악 우각부 골절과의 상관관계

유석현,이형주,문지원,손동석,Yu, Seok-Hyun,Lee, Hyung-Ju,Moon, Jee-Won,Sohn, Dong-Seok 대한악안면성형재건외과학회 2011 Maxillofacial Plastic Reconstructive Surgery Vol.33 No.6

Purpose: This study evaluated correlation and risk factors between position of the mandibular third molars and mandibular angle fractures using clinical and radiographic findings. Methods: Medical records and panoramic radiographs of 188 patients with mandibular fractures were retrospectively reviewed. The presence and position of the third molars were assessed for each patient and were related to the occurrence of mandibular angle fractures. Results: The incidence of mandibular angle fracture was found to be greater when a lower third molar was present, particularly at the occlusal plane positioned on the $2^{nd}$ molar occlusal surface (by Archer system) and the third molar is impacted in mandibular ramus (by Pell & Gregory system). Of the 192 sites with a lower third molar, 32 (16%) had an angle fracture. Of the 184 site without lower third molars, 16 (8%) had an angle fracture. Conclusion: This study confirmed an increased risk of angle fractures in the presence of a lower third molar as well as variable risk for angle fracture, depending on positioning of the third molar.

제3대구치와 하악관과의 위치 관계에서 치과용 Cone beam CT의 유용성

추연규,박영인,김진욱,이상한,Chu, Yeon-Gyu,Park, Young-In,Kim, Jin-Wook,Lee, Sang-Han 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.6

We sought to evaluate the relationship between the mandibular canal and impacted mandibular third molars by using dental cone beam computed tomograph(CBCT) for third molar surgery. A total of 111 patients(177 teeth) offered the images through CBCT and panoramic radiography for the extraction of the mandibular third molars. In CBCT, the accurate relationship between the third molar and the mandibular canal were evaluated. In panoramic radiographies, we evaluated the impacted level and superimposition sign of the mandibular third molar with the mandibular canal, and also, the radiopacity of the white line in the canal. Data were statistically analyzed and estimated by $X^2$-test. In CBCT finding, high prevalence of contact between the mandibular canal and roots occured in the deep impacted third molars, narrowing mandibular canals, bending mandibular canals and cases where the radiopacity of white line of canals were "absence" on panoramic images. It showed statistical significance (P<0.05). When evaluating the mandibular canal and the roots through the panoramic radiography for third molar extraction, it could be difficult to diagnosis accurately. Thus, it is required to have an accurate diagnostic approach through CBCT that could evaluated the location between mandibular canal and root.

국군 장병의 매복 하악 제3대구치의 평가 : 후향적 방사선 연구

장영훈 ( Young-hun Jang ) 국군의무사령부 2013 대한군진의학학술지 Vol.44 No.1

Objectives : The mandibular third molar is the most frequently impacted by its expected age of approximately 20. Most Korean soldiers who serve mandatory military duty suffer from mandibular third molar, because they are early twenties. The aim of this study was to study incidence of pattern of impaction of mandibular third molars in the military soldiers, and predict possibility of inferior alveolar nerve injury after tooth extraction. Methods : From April, 2011 to April, 2013, the 220 male soldiers, ranging in age from 20 to 30 years (23.3 years), who visited in the Department of Dentistry, Korea Naval 3rd Fleet and the panoramic radiographies were taken for oral examination, was selected. Radiographically, the angulation, the level of eruption, the ramus classification, and the radiological risk signs of the mandibular third molars to inferior alveolar canal were evaluated. Results : In the panoramic findings, 184 (83.6%) soldiers had one or more impacted mandibular third molars. Mesioangular impaction (39.5%), Level B (53.3%) and Class II (80.4%) were most prevalent. And 53.6% of mandibular third molars showed proximity to the inferior alveolar canal Conculusions : Most soldiers need surgical extraction for mandibular third molars which were complicated impaction. However, clinicians have to extract very carefully because more than half of mandibular third molars showed proximity to the inferior alveolar canal.

파노라마 방사선사진과 cone beam CT에서 하악 제3대구치와 하악관의 관계 평가

정연화,나경수,조봉혜 대한구강악안면방사선학회 2008 Imaging Science in Dentistry Vol.38 No.3

Purpose : The purpose of this study is to evaluate the position of the mandibular canal in relation to the mandibular third molar by cone beam CT in cases showing a close relationship between the third molar and the mandibular canal on the panoramic radiograph. Materials and Methods : The panoramic images and cone beam CT scans of 87 impacted mandibular third molars in 60 patients were evaluated to assess the tooth relationship to the mandibular canal. The clearness of the canal wall and the vertical depth of the lower third molar were evaluated on panoramic radiographs. The lower third molars were assessed using cone beam CT to determine the proximity and position of the canal relative to the roots. Results : In the 66 cases where the canal wall was unclear on the panoramic radiographs, 58 (87.9%) of the third molars had contact between the canal and root; 34 (51.5%) canals were showed an inferior position and 22 (33.3%) showed a linguoinferior position on cone beam CT. Conclusion : Interruption of the canal wall on panoramic radiographs was highly predictive of contact between the mandibular canal and the third molar. Cross sectional CT may be indicated for localization of the mandibular canal in such cases.

콘빔 CT를 이용한 하악 제3대구치부의 부하악관 평가

조봉혜(Bong-Hae Cho),정연화(Yun-Hoa Jung) 대한치과의사협회 2014 대한치과의사협회지 Vol.52 No.12

Purpose: This study was performed to examine distribution of accessory mandibular canal and its characteristics in mandibular third molars. Materials and methods: A total of 251 subjects (166 males and 85 females) having mandibular third molars bilaterally were included in the study. Cone beam computed tomographic images were reviewed for bifid or trifid accessory mandibular canal. The prevalence of accessory mandibular canal was evaluated according to gender, side and its branching type. Proximity and cross sectional position of accessory mandibular canal to mandibular third molar was analyzed. Results: Accessory mandibular canals were found in 66 (26.3%) of 251 patients and 86 (17.1%) of 502 hemi mandibles. Gender and sides showed no statistically significant differences in prevalence. Retromolar canal (46.1%) was the most common branching type. Proximity of accessory canal to mandibular third molars showed mean distance of 2.8 mm from third molar and a statistically significant difference was found among types of accessory canal. Dental canal was the closest to tooth among branching types and closer to tooth than main canal. On cross sectional view, accessory canal was generally located on buccal side of mandibular third molar. Conclusion: Accessory mandibular canal was common and well detected with cone beam computed tomography. Their localization is significant in all anesthetic and surgical procedures involving mandibular third molars.