• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.187-195
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• 2021

In order to assess the cell toxicity of 10 instruments made of polymers, the MTT assay which utilizes the L-929 cell was selected. Specimens were eluted at a temperature of 37℃ for 24 hours at a rate of 4g per 20mL, RPMI 1640, and then was positively and negatively contrasted with a control test solution, in accordance with the Notification No. 2020-12 Protocols of Medical Apparatus Biological Safety from the Ministry of Drug and Food Safety. As a result of 24 hours of incubation in 37℃, 5% CO₂ Incubator and assessment using an ELISA reader, the results of Intraoral camera indiciated a cellular viability of more than 70% at a 50% eluate. But, the Plastic impression tray, 3D printing tweezer, Impression disposable syringe, Dental floss holder, Hand implant scaler, Surgical retractor, Oral scanner tip, Dental mirror, and the Water pick tip all reported a cellular viability of more than 70% at a 100% eluate, which indicates that do not exhibit cytotoxicity, thus allowing it to be used in contact with the mucous membrane of the oral cavity.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.263-272
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• 2001

The aim of this study was to investigate the influence of four different light curing modes on the marginal leakage of Class V composite resin restoration. Eighty extracted human premolars were used. Wedge-shaped class Y cavities were prepared on the buccal surface of the tooth with high-speed diamond bur without bevel. The cavities were positioned half of the cavity above and half beyond the cemento-enamel junction. The depth, height, and width of the cavity were 2 mm, 3 mm and 2 mm respectively. The specimens were divided into 4 groups of 20 teeth each. All the specimen cavities were treated with Prime & Bond$^{R}$ NT dental adhesive system (Dentsply DeTrey GmbH, Germany) according to the manufacturer's instructions and cured for 10 seconds except group VI which were cured for 3 seconds. All the cavities were restored with resin composite Spectrum$^{TM}$ TPH A2 (Dentsply DeTrey GmbH, Germany) in a bulk. Resin composites were light-cured under 4 different modes. A regular intensity group (600 mW/${cm}^2$, group I) was irradiated for 30 s, a low intensity group (300 mW/${cm}^2$, group II) for 60 s and a ultra-high intensity group (1930 mW/${cm}^2$, group IV) for 3 s. A pulse-delay group (group III) was irradiated with 400 mW/${cm}^2$ for 2 s followed by 800 mW/${cm}^2$ for 10 s after 5 minutes delay. The Spectrum$^{TM}$ 800 (Dentsply DeTrey GmbH, Germany) light-curing units were used for groups I, II and III and Apollo 95E (DMD, U.S.A.) was used for group IV. The composite resin specimens were finished and polished immediately after light curing except group III which were finished and polished during delaying time. Specimens were stored in a physiologic saline solution at 37$^{\circ}C$ for 24 hours. After thermocycling (500$\times$, 5-55$^{\circ}C$), all teeth were covered with nail varnish up to 0.5 mm from the margins of the restorations, immersed in 37$^{\circ}C$, 2% methylene blue solution for 24 hours, and rinsed with tap water for 24 hours. After embedding in clear resin, the specimens were sectioned with a water-cooled diamond saw (Isomet$^{TM}$, Buehler Co., Lake Bluff, IL, U.S.A.) along the longitudinal axis of the tooth so as to pass the center of the restorations. The cut surfaces were examined under a stereomicroscope (SZ-PT Olympus, Japan) at ${\times}$25 magnification, and the images were captured with a CCD camera (GP-KR222, Panasonic, Japan) and stored in a computer with Studio Grabber program. Dye penetration depth at the restoration/dentin and the restoration/enamel interfaces was measured as a rate of the entire depth of the restoration using a software (Scion image, Scion Corp., U.S.A.) The data were analysed statistically using One-way ANOVA and Tukey's method. The results were as follows : 1. Pulse-Delay group did not show any significant difference in dye penetration rate from other groups at enamel and dentin margins (p>0.05) 2. At dentin margin, ultra-high intensity group showed significantly higher dye penetration rate than both regular intensity group and low intensity group (p<0.05). 3. At enamel margin, there were no statistically significant difference among four groups (p>0.05). 4. Dentin margin showed significantly higher dye penetration rate than enamel margin in all groups (p<0.05).

