• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.205-215
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• 2008

The purpose of this study is to evaluate at which stage of tooth germ would develop into normal calcification and hence to increase the success rate of transplantation. Therefore, tooth germs on the 15th, 17th embryonic day and the 3rd day of birth were separated for allotransplantation into maxilla of adult rat of 11 weeks. Calcification processes were analyzed radiographically and histopathologically at 4 weeks and 8 weeks after allotransplantation. The results are as follows: 1. Allotransplanted tooth germ at 4 weeks and 8 weeks showed delayed calcification compared to that of normal odontogenesis. 2. At 4 weeks, abnormal calcified tissue, such as odontoma and ankylosis of osteodentin with surrounding alveolar bone were observed. 3. At 8 weeks, allotransplanted tooth germs of the 15th and 17th embryonic day showed calcification and osteodentin surrounded by periodontal ligament. 4. At 8 weeks, allotransplanted tooth germs of the 3rd day of birth showed calcification composed of cementum and osteodentin. In this study, we observed small sized and amorphous calcified tissue from allotropic allotransplantation of tooth germs. Since these calcified tissue were underdeveloped and shaped irregularly, for calcification into normal tooth form, further study needs consideration about the reduction of surgical trauma, developmental stage of transplanted tooth germ, blood supply from recipient site, fixation method in transplanted site and period of transplantation.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.1025-1033
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• 2019

Although magnetic resonance imaging without linear hardening of CT is recognized as a method of obtaining high contrast of tissue and excellent resolution image in brain disease and head and neck examination, magnetic susceptibility artifact is generated in case of metal implants in the oral cavity, which is an obstacle to image diagnosis. Therefore, an effort was made in this thesis to find a method to reduce artifacts caused by dental implants and prosthesis in MRI. Implant-induced artifacts in magnetic resonance imaging showed that the signal size increased with shorter TE in GE technique and was inconsistent with water temperature change. In SE technique as well, the signal size of water was generally higher than that of air, but the signal to noise ratio (SNR) was not different by air and temperature. In EPI technique, images with fewer artifacts were obtained quantitatively and qualitatively when there was more water than air, and the signal to noise ratio was measured the highest, especially at water temperatures of 20° and 30°. In conclusion, when examining using the EPI technique rather than the SE or the GE technique, obtaining brain diffusion using a 20° and 30° water bag reduces the magnetic susceptibility artifacts caused by implants and prosthesis, suggesting that it may provide images with high diagnostic value.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.3
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• pp.207-215
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• 2017

Many factors should be considered for successful denture treatment at edentulous patients: support, retention, stability, occlusion, esthetics, etc. The patient who has severely absorbed residual ridges, however, treatments are challenging to satisfy those factors. The dentures that use anatomic artificial teeth show good mastication efficiency and esthetics but, can easily lose stability at absorbed ridges. On the contrary, the dentures that use non-anatomic artificial teeth perform better stability but, lower masticatory efficiency and esthetics at absorbed ridges. The lingualized occlusion, using both anatomic and non-anatomic teeth, introduced for compromise those of the pros and cons. At lingualized occlusion, buccal cusps of the teeth do not contact on centric relation. Therefore, direction of the occlusal force towards lingually, then stability of dentures increases. This case report shows the results of the treatment flat residual ridges using complete dentures with ligualized occlusion to increase dentures stability and satisfactory of the patient.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.189-195
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• 2003

The objective of this study is to improve the optical sensitivity of laser fluorescence for detection of incipient enamel caries. An incipient carious lesion was formed in various stages by placing an enamel specimen of a bovine tooth in STPP demineralization solution. After measuring the optical density of the lesion surface by laser fluorescence induced by argon laser and various alter of yellow(500-520nm), amber(520-540nm), orange(540-560nm), and red(560-580nm), the specimen was cut vertically to measure the depth of the lesion using a polarizing microscope. SAS statistical program was used to analyze the relationship between the optical density of the lesion suface and the depth of the lesion. The results were as follows: 1. The optical density of early carious lesion, measured by laser fluorescence with amber and orange filter, and lesion depth observed by polarizing microscope, were increased as demineralization time increased. 2. The correlation coefficient between optical density of the lesion surface and the histological depth of the lesion was the highest in orange filter(r=0.49), followed by amber(r=0.32), yellow(r=0.13) and red(0.01). 3. Regression analysis showed that the most linear relationship between the optical density and the lesion depth was existed in orange filter group. In regard above results, laser fluorescence could be considered to be reliable for optical diagnosis of dental caries.

