• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.395-401
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• 2003

In this paper, the dent printing phenomena and critical dent size which lead to premature failure of deep grooved ball bearing for automobiles are presented. The results of newly assembled test bearings showed that the ball dent size strongly affect the bearing life and inner ring raceways were the major failed parts in spite of using the dented balls. The dent printing phenomena are a root cause of premature failure, which was not reported until now. And there exist the critical ball dent size for given rolling bearings and operating conditions. So, the initial condition of tribologically mating parts should be treated as important as the failed body itself.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.4
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• pp.399-406
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• 2011

Traumatic injury on tooth occurs frequently among trauma patients, and mainly occurs on tooth with premature roots which influences pulp tissue, periodontal ligament, alveolar bone, and Hertwig's epithelial root sheath. According to the degree of trauma, a number of kinds of healing process can be observed, such as complete re-vascularization of pulp, root canal obliteration, growth suspension of root apex, and invasion of alveolar bone into root canal, and there can be some complications such as necrotic change of inflammatory root resorption and partial pulp necrosis due to pulp necrosis toward complete necrosis. In this clinical case, 3 patients who had traumatic injury showed root growth suspension and alveolar bone invasion into root canal due to proliferation of periodontal ligament cell and osteocyte at the base of extraction socket into pulp chamber because of the injury on Hertwig's epithelial root sheath. If intrusion of alveolar bone into root canal due to injury on Hertwig's epithelial root sheath after having traumatic injury doesn't show any complication, the pulp may be considered to have normal vitality and doesn't need any further treatment, therefore differential diagnosis is very necessary. However, it may be accompanied with suspension of root growth, therefore, additional trauma during the treatment of injured tooth should not be applied.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.172-179
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• 2015

The developmental mechanism of root formation is a complex process. Hereditary and environmental factors may affect the morphology of the developing root. A total of 12 cases was presented with permanent first molars with abberant root morphology. Clinically, these teeth appeared as a normal crown. However, radiographically, the root was slender, twisted and characterized by irregular lengths. In addition, root trunk length was shorter and pulp chamber was obliterated. In these cases, periapical radiolucency and loss of lamina dura were often observed. In 6 cases, an abnormal root of the primary second molars were also present, as well as root malformation of permanent first molars. In 3 cases, permanent central incisors also had a dysmorphic crown. These cases almost all had medical history, such as premature birth, brain infection or congenital heart disease in infants. The present paper describes cases of permanent first molars with an abnormal root that are rarely reported in literature. This case may intensify the variation in the permanent first molar and is intended to reinforce the clinician's awareness of rare morphology of the roots.

• Imaging Science in Dentistry
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• v.30 no.4
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• pp.287-292
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• 2000

A case of dento-maxillofacial abnormality involving a 10-year-old male patient with a history of esthesioneuro-blastoma is presented. This patient had been treated with 54 Gy /sup 60/Co-gamma-radiation to the nasal cavity for 6 weeks and 6 cycles of combination chemotherapy of Cyclophosphamide, Cisplatin, Adriamycin, VM-26 (Tenipo-side), and DTIC (Dacarbazine) when he was 16 months of age. Five years after cessation of cancer therapy, he was disease free and transferred for extensive dental care to Kyung Hee University Dental Hospital. A clinical and radiologic follow-up over last 4 years showed root stunting, premature closure of the root apices, microdontia, developmental arrest, small crowns, and partial anodontia. Maxillofacial morphology evaluated by cephalometric analysis showed deficiency of maxillary development.

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.178-181
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• 2013

Traumatic injuries to an immature permanent tooth may result in cessation of dentin deposition and root maturation. Endodontic treatment is often complicated in premature tooth with an uncertain prognosis. This article describes successful treatment of two traumatized maxillary central incisors with complicated crown fracture three months after trauma. The radiographic examination showed immature roots in maxillary central incisors of a 9-year-old boy with a radiolucent lesion adjacent to the right central incisor. Apexogenesis was performed for the left central incisor and revascularization treatment was considered for the right one. In 18-month clinical and radiographic follow-up both teeth were asymptomatic, roots continued to develop, and periapical radiolucency of the right central incisor healed. Considering the root development of these contralateral teeth it can be concluded that revascularization is an appropriate treatment method in immature necrotic teeth.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.1
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• pp.87-101
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• 2015

The premature loss of the mandibular primary canine is relatively frequent and a sign of the upcoming space problems in the transitional period. This situation is caused by the permanent lateral incisor resorbing the root of the primary canine during its eruption. Bilateral loss of primary canines in a crowded arch leads to the lingual tipping of the permanent incisors, with the consequent reduction in the arch perimeter and increase in overbite. When the loss of a primary canine is unilateral, tipping of the adjacent incisors occurs toward the space, resulting in midline deviation. In these situations, treatment possibilities, such as extraction of the antimeric tooth or placement of a passive lingual arch, can be applied; although there are some controversies concerning this. Most space problems with less than 4 mm can be resolved through preservation of the leeway space using sequential disking of the primary teeth and a passive lingual arch, regaining space or limited arch expansion in the late mixed dentition. In cases with 4~6 mm of space problems, arch expansion (A-P or transverse) can be applied. Space problems with more than 6 mm should be treated through diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth including serial extraction (guidance of eruption).

