• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.173-182
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• 1995

The purpose of this study was to evaluate the adaptability of light-cured glass ionomer cement to cavity walls. Class V cavities were prepared on the labial surfaces of extracted bovine incisor teeth. The cavities were restored with Fuji II as self-cured glass ionomer cement and Fuji II LC, Vitremer as light-cured glass ionomer cement. Fluorescent markers (fluoreceine and rhodamin B) were incorperated into liquid and primer for a better image of microscopic observation. Restored teeth were sectioned by longitudinal and labiolingual direction. The adaptability at the tooth-restoration interface was assessed incisally, axially and cervically by confocal scanning laser microscope. Following results were obtained : 1. Chemical-cured glass iomomer cement restoration showed close adaptation on the all of the cavity walls, but, cracks formed within the cement. 2. Light-cured glass ionomer cement restoration was well adapted to the cavity walls, but showed crack in the cement adjacent to axial dentinal wall. 3. There' was no significant difference in adaptability between two light-cured glass ionomer cement restorations.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.371-378
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• 2011

Transposition is defined as a dental anomaly manifested by a positional interchange of 2 adjacent teeth within the same quadrant of the dental arch. Maxillary canine-first premolar [Mx4-3] transposition is the most frequent tooth transposition reported in the literature. In this case report, an orthodontic correction of a transposition of the maxillary left canine and first premolar with the help of palatally located mini-implant anchorage is described. Esthetic and occlusal evaluations suggested alignment of the transposed teeth to their correct anatomic positions in the dental arch. The clinical result at the end of the treatment was satisfactory. Alignment was obtained, and intercuspation was adequate. Nevertheless, the maxillary canine showed facial recession, probably because it was initially positioned buccally. Supporting tissue was examined after treatment and no alveolar bone damage was observed.

• Journal of Biosystems Engineering
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• v.17 no.2
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• pp.171-176
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• 1992

This study was intended to develop the design theory of the threshing unit of a head-feeding rice combine. It may be applied for various combining capacities with different cutting widths and forward speeds. Design factors in the theoretical development are : (1) dimensions of the threshing drum, (2) tooth approching angle, (3) distance between the adjacent teeth on their spiral setting line, (4) number of spirals, and (5) total number of teeth on the drum. A computer simulation program was developed to predict the proper dimensions for the threshing drum and tooth arrangement. A simulation for the prospective combine with varied capacities was also demonstrated. The parameters analyzed in the developed design theory were shown to be consistent with those of existing combines.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.548-555
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• 2008

Dentigerous cyst is the most common type of odontogenic cyst followed by radicular cyst. Most of dentigerous cysts originate from the permanent dentition and a few of them are associated with mesiodens. The complications of a dentigerous cyst associated with mesiodens are eruption abnomalies of adjacent teeth, root resorption, displacement, rotation, diastema and the secondary infection of the cyst due to adjacent teeth. The treatment of a dentigerous cyst of a maxillary mesiodens is to enucleate a cyst with a mesiodens. Otherwise, when it is close to adjacent teeth, a cyst is to reduce the through marsupialization after removing a mesiodens. There are numerous studies on dentigerous cysts and mesiodentes alone; however, the studies on the association of the two are rare. These are case reports about patients with mixed dentition whose dentigerous cyst of a maxillary mesiodens had been removed. After removal, the patients have been regularly checked up and shown satisfactory progress.

• Journal of the korean academy of Pediatric Dentistry
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• v.21 no.2
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• pp.491-495
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• 1994

The ectopic eruption is defined rise to be abnormal eruption, which gives to displacement of the teeth and abnormal root resorption of adjacent teeth. The ectopic eruption of first permanent molar is approximately 2-4% of the population, most of them are in the maxilla, rarely in the mandible. In the case of the second permanent molars, most of them are found in the mandible for the reason of the arch length discrepancies and large size of the teeth. The ectopic erupted molars should be treated early in order to coordinate normal growth pattern and to obtain good occlusal support. So, this should be early diagnosed and treated. But, ectopically erupting molars are often self-corrected, hence periodic follow-up is required. The methods of the treatment are largely classified into surgical, surgical-orthodontic, and orthodontic method. Especially in orthodontic method, they are divided as follows; appliances that is positioned at the contact point for unlocking and the distal movement, fixed and removable appliance that is connected to more than one tooth, and occlusion guiding method after disking or extraction of the second deciduous molar. The report presents the good results in treating patients, whose chief complaint was ectopic eruption of mandibular permanent molars.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.1
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• pp.7-21
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• 1994

