• Journal of the korean academy of Pediatric Dentistry
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• v.5 no.1
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• pp.12-18
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• 1978

The author has observed the ectopic eruption pattern on oblique cephalogram of 195 children. (5years: 78, 6 years: 58, 7 years: 59). The results were as follows; 1) Making a comparison between hold type and jump type of ectopic eruption, there are 4 cases in Hold type, 5 cases in jump type. 2) Making a comparison of ectopic eruptin between male and female, there are 7 cases in male, 2 cases in female. 3) Making a comparison of ectopic eruption between right side and left side, there are 5 cases at right side, 4 cases at left side. 4) Making a comparison of ectopic eruption among 5 years to 7 years, there are 4 cases in 5 years, 3 cases in 6 years, 2 cases in 7 years. 5) The prevalence of ectopic eruption of the maxillary first molar was 4.61%. 6) Normal eruption angle of the maxillary first molar is prevailing in $80^{\circ}{\sim}85^{\circ}$.

• Journal of Korean Dental Science
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• v.7 no.1
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• pp.25-30
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• 2014

Subcutaneous emphysema and pneumomediastinum is a relatively uncommon phenomenon. It may occur secondary to dental treatment using high-speed air turbine handpieces, especially after extraction of tooth. Subcutaneous emphysema is often limited only to the areas of head and neck, but also can involve deeper structures. Thorough examination and conservative treatment of these problems are essential in preventing life-threatening complications such as airway obstruction and mediastinitis. The subject of this report is a 57-year-old woman with subcutaneous emphysema and pneumomediastinum during the extraction of maxillary third molar using high-speed air turbine handpiece. If there isn't any appropriate measure, severe complications may occur. Therefore it is important to be well-informed of proper diagnosis and treatment. This article shall present a case report with literature review.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.290-300
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• 2016

Objective: This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods: Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results: An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions: The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.111-126
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• 1998

In this study, radiographic evaluation was made using panoramic radiography and cross-sectional tomography of SCANORA/sup (R)/ in male and female adults in their 20's on the relationship between the maxillary sinus floor and the apex of the maxillary molar, to test the accuracy and effectiveness of the cross-sectional tomography, and to use this information in the assessment of preop. and postop. root canal treatment, apical surgery, extraction and implantology. Forty-one adults with an average age of 24.4 years were studied using panoramic radiography and cross-sectional tomography. In panoramic view and cross-sectional view, the position of the apices of maxillary molars were classified as separated, contacted, or protruded type; the general shape of the maxillary sinus floor was evaluated horizontally and vertically from cross-sectional tomography. The accuracy of each radiography was tested using maxilla from 5 fresh cadavers from the Anatomy Lab at Yonsei University Dental College, and panoramic view and cross-sectional tomography were taken in the same condition as with the patients. The results were as follows: 1. Panoramic view and cross-sectional view were taken in the maxilla specimen, and the actual distance between the maxillary sinus floor and the tooth apices were measured in the specimen; the median values of the distance from the tooth apices to the maxillary sinus floor in the panoramic view, cross-sectional view and in the actual maxilla specimen were 2.83 mm, 4.51mm, and 4.l5mm, respectively. In the cross-sectional view, the measured distance was close to the actual distance but in the panoramic view, the measured distance was far from the actual distance. 2. When the results of the panoramic view and cross-sectional view were compared, 40.5％ of the results agreed with each other in the two radiographic methods and buccal roots of the 2nd molar were the closest to the maxillary sinus floor in the cross-sectional tomography. 3. In cross-sectional view, when the vertical relationship of the maxillary sinus floor and maxillary roots was assessed, in 1st molars, type II (the sinus floor that extends down to the buccolingual furcation area) was predominant, while in 2nd molars, type I (the sinus floor located above the level connecting the buccal and lingual apices) was predominant. In the horizontal relationship, in 1st molars, type II (the lowest floor of the maxillary sinus located in between the buccal and lingual roots) was predominant; in 2nd molars, type I (the lowest floor of the maxillary sinus located on the buccal side of the buccal roots) and type II appeared in similar frequency. In conclusion, the SCANORA/sup (R)/ cross-sectional tomography was more effective than the frequently used panoramic view, in that the relationship of the maxillary molars and maxillary sinus floor can be evaluated more accurately and the buccolingual cross-sectional view can also be observed. And maxillary sinus floor that was close to maxillary 2nd molar had tendency to be located on buccal side than that close to 1st molar. Therefore, cross-sectional tomography is an effective and accurate method to evaluate the position of the teeth in relation to the sinus floor preoperative and can be easily used to diagnose localized periapical lesions. Also, the image quality obtained was quite satisfactory.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.4 no.1
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• pp.45-57
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• 1974