• BMB Reports
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• v.28 no.1
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• pp.6-11
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• 1995

A new lectin, named TRA, was purified from Trichosanthes kirilowii root by acid-treated Sepharose 6B, Mono-Q, and TSK-gel 3000SW column sequential chromatography. The lectin appeared homogeneous by native gel electrophoresis at pH 4.3 and gave two protein bands of Mr=31 and 28 kDa by SDS-PAGE. The N-terminal amino acid sequences of the polypeptides of TRA have not been reported in amino acid sequences of the lectins. TRA lectin formed a precipitate with asialofetuin, neuraminidase-treated fetuin. A sugar inhibition assay indicated that N-acetyl-D-galactosamine, among the monosaccharides tested, was the most potent inhibitor of TRA-induced hemagglutination. Asialofetuin showed a 260-times stronger inhibitory activity than N-acetyl-D-galactosamine. TRA lectin also showed agglutination with normal leukocytes and lymphoma cells, but not with premature hemopoietic cells. These results suggest that TRA is a novel plant lectin.

• The Journal of the Korean dental association
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• v.50 no.6
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• pp.322-328
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• 2012

Ectopic eruption of the permanent first molar is defined as the eruption of the tooth in an abnormal position or orientation. It may causes distal root resorption and premature exfoliation of the adjacent primary second molar and uncontrolled space loss is followed. Prolonged partial impaction of the permanent molar may also cause undetected caries or abscess formation of the neighbor teeth. The purpose of this paper is to provide a brief review regarding the etiology, classification, and different management techniques for correcting ectopic eruption of permanent first molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.555-561
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• 1998

Hypophosphatasia is a rare metabolic disorder which manifests characteristics such as abnormal mineralization of bone and dental tissues, diminished serum and tissue alkaline phosphatase, and increased urinary secretion of PEA. It inherited as an autosomal recessive or dominant trait and occurs in all races. In general, hypophosphatasia can be classified in 4 subtypes which are the perinatal, infantile, childhood, adult type depending upon the age at presentation and severity. In young children with Hypophosphatasia the long bones show irregular defects, and the skull showes poor calcification. In older children with premature closure of the skull sutures there may be multiple lucent area called gyral or convolutional markings, described as resembling beaten copper, presumably resulting from increased intracranial pressure. Examination of the jaws reveals a generalized lucency of the maxilla and mandible. the cortical bone and lamina dura are thin, and the alveolar bone may be deficient. Clinical features of Hypophosphatasia include premature loss of deciduous teeth, especially incisors, hypoplasia or aplasia of root cementum, enamel hypoplasia, irregular calcification of dentin, large pulp chamber, and resorption of marginal alveolar bone and roots. Our report involves a patient with a chief complaint of early loss of both Mx. and Mn. deciduous incisors. After conducting a through clinical and radiographic examination this patient was referred to pediatrics under the suspicion of hypophosphatasia, the diagnosis proved to be correct and successful results were accomplished through a denture made to improve esthetics and function.

• Journal of Plant Biotechnology
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• v.5 no.4
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• pp.239-244
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• 2003

A protocol has been developed for rapid large scale clonal propagation of an aromatic endangered medicinal plant, Hemidesmus indicus R. Br. with the elimination of the problems such as premature leaf fall and callus formation during caulogenesis and rhizogenesis. Multiple shoots were induced from shoot tip and nodal explants on Murashige and Skoog (MS) medium supplemented with 1 mg/L Benzylaminopurine (BAP) and 0.5 mg/L Napthaleneaceticacid (NAA). Addition of 15 mg/L adenine sulphate to the above medium checked leaf abscission completely, reduced the time required for caulogenesis and restored morphogenetic potential after several subcultures. The in vitro grown propagules were rooted in 1/2 MS medium supplemented with 2 mg/L Indolebutyric acid (IBA) +1 mg/L NAA and sucrose 0.7% (w/v). Addition of charcoal at 100 mg/L to the rooting medium quickened root initiation with a complete check on callus formation. The effect of sucrose concentration on both caulogenesis and rhizogenesis was also studied. The resultant plantlets were acclimatized and grown in fields where ninety eight percent of the rooted shoots survived and grew normally. The estimation of the secondary metabolite content in the shoots of the regenerated plant and the mother plant indicated that the concentration of the three secondary metabolites lupeol, vanillin and rutin was similar.