• 치과방사선
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• 제10권1호
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• pp.41-46
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• 1980

The mandibular canal must be considered carefully during the surgical treatment, especially surgical extraction of the impacted tooth and intraosseous implant, because it contains the important inferior alveolar nerve and vessels. The author investigated the curvature of the mandibular canal and its relation to the mandibular molars and positional realtion between the mental foramen and the mandibular premelors in orthopantomogram. The materials consisted of 441 orthopantomograms divided four groups; Group Ⅰ consisted of 56 males and 44 females from 1 to 6 years of age, Group Ⅱ consisted of 58 males and 45 females from 7 to 12 years of age, Group Ⅲ consisted of 65 males and 33 females from 13 to 18 years of age, Group Ⅳ consisted of 86 males and 54 females over 19 years of age. The results were as followings; 1. The curvature of mandibular canal was 144.50° in Group Ⅰ, 144. 29° in Group Ⅱ, 148.11° in Group Ⅲ, 147.33° in Group Ⅳ. 2. The curvature of mandibular canal was located most frequently on the area between mandibular 1st molar and mandibular 2nd molar in Group Ⅰ (42%) and on the mandibular 2nd molar area in Group Ⅱ (54%), Group Ⅲ (59%), Group Ⅳ (53%). 3. The position of mental foramen was most frequently below the mandibular 1st premolar in Group Ⅰ (58%), between the mandibular 1st premolar and the 2nd premolar in Group Ⅱ (62%), Group Ⅲ (47%), and below the mandibular 2nd premolar in Group Ⅳ (58%).

• Imaging Science in Dentistry
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• 제39권4호
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• pp.209-212
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• 2009

Bifid mandibular canal can be an anatomic variation. This condition can lead to complication when performing mandibular anesthesia or during extraction of lower third molar, placement of implants and surgery in the mandible. Four patients underwent preoperative imaging for extraction of third molars using CBCT (CB Mercuray, Hitachi, Japan). The axial images were processed with CBworks program 2.1 (CyberMed Inc., Seoul, Korea). The branches for supplying the lower third molar were identified mainly on cross-sectional and panoramic images of CBCT. Since the location and configuration of mandibular canal variations are important in any mandibular surgical procedures, we report 4 cases of bifid mandibular canal with panoramic and the CBCT images.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제37권
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• pp.30.1-30.7
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• 2015

Background: The inferior alveolar nerve (IAN) may be injured during extraction of the mandibular third molar, causing severe postoperative complications. Many methods have been described for evaluating the relative position between the mandibular third molar and the inferior alveolar canal (IAC) on panoramic radiography and computed tomography, but conventional radiography provides limited information on the proximity of these two structures. The present study assessed the benefits of three-dimensional computed tomography (3D-CT) prior to surgical extraction of the mandibular third molar, to prevent IAN damage. Methods: This retrospective study included 4917 extractions in 3555 patients who presented for extraction of the mandibular third molars. The cases were classified into three groups, according to anatomical relationship between the mandibular third molars and the IAC on panoramic radiography and whether 3D-CT was performed. Symptoms of IAN damage were assessed using the touch-recognition test. Data were compared using the chi-square test and Fisher's exact test. Results: Among the 32 cases of IAN damage, 6 cases were included in group I (0.35 %, n = 1735 cases), 23 cases in group II (1.1 %, n = 2063 cases), and 3 cases in group III (0.27 %, n = 1119 cases). The chi-square test showed a significant difference in the incidence of IAN damage between groups I and II. No significant difference was observed between groups I and III using Fisher's exact test. In the 6 cases of IAN damage in group I, the mandibular third molar roots were located lingual relative to the IAC in 3 cases and middle relative to the IAC in 3 cases. The overlap was ${\geq}2mm$ in 3 of 6 cases and 0-2 mm in the remaining 3 cases. The mean distance between the mandibular third molar and IAC was 2.2 mm, the maximum distance 12 mm, and the minimum distance 0.5 mm. Greater than 80 % recovery was observed in 15 of 32 (46.8 %) cases of IAN damage. Conclusions: 3D-CT may be a useful tool for assessing the three-dimensional anatomical relationship and proximity between the mandibular third molar and IAC in order to prevent IAN damage during extraction of mandibular third molars.