This report based on 300 cases of serious diseases in maxillofacial region by radiograms seen at the department of dental radiodontics, infirmary school of dentistry, Kyung Hee University from October 1971 to August 1974. The maxillofacial diseases were analysed upon the following items, such as 1) the frequency of dominant diseases, 2) sex-ratio of male to female, 3) predominant region of diseases, 4) comparison with the age, 5) the incidence of diseases in relative to the individual teeth. The results were obtained as follows. 1) Among the total of 300 cases of the patients, the frequency of dominant diseases of patients were fractures of facial bone (44.3±2.87%), inflammatory diseases (22.7±2.39%), cysts (11.1±1.62%), tumors (10.7±1.77%), maxillary sinusitis (7.9±1.56%), temporomandibular joint disorders(3.3±1.05%) in the order. 2) The ex-ratio of male to female in occurence of jaw fractures were 7.3:1, temporomandibular joint disorders were 2.1:1, inflammatory diseases were 1.8:1, maxillary sinusitis were 1.7:1, but tumors were equal to 1:1, while cysts were 1:1.2 in sex difference. 3) The predominant region of mandibular fractures were symphysis(17.3±3.27%), canine region (15.0±3.09%), and angle region (14.3:±3.04%) in the order. Inflammatory diseases were occured frequently in mandible and it's left side were a little dominant. Odontogenic cysts were observed frequently in maxilla, but regardless of right and left. Carcinomas were involved most frequently in maxilla, while sarcomas and ameloblastomas in mandible. Frequency of the maxillary sinusitis were dominant right side and molar area, also temporomandibular joint disorders were right side. 4) To study comparison with the age jaw fractures showed the highest ratio at the 2nd decade(32.3±4.06%), and 3rd decade (27.8±3.89%), 4th decade (19.6±3.44%), 6th decade (9.0±2.47%), 5th decade(6.0±2.06%), 1st decade (5.3±1.95%) in the order. But 7th decade were not involved entirely. Frequency of the inflammatory diseases were the highest in the age group of 3rd decade (28.0±5.44%), and those of cysts were 5th decade (24.2±7.22%), temporomandibular joint disorders were 3rd decade (60.0±15.49%). Tumors were occured frequently over the 4th decade especially malignint tumors over the 5th decade, but maxillary sinusitis were rearless of age except for 2nd decade. 5) About the incidence of diseases in relative to individual teeth, fractures of facial bone were most frequently involved the maxillary and mandibular anterior teeth, and mandibular 3rd molar region. Cysts were maxillary anterior region inflammatory diseases were mandibular molar region maxillary sinusitis were maxillary 1st molar, region but tumors were regardless of individual teeth.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.555-567
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• 1994

The purpose of this study is to observe the effect of high pull headgear on the craniofacial structures of mixed dentition with Class II malocclusion. The cephalometric headplates of 16 children treated by high pull headgeaar during 6 months and 18 children during 12 months were traced, digitized and statistically analyzed. The results were as follows. 1. Inhibition of foreward growth of maxilla was observed in both group. 2. Clockwise rotation of maxilla was observed in both group. 3. There were distal movement of maxillary 1st molar and inhibition of alveolar bone growth of maxilla. 4. There was compensatory extrusion on mandibular 1st molar. 5. The ratio of anterior facial height to posterior facial height was almostly not changed. In the treatment plan of C II malocclusion by high pull headgear, ire must prevent the mandibulasr 1st molar from extruding and for orthopedic effect, at least 6 months is needed.

