• The Journal of the Korean dental association
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• v.57 no.11
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• pp.654-663
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• 2019

This case report describes the management of a 30-year-old woman with hopeless mandibular first molars and right maxillary second premolar. The treatment plan included mandibular second and third molar protraction after extraction of mandibular first molars. Mini-implants were placed between roots of first and second premolar. Sliding mechanics with lever arm was used to prevent inclination of molars. A good functional occlusion was achieved in 38 months without clinically significant side effects. Most of the extraction space of mandibular first molar was closed by protraction of second and third molars. The skeletal Class II pattern was improved by counterclockwise rotation of mandible through reduction of wedge effect. Mandibular molar protraction with orthodontic mini-implants in adequate cases would be a great alternative to prosthetic implant and reduce the financial and surgical burden of patients.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.252-260
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• 2013

Purpose: After the introduction of concept of osteointegration, dental implantology have been successful procedure in the dental field. Recently, it has shown successful results when used to restore single tooth missing. Considering the difference in bone quality of the mandible and maxilla, and the increased occlusal force in the posterior region, the success rates in each region may be different. In this study, success rates of single implants placed in the mandibular first and second molar areas were analyzed. Materials and methods: The subjects were patients (284 patients, 308 implants) who had been operated with single implant installation from 2002 to 2009 in seven dental clinics in Daegu city. One hundred sixty eight implants were placed in the mandibular 1st molar and 140 implants were placed in the mandibular 2nd molar. They were analyzed according to implant site, age, sex, length and diameter. Results: The survival rates of single implant of this study were 97.6% in the mandibular 1st molar and 92.9% in the mandibular 2nd molar. In the mandibular 1st molar, 4 implants were failed. In the mandibular, 2nd molar, 10 implants were failed. Conclusion: The restoration of the mandibular 1st molar using single implant was found to be clinically acceptable treatment and showed higher survival rate than mandibular 2nd molar single implant. Single implant in mandibular 2nd molar needs careful consideration of poor bone quality, risk of overloading and anatomical structure of the mandible.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.420-425
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• 2009

Purpose: The aim of this study is to analyze the correlation between incidence of mandibular angle fracture and eruption state of mandibular third molar using clinical and radiographic findings. Materials and Methods: The data were obtained from the clinical and radiographic records of 205 patients who visited the Department of Oral and Maxillofacial Surgery, Chonbuk National University Hospital for treatment of the mandibular fracture. Panoramic radiographies were taken for radiographic examination and the mandibular third molars were classified according to age, gender, position and eruption state. Data were analyzed by a chi-square statistics. Results: In this study, the incidence of mandibular angle fracture had a tendency to be greater when a mandibular third molar was present(p>0.05), but there was not a statistically significant difference. Of the 255 cases with a mandibular third molar, 67 had an angle fractures. Of the 155 cases without a mandibular third molar, 138 had not angle fracture. And the incidence of mandibular angle fracture was high at class BII(by Pell & Gregory system)(p<0.05). Conclusion: Although there was not a statistically significant difference, mandibular third molar was more susceptible to mandibular angle fracture. When the reduction of mandibular angle fracture, it was recommended that mandibular third molar should be extracted especially in case of pericoronitis, periodontitis and other infections.

• Imaging Science in Dentistry
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• v.39 no.2
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• pp.89-92
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• 2009

Purpose: To assess the angle between mandibular canal and occlusal plane at each posterior tooth region and location of mental foramen on the panoramic radiographs. Materials and Methods: This study analysed 46 half-mandibles of panoramic radiographs. Inferior border of mandibular canal was traced. Occlusal plane was drawn from lingual cusp tip of the first premolar to distolingual cusp tip of the second molar. Perpendicular line from occlusal plane was drawn at each tooth region and then tangential lines were drawn from the crossing points at canal. the angle between occlusal plane and tangential line was measured. The location of mental foramen was also studied. According to the location of mental foramen, radiographs were divided into M (mesial) group and D (distal) group on the basis of the second premolar. and then inter-group analysis about mandibular canal angle was done. Results: The angles of mandibular canals were -17.7$^{\circ}$, -9.5$^{\circ}$, 8.2$^{\circ}$, 22.3$^{\circ}$, and 39.2$^{\circ}$at first premolar, second premolar, first molar, second molar, and third molar, respectively. The commonest position of the mental foramen was distal to the second premolar. Inter-group comparison showed statistically significant difference at the second premolar and the first molar(p<0.001). Conclusion: The knowledge of mandibular canal angle and location of mental foramen can help understanding the course of mandibular canal. (Korean J Oral Maxillofac Radiol 2009; 39: 89-92)

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.1
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• pp.63-67
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• 2022

Controversies exist regarding the need for prophylactic extraction of mandibular third molars in patients who plan to undergo orthognathic surgery. An 18-year-old male patient was diagnosed with mandibular prognathism and maxillary retrognathism with mild facial asymmetry. He had a severely damaged mandibular first molar and a horizontally impacted third molar. After extraction of the first molar, the second molar was protracted into the first molar space, and the third molar erupted into the posterior line of occlusion. The orthognathic surgery involved clockwise rotation of the maxillomandibular complex as well as angle shaving and chin border trimming. Patients who are missing or have damaged mandibular molars should be monitored for eruption of third molars to replace the missing posterior tooth regardless of the timing of orthognathic surgery.

• Restorative Dentistry and Endodontics
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• v.41 no.3
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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.

• The korean journal of orthodontics
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• v.42 no.3
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• pp.110-117
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• 2012

Objective: In this study, we measured the cortical bone thickness in the mandibular buccal and lingual areas using computed tomography in order to evaluate the suitability of these areas for application of temporary anchorage devices (TADs) and to suggest a clinical guide for TADs. Methods: The buccal and lingual cortical bone thickness was measured in 15 men and 15 women. Bone thickness was measured 4 mm apical to the interdental cementoenamel junction between the mandibular canine and the 2nd molar using the transaxial slices in computed tomography images. Results: The cortical bone in the mandibular buccal and lingual areas was thicker in men than in women. In men, the mandibular lingual cortical bone was thicker than the buccal cortical bone, except between the 1st and 2nd molars on both sides. In women, the mandibular lingual cortical bone was thicker in all regions when compared to the buccal cortical bone. The mandibular buccal cortical bone thickness increased from the canine to the molars. The mandibular lingual cortical bone was thickest between the 1st and 2nd premolars, followed by the areas between the canine and 1st premolar, between the 2nd premolar and 1st molar, and between the 1st molar and 2nd molar. Conclusions: There is sufficient cortical bone for TAD applications in the mandibular buccal and lingual areas. This provides the basis and guidelines for the clinical use of TADs in the mandibular buccal and lingual areas.

• Imaging Science in Dentistry
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• v.38 no.3
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• pp.163-167
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• 2008

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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.5
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• pp.242-245
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• 2013

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposition without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.6
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• pp.492-498
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• 2009

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.