• 대한치과교정학회지
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• 제46권3호
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• pp.171-179
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• 2016

Objective: The primary aim of the study was to generate new prediction equations for the estimation of maxillary and mandibular canine and premolar widths based on mandibular incisors and first permanent molar widths. Methods: A total of 2,340 calculations (768 based on the sum of mandibular incisor and first permanent molar widths, and 1,572 based on the maxillary and mandibular canine and premolar widths) were performed, and a digital stereomicroscope was used to derive the the digital models and measurements. Mesiodistal widths of maxillary and mandibular teeth were measured via scanned digital models. Results: There was a strong positive correlation between the estimation of maxillary (r = 0.85994, $r^2=0.7395$) and mandibular (r = 0.8708, $r^2=0.7582$) canine and premolar widths. The intraclass correlation coefficients were statistically significant, and the coefficients were in the strong correlation range, with an average of 0.9. Linear regression analysis was used to establish prediction equations. Prediction equations were developed to estimate maxillary arches based on $Y=15.746+0.602{\times}sum$ of mandibular incisors and mandibular first permanent molar widths (sum of mandibular incisors [SMI] + molars), $Y=18.224+0.540{\times}(SMI+molars)$, and $Y=16.186+0.586{\times}(SMI+molars)$ for both genders, and to estimate mandibular arches the parameters used were $Y=16.391+0.564{\times}(SMI+molars)$, $Y=14.444+0.609{\times}(SMI+molars)$, and $Y=19.915+0.481{\times}(SMI+molars)$. Conclusions: These formulas will be helpful for orthodontic diagnosis and clinical treatment planning during the mixed dentition stage.

• 대한치과교정학회지
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• 제11권2호
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• pp.101-108
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• 1981

This investigation was designed to compare the calcification degree of maxillary second permanent molar to mandibular second permanent molar in skeletal Class III Malocclusion. The material selected for this study consisted in standand lateral cephalogram study model and orthopantomogram of two hundred fifty seven Korean Children, one hundred twenty one boys and one hundred twenty four girls, aged 6 through 12 years, having skeletal Class III Malocclusion. On the basis of findigs of this study, the following results were obtained 1. In the stage of completion of crown, there was no significant difference in calcification degree between maxillary second molar and mandibular second molar of both boys and girls in skeletal Class III Malocclusion. 2. From 8 years of age at the stage of beginning root formation to 12 years of age, the calcification degree of mandibular second molar was more advanced than Maxillary second molar of both boys and girls in skeletal Class III Malocclusion.

• 대한치과의사협회지
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• 제41권5호통권408호
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• pp.359-361
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• 2003

A cases report is presented describing treatment : of a mandibular first molar in which three canals were located, prepared, and obtained in the mesial root. The incidence of middle mesial canals in mandibular molars is reviewed 물 treatment considerations are described.

• Journal of Periodontal and Implant Science
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• 제37권2호
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• pp.165-180
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• 2007