• The Science & Technology
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• v.35 no.12 s.403
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• pp.6-9
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• 2002

명왕성 밖에서 거대한 얼음-돌 천체 발견/남공 상공 오존층 작아져/가장 아름다운 물리학 실험 10가지/곤충으로 박테리아 퇴치/인공의 뇌운으로 산불 끈다/전기자동차용 리튬이온전지 개발/박테리아 위성 발사로 생명체 기원 실험/대용량 원자 메모리 기술 개발/세계에서 가장 높은 발전 타워/원자파 레이저로 화산폭발 예측/새 치아를 생물학적으로 자라게 한다/강하고 견고한 에어로겔 제조/유리 속의 분자도 구조를 가졌다

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.292-292
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• 2004

치과용 임플란트(Implant)란 상실된 자연치아를 대신하여 골 내에 매식하는 인공치근을 말한다. 임플란트는 인접 자연치아의 보호, 심미적 안정 등의 장점으로 인해 그 수요가 늘어나고 있으며, 단일치아 임플란트의 경우, 부분 무치악 환자들에게 있어서 우수한 치의학적 해법이 되어왔다. 대부분의 임플란트는 두 개 이상의 구성요소로 이루어져 있으며, 각각의 구성요소는 나사에 의해 결합되어 있다. 많은 연구결과를 통해, 임플란트의 나사 풀림 현상(Screw loosening)은 임플란트와 관련하여 가장 흔한 문제로 나타나고 있다.(중략)

• Journal of Biomedical Engineering Research
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• v.14 no.3
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• pp.257-264
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• 1993

A study on the biocompatibility of two types of new glass-ceramics materials, metal disc and dental porcelain that were already made for dental artificial tooth in the previous study, have been attempted. The chemical behavior and the Victor's hardness change in she artificial saliva and Ringer's solution have been also investigated. From the experiment of Implantation of glass-ceramics Into dorsal subcutaneous tissue of Sprague-Dawley rats, glass-cerarmics did not show any particular system of rejection for histrocompatibility.

• Journal of Digital Convergence
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• v.12 no.2
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• pp.439-446
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• 2014

To evaluate the effects of an artifact by metal material for orthodontics in Magnetic Resonance Image (MRI) examination, wires and brackets used in orthodontics were selected and compared. Using a head coil, a $T_2$-weighted image, $T_1$-weighted image and FLAIR image were obtained. With obtained images, the sizes of the artifacts were measured and compared using Image J Program. In the research, the material with the biggest artifact in the wires and brackets for orthodontics was stainless steel wire. In the future, selecting and developing metal for correction should be considered also in other fields along with the purpose of orthodontics.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.325-333
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• 2001

Optimal orthodontic treatment could be possible when a orthodontist can predict and control tooth movement by applying a planned force system to the dentition. The moment to force(M/F) ratio at the bracket, has been shown to be a primary determinate of the pattern of tooth movement. As various n/F ratios are applied to the bracket on the tooth crown, strain distribution in periodontium can be changed, and the center of rotation in tooth movement can be determined. It is, therefore, so important in clinicalorthodontics to know the strain distribution in a force system of a M/F ratio. The purpose of this study was to analyze the strain distribution in orthodontic force system by strain gauge attached to tooth root, and to evaluate the usage of the method. For this study, an experimental upper anterior arch model was constructed, where upper central incisors, on the root surface of which, 8 strain gauges were attached, were implanted In the photoelastic resin, as in the case of 4mm midline diastema. Three types of closing of upper midline diastema closure were compared : 1. with elastomeric chain(100g force) in no arch wire, 2. elastomeric chain in .016“ round steel wire, 3. elastomeric chain in .016”x.022“ rectangular steel wire. The results were as follows. 1. Strain distributions on labial, lingual, mesial and distal root surface of tooth were able to be evaluated with the strain gauge method, and the patterns of tooth rotation were understood by presuming the location of moment arm. 2. Extrusion and tipping movement of tooth was seen in closing in no arch wire, and intrusion and bodily movement was seen with steel arch wire inserted.

• Journal of the Korean Society of Radiology
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• v.10 no.8
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• pp.629-635
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• 2016

ACR phantom for quality control of magnetic resonance imaging equipment can evaluate magnetic resonance imaging picture quality through various structures within the phantom. In this study, percent Signal Ghosting and Slice position accuracy of imaging could be analyzed by attaching implant and the wire for correction of tooth using ACR phantom in Head coil of 3.0T equipment. In the T1 weighted imaging of the first slice and the eleventh slice of implant, the slice position accuracy appeared to be good in ingress bandwidth 300, and it was good in ingress bandwidth 130 when wire for correction was attached. Percent Signal Ghosting in the seventh slice of SE T1 weighted imaging, implant and wire for correction added all appeared to be good when ingress bandwidth was 230. It is thought that in case of implant dental prosthesis patients in brain exam using magnetic resonance imaging, optimum image can be obtained by changing ingress bandwidth.