• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2367-2370
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• 2014

"Cat's eye"-shaped $[^{57}Co]CoO@SiO_2$ core-shell nanostructure was prepared by the reverse microemulsion method combined with radioisotope technique to investigate a potential imaging agent for a single photon emission computed tomography (SPECT) in nuclear medicine. The core cobalt oxide nanorods were obtained by thermal decomposition of $Co-(oleate)_2$ precursor from radio isotope Co-57 containing cobalt chloride and sodium oleate. The $SiO_2$ coating on the surface of the core cobalt oxide nanorods was produced by hydrolysis and a condensation reaction of tetraethylorthosilicate (TEOS) in the water phase of the reverse microemulsion system. In vivo test, micro SPECT image was acquired with nude mice after 30 min of intravenous injection of $[^{57}Co]CoO@SiO_2$ core-shell nanostructure.

• Restorative Dentistry and Endodontics
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• 제46권1호
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• pp.2.1-2.8
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• 2021

Objectives: New premixed bioceramic root repair materials require moisture for setting. Using micro-computed tomography (micro-CT), this study evaluated the filling ability and volumetric changes of calcium silicate-based repair materials (mineral trioxide aggregate repair high-plasticity [MTA HP] and Bio-C Repair, Angelus), in comparison with a zinc oxide and eugenol-based material (intermediate restorative material [IRM]; Dentsply DeTrey). Materials and Methods: Gypsum models with cavities 3 mm deep and 1 mm in diameter were manufactured and scanned using micro-CT (SkyScan 1272. Bruker). The cavities were filled with the cements and scanned again to evaluate their filling capacity. Another scan was performed after immersing the samples in distilled water for 7 days to assess the volumetric changes of the cements. The statistical significance of differences in the data was evaluated using analysis of variance and the Tukey test with a 5% significance level. Results: Bio-C Repair had a greater filling ability than MTA HP (p < 0.05). IRM was similar to Bio-C and MTA HP (p > 0.05). MTA HP presented the largest volumetric change (p < 0.05), showing more volume loss than Bio-C and IRM, which were similar (p > 0.05). Conclusions: Bio-C Repair is a new endodontic material with excellent filling capacity and low volumetric change. The gypsum model proposed for evaluating filling ability and volumetric changes by micro-CT had appropriate and reproducible results. This model may enhance the physicochemical evaluation of premixed bioceramic materials, which need moisture for setting.

• 지질공학
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• 제24권2호
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• pp.179-189
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• 2014

We analyzed the three-dimensional distribution of micropores and internal structures in both fresh and weathered granite using micro-focus X-ray computed tomography (micro-CT). Results show that the pore radius in fresh granite is mostly in the range of $17-50{\mu}m$, the throat radius is in the range of $5-25{\mu}m$, and the coordination number (CN) of pores is less than 10. In contrast, the pore radius in weathered granite is mostly in the range of $20-80{\mu}m$, the throat radius is in the range of $8-30{\mu}m$, and the CN is less than 12. In general, a positive linear relationship exists between pore radius and CN. In addition, both the size and the density of pores increase with an increasing degree of rock weathering. The size of the throats that connect the pores also increases with an increasing degree of weathering, which induces fracture propagation in rocks. Micro-CT is a powerful and versatile approach for investigating the three-dimensional distributions of pores and fracture structures in rocks, and for quantitatively assessing the degree of pore connectivity.

• International Journal of Oral Biology
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• 제37권3호
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• pp.85-90
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• 2012

Periodontal disease induces an increased incidence of tooth loss, particularly in cases with an associated loss of alveolar bone and periodontal ligaments. In this study, alveolar bone loss was detected by micro-computed tomography (CT) following exposure to E. coli lipopolysaccharide (LPS) in a streptozotocin (STZ)-induced diabetic mouse model. A 10 mg/ml dosage of E. coli LPS was applied between the first, second and third molars of the mice three times a week for 10 weeks. The loss of periodontal ligaments and alveolar processes was then evaluated by micro-CT using two and three dimensional microstructure morphometric parameters. In the diabetic mice, E. coli LPS induced the destruction of periodontal ligaments and loss of alveolar process spaces. The distances between periodontal ligaments were significantly widened in the STZ-LPS group compared with the untreated STZ group. The 10 mg/ml exposure to E. coli LPS in the STZ mice also resulted in a significant decrease in the alveolar bone volume fraction. The results of our study suggest that alveolar bone loss can be readily detected by volumetric micro-CT analysis as an increase in the distance between periodontal ligaments and in the alveolar process length.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.647-648
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• 2006

The length of root canal has to be measured to cure root canal. Several apex locators were developed to measure the length of root canal. And they were verified by X-ray or micrometer method. But these methods do not consider the non-linear bends of pulp and have ${\pm}0.5mm$ error which is large to measure the length of root canal. The purpose of this study is the research of new method to measure the length of root canal and verifying the apex locator using Micro-CT. The length of root canal of 6 teeth were measured with the apex locator. When the apex locator reads 0.5, 0.6, 0.7, 0.5, 0.9, 1.0mm, the teeth with the file fixed were photographed. The average lengths of root canal of 6 teeth measured by Micro-CT were 0.488, 0.589, 0.680, 0.775, 0.897, 0.992mm.