• The Korean Journal of Nuclear Medicine
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• v.25 no.2
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• pp.286-293
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• 1991

$^{123}I$, which is applied for the thyroid and other in vivo kinetic study, has a special role in life sciences. The 159 KeV $\gamma-ray$ from $^{123}I$ is almost ideally appropriate for the current imaging instrumentation. Its decay mode (electron capture) and short half-life (13.3 hr) reduced the burden of radiation dose to the patients, and its chemical property makes it easy to synthesize the labelling compounds. In this experiment, the production of $^{123}I$ via the nuclear reaction $^{124}Te(p,2n)^{123}I$ with 28 MeV protons was sutdied. $TeO_2$ is used as a target material, because it has good physical properties. The target was prepared with $TeO_2$ powder and was molten into a ellipsoidal cavity (a=14 mm, b=10 mm, $270.8mg/cm^2$ thick) of pure platinum. The irradiation was carried out in the external proton beam with incident energies range from 28 MeV to 22 MeV, and current was $30{\mu}A$. The loss of $TeO_2$ target was significantly reduced by using $4\pi-cooling$ system in irradiation. The dry distillation method was adopted for the separation of $^{123}I$ from irradiated target, and when it was kept 5 minutes at $780^{\circ}C$, its result was quantitative. The loss of the target material $(TeO_2)$ was below 0.2% for each production run and $^{123}I$ from the dry distillation apparatus was captured with 0.01 N NaOH in $Na^{123}I$ form, then the pH of the solution was adjusted to $7.5\sim9.0$ with HC1/NaOH. The $Na^{123}I$ solution was passed through $0.2{\mu}m$ membrane filter, and sterilized under high pressure and temperature for 30 minutes. The production of $^{123}I$ is acceptable for clinical application based on the quality of USP XXI.

• Journal of Embryo Transfer
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• v.25 no.1
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• pp.9-14
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• 2010

This study was conducted to find out the effects of artificial shrinkage (AS) on post-thaw development of bovine embryos. The blastocoelic cavity of blastocyst was punctured to remove its fluid contents and then incubated in the holding medium (HM) for 10 min. The punctured and non-punctured (control) blastocysts were equilibrated in vitrification solution 1 (VS1; TCM-199+20% FBS+10% EG) for 5 min and vitrification solution 2 (VS2; TCM199+20% FBS+35% EG+5% PVP+0.5 M Sucrose) for 1 min and vitrified by direct dropping into the liquid nitrogen. Vitrified blastocysts (punctured and control) were thawed and cultured in vitro (12 hr) for studying survival and hatching rates. The levels of shrinkage were measured by the volume of the blastocyst during equilibration in VS1 (at 1, 3 and 5 min of equilibration) and VS2 (at 30 and 60 sec of equilibration) that was considering the volume of non-punctured blastocyst in HM as 100%. The levels of shrinkage were higher in punctured group (62.4, 64.6, 64.3% at 1, 3 and 5 min in VS1; 50.6 and 52.7% at 30 and 60 sec in VS2) than control group (84.8, 86.6, 86.4% at 1, 3 and 5 min in VS1; 72.1 and 68.8% at 30 and 60 sec in VS2), but within each group the levels of shrinkage were similar. The survival (90.9%) and hatching (50.0%) rates of vitrified blastocysts at 12 hr post-thaw were higher in punctured group than that in control group (76.9% and 0.0% respectively). We confirmed that vitrification solutions (VS1 and VS2) have no toxic effect on the survival of blastocysts because the survival rates of blastocysts exposed to VS1 and VS2 for 24 hr were similar between punctured and control groups (94.3 vs. 96.0%; p>0.05). In conclusion, the preliminary data show that AS of blastocyst may improve survival and hatching rate after thawing.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.663-674
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• 2006

