• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권4호
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• pp.445-449
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• 2008

Unerupted or erupted supernumerary tooth may cause crowding, diastema, cyst formation, resorption, and displacement or rotation of adjacent teeth. However, there are few studies about prognosis about the pathologic condition and expectation of spontaneous eruption. The object of this study is to evaluate factors predicting the spontaneous eruption of supernumerary tooth. 431 patients (346 males and 85 females, aged from 5 to 29 years) who visited our institution from 2002-2006 and were shown to have 471 mesiodentes was reviewed. Supernumerary teeth were classified inverted and not inverted state. In case of not inverted supernumerary tooth, eruption rate ac cording to length of supernumenary tooth, width of the tooth, angle between the tooth and incisor tooth, location (inside the incisor or not) and shape (conical or tubercle) were investigated. The regression model showed that length, width and angle were all important determinants of influencing the eruption of supernumerary tooth (p < 0.001, Pearson R: 0.619). There is no relation between shape and eruption of supernumerary tooth (p > 0.05). Location of mesiodens has an effect on eruption of supernumerary tooth (p < 0.01).

• 한국공작기계학회논문집
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• 제13권6호
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• pp.17-22
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• 2004

A study for investigating the effects of the cutting conditions (radial depth of cut feed per tooth) and the number of tooth on the side wall of prismatically milled workpiece is described. This study is available not only for understanding the geometrical characteristics of the end milled side wall but also for finding the optimal cutting conditions. In this work, the side wall geometry was characterized by the straightness and the location of maximum peak point. Through this study, it was revealed that the geometrical characteristics of the end milled side wall are strongly related to the material removal per tooth and the number of tooth.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권6호
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• pp.342-347
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• 2022

Objectives: The purpose of this study is to investigate the characteristics of dentigerous and radicular cysts that occur between deciduous and succeeding permanent teeth and to propose considerations for differential diagnosis of cysts at the treatment planning stage in the outpatient clinic. Materials and Methods: A total of 87 patients with a cystic lesion located between a deciduous tooth and the succeeding permanent tooth participated in the study. Twelve variables were analyzed to diagnose such a cyst. For data analysis, Fisher's exact test was used to determine the statistical significance of the variables. Results: Of the total 87 patients who participated in this study, 69 were diagnosed with dentigerous cysts and 18 were diagnosed with radicular cysts. Seven of the 12 differential factors analyzed in this study were statistically significant: age, location, symptoms, dental caries, endodontic treatment, delayed eruption, and size. Conclusion: Several criteria can be considered for diagnosis of dentigerous cysts or radicular cysts. Age, location, presence of symptoms and dental caries, previous endodontic treatment, cystic size, and delayed eruption of impacted permanent teeth are reliable factors that should be considered when diagnosing dentigerous and radicular cysts.

• 대한기계학회논문집A
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• 제27권2호
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• pp.223-230
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• 2003

Stress patterns are created in the plastic spur gear tooth body by introducing a hole or a steel pin to improve stress distribution. Static analysis using finite element method is carried out to show the effect. The result shows that maximum stress as well as tooth tip displacement is dependent on the size and location of a hole or a steel pin. When a hole located on the tooth center line, the maximum static stress level and the tooth tip deflection is always higher than that of a solid gear. But, a considerable reduction in the maximum stress and tooth tip displacement is achieved by insertion of steel pin.

• Imaging Science in Dentistry
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• 제42권3호
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• pp.197-200
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• 2012

Gemination, a relatively uncommon dental anomaly, is characterized by its peculiar representation as a tooth with a bifid crown and a common root and root canal. It usually occurs in primary dentition. To come across gemination in a supernumerary tooth is a rare phenomenon. The purpose of this paper is to present a unique case of hyperdontia wherein gemination in an impacted supernumerary tooth resulted in a trifid crown unlike the usual bifid crown. The role of conventional radiographs as well as computed tomography, to accurately determine the morphology and spatial location, and to arrive at a diagnosis, is also emphasized in this paper.

