• 대한치과교정학회:학술대회논문집
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• 2005.11a
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• pp.70.1-70.1
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• 2005

• Imaging Science in Dentistry
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• v.51 no.1
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• pp.9-16
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• 2021

Purpose: The purpose of this study was to analyze the reliability of 7 panoramic radiographic signs for predicting proximity of the root apices of mandibular third molars to the mandibular canal using cone-beam computed tomography and to correlate these findings with the Pell and Gregory and the Winter classification systems. Materials and Methods: An observational, cross-sectional, descriptive study was conducted on 74 patients with bilateral impacted mandibular third molars. Four panoramic radiographic signs were observed in the tooth root (darkening, deflection, and narrowing of the root apices, and bifid apices), and another 3 in the mandibular canal (diversion, narrowing, and interruption of the mandibular canal). Cone-beam computed tomography images were analyzed to identify disruption and diversion of the mandibular canal and root deflection. Results: Binary logistic regression showed that only 4 of the 7 panoramic radiographic signs were able to predict proximity of the root apices of the mandibular third molars to the mandibular canal: darkening of the root, deflection of the root, narrowing of the root, and interruption of the mandibular canal(P<0.05). Conclusion: Darkening, deflection, and narrowing of the root, in tandem with the interruption of the mandibular canal on panoramic radiographs, indicate that cone-beam computed tomography should be performed when planning the extraction of impacted mandibular third molars. Proximity between mandibular third molars and the mandibular canal is correlated with the Winter classification.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.3
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• pp.257-263
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• 2015

Impacted teeth occur at higher frequencies in permanent than primary dentition. The most frequently affected teeth are the maxillary and mandibular third molars, whereas it is quite uncommon for the mandibular first molar to be impacted. Treatment methods for impacted teeth include continuous examination for independent eruption, surgical exposure, subluxation after surgical exposure, orthodontic traction, and surgical repositioning. If all of these treatments fail, tooth extraction may be considered. In the first case study, an 8-year-old boy was treated with surgical exposure, after which he was fitted with an obturator. His mandibular first molar then erupted successfully. In the second case, we treated a 12 year-old boy using orthodontic traction. This study describes children with tooth eruption disorders of the mandibular first molar in mixed dentition, and reports acceptable results regarding treatment of the impacted teeth.

• Imaging Science in Dentistry
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• v.53 no.4
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• pp.303-312
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• 2023

Purpose: This study investigated the prevalence of developmental and acquired pathologic conditions associated with impacted third molars (3Ms) in a Southern Brazilian population and evaluated whether demographic and tooth characteristics were correlated with the presence of bone or tooth lesions. Materials and Methods: Panoramic radiographs were assessed for developmental (bone-related) or acquired (tooth-related) pathoses associated with impacted upper or lower 3Ms. Data on tooth positioning, tooth development, and patient demographics were collected. A trained, calibrated postgraduate student evaluated all images. Binary and multivariate logistic regression models were used to assess associations between outcomes and the demographic and radiographic variables. The threshold for statistical significance was set at 5% (P<0.05). Results: The sample comprised panoramic radiographs from 2054 patients, predominantly female (59.2%), with a mean age of 27.2±11.5 years. Overall, 4066 impacted 3Ms were evaluated, revealing 471 (11.6%) developmental and 710 (17.5%) acquired pathoses. Among the developmental pathoses, 460 (95.2%) were indicative of dentigerous cysts. Male sex, lower 3M location, vertical or distoangular positioning, and incomplete root formation were associated with an elevated likelihood of developmental pathology. Lower tooth position, complete root formation, and partial eruption were linked to an increased probability of an acquired pathology in the third or second molar. Conclusion: The prevalence of pathologic conditions associated with impacted 3Ms was low. Male sex, lower 3M placement, horizontal or distoangular positioning, and incomplete root formation were associated with developmental pathoses, while lower tooth position, complete root formation, and partial eruption were related to acquired pathoses.

• 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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.5
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• pp.407-408
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• 2021

Extraction of impacted third molars is a routine procedure performed by oral and maxillofacial surgeons. However, extractions in middle-aged or elderly individuals are not easy, and there are several factors that need to be considered. These factors include decreased healing potential and the risk of complications increasing with age. In addition, third molars can often be fully or deeply impacted in middle-aged individuals, and pathologic changes, such as cysts, caries, or periodontitis of the adjacent second molar, can develop. Furthermore, the rate of ankylosis and systemic disease increases after middle age. It is considered that these factors acting alone or in combination increase the difficulty of extraction.