It is very important that analysis of textures in rock, the moving of hydrothermal solution along the structures, epithermal vein textures, mineralization and composition minerals to confirm the hydrothermal ore deposits and ore genesis. The purpose of this study is to confirm the gold mineralization and ore genesis through the moving of hydrothermal solution along the structure lines and epithermal vein textures by using Color-corescanner techniques. The three drilling hole cores of Sunshin Gold Mine in Haenam area in Jeonnam Province were into a digital image data. Digital image data of gold bearing epithermal vein textures were analyzed detaily by Color-corescanner. There are several epithermal vein textures, namely Comb texture, Cavity texture, Bladed texture, Zonal texture, Brecciated texture and Combined texture. Gold mineralization is dominated in vein type textures, but high grade gold are enbedded in brecciated texture. Ore genesis is epithermal gold deposit. This Color-corescanner techniques can cover the missing part of the examine with the naked eye, and can examine closely the situation of ore deposit development and genesis by detail checking the textures in rock, mineralization and so on.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.588-595
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• 1989

Log K, ${\Delta}$H and ${\Delta}$S for the complexation of $La^{3+},\;Ce^{3+}$ and $Eu^{3+}$with various multidentate ligand containing crown ether, diaza crown ether and diamine ether have been determined in methanol and acetonitril solutions at $25^{\circ}C$ by solution calorimetric titration method. The greater stability constant of $La^{3+}$-15C5 than those of 18C6 diaza [2.2] in methanol are discussed in terms of the size of metal ion and the ligand cavity and of metal ion solvation. The stabilities of $Ce^{3+}$ and $La^{3+}$ ion complexes with a various multidentate ligand in acetonitril are in the order of (diamine ether)<18C6<15C5$Ce^{3+}$, $La^{3+}$ and $Eu^{3+}$-diaza [2.2] complexes in acetonitril are increased with the following order: $Eu^{3+}$ < $La^{3+}$ < $Ce^{3+}$, that is increasing order of the optimum size and of the charge density of metal ion.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.615-630
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• 2002

Various long-term studies have shown that titanium implants as abutments for different types of prostheses have become a predictable adjunct in the treatment of partially or fully edentulous patients. The continuous exposure of dental implants to the oral cavity with all its possible contaminants creates a problem. A lack of attachment, together with or caused by bacterial insult, may lead to peri-implantitis and eventual implant failure. Removal of plaque and calculus deposits from dental titanium implants with procedures and instruments originally made for cleaning natural teeth or roots may cause major alterations of the delicate titanium oxide layer. Therefore, the ultimate goal of a cleaning procedure should be to remove the contaminants and restore the elemental composition of the surface oxide without changing the surface topography and harming the surrounding tissues. Among many chemical and mechanical procedure, air-powder abrasive have been known to be most effective for cleaning and detoxification of implant surface. Most of published studies show that the dental laser may be useful in the treatment of pen-implantitis. $CO_2$ laser and Soft Diode laser were reported to kill bacteria of implant surface. The purpose of this study was to obtain clinical guide by application these laser to implant surface by means of Non-contact Surface profilometer and X-ray photoelectron spectroscopy(XPS) with respect to surface roughness and atomic composition. Experimental rough pure titanium cylinder models were fabricated. All of them was air-powder abraded for 1 minute and they were named control group. And then, the $CO_2$ laser treatment under dry, hydrogen peroxide and wet condition or the Soft Diode laser treatment under Toluidine blue O solution condition was performed on the each of the control models. The results were as follows: 1. Mean Surface roughness(Ra) of all experimental group was decreased than that of control group. But it wasn't statistically significant. 2. XPS analysis showed that in the all experimental group, titanium level were decreased, when compared with control group. 3. XPS analysis showed that the level of oxygen in the experimental group 1, 3($CO_2$ laser treatment under dry and wet condition) and 4(Soft Diode laser was used under toluidine blue O solution) were decreased, when compared with control group. 4. XPS analysis showed that the atomic composition of experimental group 2($CO_2$ laser treatment under hydrogen peroxide) was to be closest to that of control group than the other experimental group. From the result of this study, this may be concluded. Following air-powder abrasive treatment, the $CO_2$ laser in safe d-pulse mode and the Soft Diode laser used with photosensitizer would not change rough titanium surface roughness. Especially, $CO_2$ laser treatment under hydrogen peroxide gave the best results from elemental points of view, and can be used safely to treat peri-implantitis.