Dental Implants have been proved to be successful prosthetic modality in edentulous patients for 10 years. However, there are few reports on the survival of implant according to location in molar regions. The purpose of this study was to evaluate the $4{\sim}5$ years' cumulative survival rate and the cause of failure of dental implants in different locations for maxillary and mandibular molars. Among the implants placed in molar regions in Gwangju Mir Dental Hospital from Jan. 2001 to Jun. 2002, 473 implants from 166 patients(age range; $26{\sim}75$) were followed and evaluated retrospectively for the causes of failure. We included 417 implants in 126 periodontally compromised patients, 56 implants in 40 periodontal healthy patients, and 205 maxillary and 268 mandibular molar implants. Implant survival rates by various subject factors, surgical factors, fixture factors, and prosthetic factors at each location were compared using Chi-square test and Kaplan-Meier cumulative survival analysis was done for follow-up(FU) periods. The overall failure rate at 5 years was 1O.2%(subject level) and 5.5%(implant level). The overall survival rates of implants during the FU periods were 94.5% with 91.3% in maxillary first molar, 91.1% in maxillary second molar, 99.2% in mandibular first molar and 94,8% in mandibular second molar regions. The survival rates differed significantly between both jaws and among different implant locations(p<0.05), whereas the survival rates of functionally loaded implants were similar in different locations. The survival rates were not different according to gender, age, previous periodontal status, surgery stage, bone graft type, or the prosthetic type. The overall survival rate was low in dental implant of too wide diameter(${\geq}5.75$ mm) and the survival rate was significantly lower for wider implant diameter(p

• 대한치과교정학회지
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• 제25권3호
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• pp.299-310
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• 1995

이 연구의 목적은 교정치료시 제2대구치의 위치변화를 알아보기 위함이다. 이를 위하여 제1대구치까지 banding하여 교정치료를 완료한 성인환자 64명을 Class I 발치군 15명, Class I 비발치군 12명, Class II 13명, Class III 14명으로 4개의 군으로 분류하고 치료전후의 두부방사선 계측사진을 분석하였다. 이 연구로부터 얻어진 결과는 다음과 같다. 1. Class I 발치군에서 하악 제2대구치는 제1대구치보다 적은 정출과 더 많은 원심경사를 보였고, 상악 제2대구치는 제1대구치와 유사한 정출과 근심경사를 보였다. 2. Class I 발치군에서 하악 제2대구치는 제1대구치에 비해 함입되고 유사한 원심경사를 보였으며, 상악 제2대구치는 제1대구치와 비슷하게 정출되었다. 3. Class II군에서 하악 제2대구치는 제1대구치에 비해 적은 정출을 보였고, 상악 제2대구치는 제1대구치보다 많은 정출을 보였다. 4. Class III군에서 하악 제2대구치는 제1대구치와 유사한 정출과 더 많은 원심경사를 보였으며, 상악 제2대구치는 제1대구치에 비해 적은 정출을 보였다. 5. 제2대구치 위치변화에 대한 각 군간의 비교시 FH plane에서 상악 제2대구치 치근 분기점까지 거리 변화는 Class I 발치군과 Class II, Class I 발치군과 Class III군에서 차이를 보였으며, 구개평면과 교합평면에 대한 상악 제2대구치의 각도 변화는 Class I 발치군과 Class III군에서 차이를 보였으며, 하악평면에 하악 제2대구치 치근분기점까지 거리변화는 Class I 발치군과 비발치군, Class I 비발치군과 Class II군, Class I 비발치군과 Class III군에서 차이를 보였으며, 하악 평면과 교합평면에 대한 하악 제2대구치의 각도 변화는 각 군간에 차이를 보이지 않았다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권6호
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• pp.565-569
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• 2006

The purpose of this study was to assess the influence of the presence and impacted state of the mandibular third molars on the incidence of mandibular condyle fracture. A retrospective study was designed for patients presenting to the Department of Oral and Maxillofacial Surgery, Kyungpook National University Hospital and Tae-gu Fatima Hospital for treatment of mandibular fractures from January 2003 to January 2006. The independent variables in this study were the presence, degree of impaction of third molars, and the outcome variables were the incidence of mandibular condyle fractures. Hospital charts and panoramic radiographs were used to determine and classify these variables. The demographic data included age, sex, mechanisms of injuries and number of mandibular condyle fractures. The study sample comprised 136 mandibular condyle fractures in 105 patients. Result of this study demonstrated a statistically significant difference in ipsilateral condyle fractures and mandibular third molar absence(P=0.032) and bilateral condyle fractures without another fracture and mandibular third molar absence(P=0.028).

• 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.