• Imaging Science in Dentistry
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• 제39권2호
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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)

• 대한치과의사협회지
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• 제52권5호
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• pp.281-290
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• 2014

Tooth eruption disturbance is seen commonly in mixed dentition or early permanent dentition. During this period of time, children experience the growth and development of craniofacial skeleton and dentition, so the impaction and eruption disturbance of permanent teeth make many problems in oral and maxillofacial areas. Eruption guidance of impacted tooth is not simple because many factors related to impaction are considered. Several factors such as etiology, tooth development stage, location of impacted teeth or eruption pathway, patient cooperation, etc. need to be taken into consideration in deciding the management of the impacted tooth. In the present study, it was assessed the etiology and impaction status of impacted tooth through various cases, and try to explain the treatment method to guide eruption by surgical exposure.

• International Journal of Oral Biology
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• 제46권4호
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• pp.200-207
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• 2021

In case of gingival recession and alveolar bone defects due to tooth loss for a long period of time in a single tooth in the maxillary anterior region, it is not easy to obtain aesthetic results with a single implant prosthesis. For aesthetic restoration, it is important to preserve hard and soft tissues through alveolar bone augmentation as well as restore harmony with adjacent teeth and soft tissues by placing the implant in an ideal location. In this case, an implant was placed using guided bone regeneration and a connective tissue graft simultaneously with immediate implantation after extraction from the maxillary anterior region where only residual root was left for a long period of time.

• Imaging Science in Dentistry
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• 제53권3호
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• pp.229-238
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• 2023

Purpose: Ectopic eruption can be defined as the emergence of a tooth in an abnormal location, where the tooth does not follow its typical eruption pathway. While ectopic eruption within the dentate region is well-documented in the literature, ectopic eruption in non-dentate regions is relatively rare. This study aimed to report 6 cases of ectopic teeth and present a systematic review of the English-language literature on ectopic teeth, emphasizing demographic characteristics, radiographic features, potential complications, and treatment options. Materials and Methods: A literature search was conducted using the PubMed, Medline, Web of Science, and Cochrane databases. The demographic data and radiographic findings of patients presenting with ectopic teeth were recorded. Results: The literature review yielded 61 cases of ectopic teeth, with patients ranging in age from 3 to 74 years. The findings from these previously reported cases demonstrated that the most common location for ectopic teeth was the maxillary sinus, which is consistent with this case series. The Pearson chi-square test was performed to evaluate the correlation between age and location of ectopic teeth, and the results were found to be statistically significant (P<0.05). However, no statistically significant relationship was observed between sex and the location of ectopic teeth. Conclusion: The distinct features of these cases warrant reporting. This study presents the first case of supernumerary teeth in the condyle without any associated pathosis. Another notable characteristic is the pre-eruptive resorption of 2 inverted supernumerary teeth ectopically located in the palate, which predisposes to sinus opacification.

• Journal of Oral Medicine and Pain
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• 제41권3호
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• pp.85-90
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• 2016

Purpose: The aim of this study was to develop an automated software to extract tooth and pulpal area from sectional cone-beam computed tomography (CBCT) images, which can guarantee more reproducible, objective and time-saving way to measure pulp/tooth volume ratio. Methods: The software program was developed using MATLAB (MathWorks). To determine the optimal threshold for the region of interest (ROI) extraction, user interface to adjust the threshold for extraction algorithm was added. Default threshold was determined after several trials to make the outline of extracted ROI fitting to the tooth and pulpal outlines. To test the effect of starting point location selected initially in the pulpal area on the final result, pulp/tooth volume ratio was calculated 5 times with different 5 starting points. Results: Navigation interface is composed of image loading, zoom-in, zoom-out, and move tool. ROI extraction process can be shown by check in the option box. Default threshold is adjusted for the extracted tooth area to cover whole tooth including dentin, cementum, and enamel. Of course, the result can be corrected, if necessary, by the examiner as well as by changing the threshold of density of hard tissue. Extracted tooth and pulp area are reconstructed three-dimensional (3D) and pulp/tooth volume ratio is calculated by voxel counting on reconstructed model. The difference between the pulp/tooth volume ratio results from the 5 different extraction starting points was not significant. Conclusions: In further studies based on a large-scale sample, the most proper threshold to present the most significant relationship between age and pulp/tooth volume ratio and the tooth correlated with age the most will be explored. If the software can be improved to use whole CBCT data set rather than just sectional images and to detect pulp canal in the original 3D images generated by CBCT software itself, it will be more promising in practical uses.