• Applied Microscopy
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• v.31 no.2
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• pp.175-184
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• 2001

This study aims demonstrate the effect of chitosan, one of the natural chelator, on the ultrastructural changes in the mouse liver caused by $HgCl_2$. The experimental group was divided in two groups; group A and group B. The group A administrated $HgCl_2$ (5.0 mg/kg) to the oral. The group B treated with $HgCl_2$ (5.0 mg/kg) and chitosan (3%) solution, 2 times/day). Each group was observed 24, 48, 72 and 96 hours after treated $HgCl_2$ and chitosan. Histological changes of the livers were investigated by electron microscope. 1. Croup A Nuclear membrane was shrinked. The inner and outer membrane of the mitochondria were dilated. Destruction of lamellae of rough endoplasmic reticulum showed. Smooth endoplasmic reticulum showed over cytoplasm. 2. Group B Nuclear membrane was more rounded, The cristae of the mitochondria were almost normal shape and electron-density showed compacted. Dilation of inner cavity of rough endoplasmic reticulum showed at the pre-time but formed typical lamellae at the 48Hrs. Smooth endoplasmic reticulum showed over cytoplasm. Therefore, we concluded that chitosan has significantly protective effects in liver to harmful $HgCl_2$.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.184-193
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• 2016

Purpose: To evaluate marginal leakage of bulk fill flowable composite resin filling with different curing time by using microcomputed tomography technology. Materials and Methods: 30 previously extracted human molars were randomly divided into 6 groups based upon restorative system and different curing time. Class II cavities (vertical slot cavities) were prepared. An individual metallic matrix was used to build up the proximal wall. The SonicFill or SureFil SDR flow was inserted into the preparation by using 1 bulk increment, followed by light polymerization for different curing times. The different exposure times were 20, 40, and 60 seconds. All specimens were submitted to 5,000 thermal cycles for artificial aging. Micro-CT scanning was performed by using SkyScan 1272. One evaluator assessed microleakage of silver nitrated solution at the resin-dentin interface. The 3D image of each leakage around the restoration was reconstructed with CT-Analyser V.1.14.4. The leakage was analyzed with the Mann-Whitney test. Results: Significant differences were observed between the light curing times, but no significant differences were found between the bulk fill composite resins. Increasing in the photoactivation time resulted in greater microleakage in all the experimental groups. Those subjected to 60 seconds of light curing showed higher microleakage means than those exposed for 20 seconds and 40 seconds. Conclusion: Increasing the photoactivation time is factor that may increase marginal microlekage of the bulk fill composite resins. Further, micro-CT can nondestructively detect leakage around the resin composite restoration in three dimensions.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.118-124
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• 1995

The crystal structure of an iodine sorption complex of vacumm-dehydrated Ag+ and Ca2+ exchanged zeolite A(a=12.174(3)Å) has been determined at 21℃ by single-crystal X-ray diffraction techniques in the cubic space group Pm3m. The crystal was prepared by flow method for three days using exchange solution in solution in which mole ratio of AgNO3 and Ca(NO3)2 was 1:150 with total concentration of 0.05 M. The complex was prepared by dehydration at 360℃ and 2×10-6 Torr for 2 days, followed by exposure to about 14.3 Torr of iodine vaporat 80℃ for 24 hours. Full-matrix least-squares refinement converged to the final error indices of R1=0.082, R2=0.068 using 122 reflections for which I > 3σ(I). Two Ag+ ions, 1.1 Ag+ ions, and 4.45 Ca2+ ions per unit cell are located on three different three-fold axes associated with 6-ring oxygens. Two Ag+ ions per unit cell are in the large cavity, 1.399(4)Å from the (111) plane of three oxygens. Another 1.1 Ag+ ions are found at opposite sites. Six iodine molecules are sorbed per unit cell. Each I2 molecule approaches a framework oxide ion axially (O-I=3.43(2)Å, I-I=2.92Å, I-I-O;166.1(3)°), by a charge transfer complex interaction. Two Ag+ ions make a close approach to the iodine molecules (Ag-I ; 2.73(2)Å).