Fifty-two cases of traumatic bone cysts in 50 patients were analysed clinically and radiologically. The obtained results were as follows; 1. Women showed a slightly higher incidence than did men (56% of patients) and the average age proved to be 18.6 years. 2. The majority of the cases were asymptomatic. being detected incidentally. and over the half of the cases occurred in the mandibular symphyseal region. 3. All cases were unilocular and the largest diameter of the lesions varied from 1 to 10㎝, mean 3㎝. 4. Some degree of marginal condensation was present in 28 cases and 23 cases presented pencil-sketch appearance. 5. Many anatomical cortical plates (especially, mandibular inferior cortex and lamina durae) consisted of the margin of the lesions partly. 6. Erosive change of the mandibular inferior cortex was caused by 12 cysts, but cortical expansion only by 3 cysts including 2 cases of buccal expansion. 7. The lesion enveloped the roots of the adjacent teeth in 27 cases and scalloping was present between roots in 17 cases. 8. Lamina dura of the teeth was destroyed by only 1 cyst, and in 1 case root resorption was noticed. But there was no divergence of the roots of teeth.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.119-126
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• 2006

Gerotor hydraulic motor is widely used in hydraulic systems due to its low speed, high torque output and compactness in rotational direct driving of a heavy weight. Gerotor is a Planar mechanism consisted of a pair of rotor and circular teeth of stator assembly which forms a closed space, so called a chamber. The motion of rotor relative to the circular tooth is produced by the pressure difference of hydraulic operating fluid between the adjacent chamber. As all active contact points of rotor and circular teeth are subjected to very high sliding friction, a reduction in the performance of the gerotor hydraulic motor can not be avoided. Therefore, the core design parameters of gerotor profile used in hydraulic motors is to minimize a friction force by high contact stresses. The analytical design method of gerotor profile, based on envelope of a family of curves, is proposed. In this study, the influence of the tip clearances on three critical contact points between rotor and circular teeth of stator assembly has been explored by experimental data in this paper. At the same time a improvement method to reduce the friction force is proposed and the tip clearances on three critical points for getting an optimum gerotor profile are also analyzed.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.121-130
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• 2023

In children, large odontogenic cysts affect adjacent anatomical structures as well as displace developing permanent teeth. Odontogenic cysts are treated via enucleation or marsupialization. This case reports a 5-year-old boy and a 10-year-old boy who have not only displaced 3 or more permanent teeth but also elevated the maxillary sinus floor due to the large size of the cyst in the maxillary anterior region. In both cases, marsupialization was selected to minimize complications. After marsupialization, a customized acrylic obturator, window opening, and orthodontic traction for eruption guidance were gradually attempted, and it showed a good prognosis, so we report these cases.

• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.1
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• pp.66-79
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• 2024

This study aimed to assess the prevalence and distribution pattern of dental anomalies in the permanent teeth of patients with non-syndromic cleft lip with or without cleft palate. Additionally, it aimed to compare differences in dental anomalies between cleft and non-cleft areas, considering gender and cleft phenotype. Panoramic radiographs of 164 patients diagnosed with non-syndromic orofacial clefts were retrospectively analyzed by a single examiner to confirm dental anomalies. The dental anomalies investigated included tooth agenesis, supernumerary teeth, microdontia, rotation, ectopic eruption, and enamel hypoplasia. Cleft phenotypes were categorized into 7 types based on medical and dental records. A significantly higher prevalence of supernumerary teeth was observed in males than females within non-cleft areas (p = 0.017), with no significant differences in other dental anomalies. In non-cleft area, patients with cleft palate exhibited a high prevalence of tooth agenesis (p < 0.0001) and microdontia (p = 0.012) compared to other cleft phenotypes. Maxillary incisor rotation was closely associated with adjacent tooth agenesis in unilateral cleft lip and palate cases (p = 0.034). This study suggests that the additional subphenotype based on dental anomalies in patients with orofacial cleft may serve as applicable clinical markers.

• Journal of Oral Medicine and Pain
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• v.48 no.4
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• pp.169-173
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• 2023

Hemangioma is a lesion characterized by vascular proliferation of endothelial origin, manifesting neoplastic features. The occurrence of central hemangioma in the oral and maxillofacial region is exceptionally rare, and in two-thirds of cases, it is predominant in the mandible rather than the maxilla. The main symptoms and signs associated with central hemangiomas include pulsation, bone expansion, bruit, teeth displacement, and root resorption of the adjacent teeth. Bleeding may manifest periodically from the sulcus surrounding the affected teeth, particularly when accompanied by hypermobility in the primary dentition. One of the most noteworthy complications is the potential for severe bleeding during tooth extraction or surgical procedures conducted in proximity to unrecognized hemangiomas. Such situations may pose a life-threatening risk. Taking this into consideration, we present two cases of central hemangiomas in adolescent patients who sought consultation, with subsequent embolization performed by the Department of Radiology in Chosun University Hospital.