• Restorative Dentistry and Endodontics
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• 제42권4호
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• pp.273-281
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• 2017

Objectives: The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (${\mu}CT$). Materials and Methods: Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF (n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using ${\mu}CT$. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test. Results: Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15-1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score (p < 0.05). Conclusions: The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.

• 한국정밀공학회지
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• 제27권4호
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• pp.95-101
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• 2010

The aim of this study was to detect longitudinal alterations on lumbar vertebral trabecular bone quality (microarchitecture and degree of mineralization) and bone mineral density (BMD) during pregnancy Virginal eighteen mice were used. Then, twelve mice were mated. Mice lumbar vertebrae were scanned before mate, at 7 days of pregnancy (early pregnancy, 6 mice) and immediately after delivery (late pregnancy, 6 mice) by using in-vivo micro-computed tomography Structural parameters, degree of mineralization and BMD were measured. During early pregnancy, there were no significant alterations on structural parameters, degree of mineralization and BMD. At late pregnancy, Tb.Th (11.8%) and BMD (12.7%) were significantly decreased and Tb.N (6.3%), Tb.Pf (43.0%) and BS/BV (15.1%) were significantly increased (p<0.05). Additionally, the lower degree of mineralization was increased, although, the higher degree of mineralization was decreased. These results indicated that the quality and BMD might be not affected during early pregnancy. At late pregnancy, however the bone quality and BMD were likely to be negatively affected.

• 대한소아치과학회지
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• 제31권3호
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• pp.495-500
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• 2004

치내치(dens invaginatus)는 치아 발생 과정 중 경조직이 석회화되기 전에 법랑질 상피가 함입되어 생기는 치아 기형이다. 치내치는 함입된 정도에 따라 다양한 형태학적 변이를 보이는데 이러한 기형은 미생물이 침입할 수 있는 통로가 될 수 있어 치수조직의 괴사와 치근단 농양 또는 치은 농양의 원인이 된다. 이러한 경우 근관의 복잡한 해부학적 형태 때문에 근관 치료가 매우 어렵다. 본 증례는 상악 좌측 측절치의 동통을 주소로 내원한 두 명의 환아들에 관한 것이다. 첫 번째 증례는 수산화 칼슘제재를 이용한 근관치료를 시행하여 양호한 결과를 얻었고 두 번째 증례는 치아를 발거하였다. 발거된 치아는 미세전산화 단층촬영을 이용하여 해부학적 형태를 살펴보았기에 보고하는 바이다.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.61-70
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• 2012

In this study, a simple post-reconstruction dual-energy computed tomography (CT) method is proposed. A dual-energy CT algorithm for monochromatic x-rays was adopted and applied to the dual-energy CT of polychromatic x-rays by assigning a representative mono-energy. The accuracy of algorithm implementation was tested with mathematical phantoms. To test the sensitivity of this algorithm to the inaccuracy of representative energy value in energy values, a simulation study was performed with mathematical phantom. To represent a polychromatic x-ray energy spectrum with a single-energy, mean energy and equivalent energy were used, and the results were compared. The feasibility of the proposed method was experimentally tested with two different micro-CTs and a test phantom made of polymethyl methacrylate (PMMA), water, and graphite. The dual-energy calculations were carried out with CT images of all possible energy pairs among 40, 50, 60, 70, and 80 kVp. The effective atomic number and the electron density values obtained from the proposed method were compared with theoretical values. The results showed that, except the errors in the effective atomic number of graphite, most of the errors were less than 10 % for both CT scanners, and for the combination of 60 kVp and 70 kVp, errors less than 6.0 % could be achieved with a Polaris 90 CT. The proposed method shows simplicity of calibration, demonstrating its practicality and feasibility for use with a general polychromatic CT.

• Restorative Dentistry and Endodontics
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• 제43권1호
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• pp.3.1-3.10
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• 2018

Objectives: The aim of this study was to compare root canal volume change and canal transportation by Vortex Blue (VB; Dentsply Tulsa Dental Specialties), ProTaper Next (PTN; Dentsply Maillefer), and ProTaper Universal (PTU; Dentsply Maillefer) nickel-titanium rotary files in curved root canals. Materials and Methods: Thirty canals with $20^{\circ}-45^{\circ}$ of curvature from extracted human molars were used. Root canal instrumentation was performed with VB, PTN, and PTU files up to #30.06, X3, and F3, respectively. Changes in root canal volume before and after the instrumentation, and the amount and direction of canal transportation at 1, 3, and 5 mm from the root apex were measured by using micro-computed tomography. Data of canal volume change were statistically analyzed using one-way analysis of variance and Tukey test, while data of amount and direction of transportation were analyzed using Kruskal-Wallis and Mann-Whitney U test. Results: There were no significant differences among 3 groups in terms of canal volume change (p > 0.05). For the amount of transportation, PTN showed significantly less transportation than PTU at 3 mm level (p = 0.005). VB files showed no significant difference in canal transportation at all 3 levels with either PTN or PTU files. Also, VB files showed unique inward transportation tendency in the apical area. Conclusions: Other than PTN produced less amount of transportation than PTU at 3 mm level, all 3 file systems showed similar level of canal volume change and transportation, and VB file system could prepare the curved canals without significant shaping errors.