• 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.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.556-562
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• 2009

Ectopic eruption of the maxillary first permanent molar means that the molar erupts out of the normal position and is arrested in its eruption by the second primary molar. This local eruption disturbance results in a premature atypical resorption on the distal part of the second primary molar. In most irreversible cases, the second primary molar is lost prematurely, either by spontaneous exfoliation or by extraction, In cases of doubt as to whether the eruption is of the irreversible type or not, careful radiographic observation period for a few months would be valuable in evaluating the possibilities of the tooth's freeing itself. The purpose of this study was to determine the characteristics and occurrence of the ectopic eruption of the maxillary first permanent molar. A descriptive, observational, retrospective study was done using the radiographs of 25 conseutive patients, who were in the first phase of mixed dentition. A method was designed to evaluate the amount of pathologic resorption of the second maxillary primary molar and the mesial angulation of the first permanent molar. The study showed that the most important etiologic factor was the eruption path or mesial angulation of the first permanent molars relative the chosen reference lines.

• The korean journal of orthodontics
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• v.41 no.3
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• pp.191-199
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• 2011

Objective: The purpose of this study was to investigate the stress distribution on the orthodontic mini-implant (OMI) surface and periodontal ligament of the maxillary first and second molars as well as the tooth displacement according to the OMI position in the dragon helix appliance during scissors-bite correction. Methods: OMIs were placed at two maxillary positions, between the first and the second premolars (group 1) and between the second premolar and the first molar (group 2). The stress distribution area (SDA) was analyzed by three-dimensional finite element analysis. Results: The maximal SDA of the OMI did not differ between the groups. It was located at the cervical area and palatal root apex of the maxillary first molar in groups 1 and 2, respectively, indicating less tipping in group 2. The minimal SDA was located at the root and furcation area of the maxillary second molar in groups 1 and 2, respectively, indicating greater palatal crown displacement in group 2. Conclusions: Placement of the OMI between the maxillary second premolar and the maxillary first molar to serve as an indirect anchor in the dragon helix appliance minimizes anchorage loss while maximizing the effect on scissors-bite correction.

• Restorative Dentistry and Endodontics
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• v.28 no.3
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• pp.232-240
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• 2003

This study is to investigate the canal system in the mesiobuccal root of the maxillary first molar. 61 maxillary first molars were randomly selected. Serial transverse sections were made perpendicular to the long axis of the mesiobuccal root. Each section was placed in 3% sodium hypochlorite for 24 hours and rinsed in water and dried. The resected surface was stained with 2% methylene blue dye and examined with stereomicroscope. 1 Canal configuration analysis showed that 36.1% of the specimen classified as type I, 16.4% as type II , 37.7% as type III and 9.8% as type IV. 2. Type II canal was merged in one canal within 1 to 4mm of the apex. 40% of type II canal converged at 2mm of the apex. 3. Type IV canal was divided into two canal within 2 to 4mm of the apex. 66.6% of type IV canal branched off at 2mm of the apex. 4. None of the sections had more than two main root canal. 5. 48.4% of the sections in 3mm with two canals contained an isthmusand more than 70% with two canals has isthmus at 4 to 5mm sections. 63.9% of the mesiobuccal root of maxillary first molar had two canaland 76.5% of sections with two canals in 5 MM had an isthmus. Because of this complexity the clinician should always search for extra canal carefullyand root canal system, including an isthmus, should be cleaned and shaped completelyand obturated three dimensionally for successful endodontic treatment.