• Imaging Science in Dentistry
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• v.45 no.4
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• pp.233-240
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• 2015

Purpose: This study investigated maxillary third molars and their relation to the maxillary sinus using panoramic radiography and cone-beam computed tomography (CBCT) Materials and Methods: A total of 395 maxillary third molars in 234 patients were examined using panoramic radiographs and CBCT images. We examined the eruption level of the maxillary third molars, the available retromolar space, the angulation, the relationship to the second molars, the number of roots, and the relationship between the roots and the sinus. Results: Females had a higher frequency of maxillary third molars with occlusal planes apical to the cervical line of the second molar (Level C) than males. All third molars with insufficient retromolar space were Level C. The most common angulation was vertical, followed by buccoangular. Almost all of the Level C molars were in contact with the roots of the second molar. Erupted teeth most commonly had three roots, and completely impacted teeth most commonly had one root. The superimposition of one third of the root and the sinus floor was most commonly associated with the sinus floor being located on the buccal side of the root. Conclusion: Eruption levels were differently distributed according to gender. A statistically significant association was found between the eruption level and the available retromolar space. When panoramic radiographs showed a superimposition of the roots and the sinus floor, expansion of the sinus to the buccal side of the root was generally observed in CBCT images.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.722-727
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• 2006

Most of impacted teeth reported are permanent teeth. Impaction of primary tooth caused by primary failure of eruption is rare and the most of impacted primary tooth are second primary molars. The etiology of a primary molar impaction would appear to be a physical barrier, early ankylosis of the tooth, abnormal development of the primary molar germ or malposition of the successor bud. Transposition has been described as an interchange in the position of two teeth within the same quadrant of the dental arch. It is most commonly seen with canine and lateral incisor teeth, but is rarely associated with the primary dentition. The two cases show the transposition of impacted primary molar and the tooth germ of second premolar in their clinical and radiographic examinations. In case 1, lower second primary molar was deeply impacted inferiorly to the tooth germ suspected to be a second premolar. In case 2, impacted all second primary molars were positioned inferiorly to the tooth germs suspected to be the successors. We extracted all second primary molars under general anesthesia and the extracted tooth germs appeared to be second premolars.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.1
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• pp.29-35
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• 2017

Background: No study has compared lidocaine with articaine, each at a concentration of 4% and combined with epinephrine. The purpose of this study was to compare the effectiveness of 4% lidocaine with that of 4% articaine, with a concentration of 1:100,000 epinephrine added to each, in an inferior alveolar nerve block for surgery on impacted lower third molars. Method: This study was conducted at the Faculty of Dentistry, Mahidol University in Bangkok, Thailand. The randomized, single-blind, comparative split-mouth study was carried out in patients with symmetrically impacted lower third molars, as identified on panoramic radiographs. Each patient underwent surgery for the removal of the lower third molars by the same surgeon under local anesthesia at two separate visits, 3 weeks apart. The onset and duration of local anesthesia, intra-operative pain, surgical duration, and number of additional anesthetics administered were recorded. Results: The subjective and objective onset of action for the local anesthetics showed statistically significant differences (P < 0.05). However, the intra-operative pain, surgical duration, duration of local anesthesia, and number of additional anesthetics administered did not show statistically significant differences. Conclusion: The use of 4% articaine for the inferior alveolar nerve block was clinically more effective in the onset of subjective and objective anesthesia as compared with the use of 4% lidocaine. Based on the pain scores from the visual analogue scale, 4% lidocaine provided more analgesia during the procedure, and patients noted less intra-operative pain than with 4% articaine; however, the difference was not clinically significant.

• The korean journal of orthodontics
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• v.50 no.4
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• pp.268-277
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• 2020

This case report demonstrates two different uprighting mechanics separately applied to mesially tipped mandibular first and second molars. The biomechanical considerations for application of these mechanisms are also discussed. For repositioning of the first molar, which was severely tipped and deeply impacted, a novel cantilever mechanics was used. The molar tube was bonded in the buccolingual direction to facilitate insertion of a cantilever from the buccal side. By twisting the distal end of the cantilever, sufficient uprighting moment was generated. The mesial end of the cantilever was hooked over the miniscrew placed between the canine and first premolar, which could prevent exertion of an intrusive force to the anterior portion of the dentition as a side effect. For repositioning of the second molar, an uprighting mechanics using a compression force with two step bends incorporated into a nickel-titanium archwire was employed. This generated an uprighting moment as well as a distal force acting on the tipped second molar to regain the lost space for the first molar and bring it into its normal position. This epoch-making uprighting mechanics could also minimize the extrusion of the molar, thereby preventing occlusal interference by increasing interocclusal clearance between the inferiorly placed two step bends and the antagonist tooth. Consequently, the two step bends could help prevent occlusal interference. After 2 years and 11 months of active treatment, a desirable Class I occlusion was successfully achieved without permanent tooth extraction.