• Imaging Science in Dentistry
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• v.47 no.3
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• pp.165-174
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• 2017

Purpose: This study was performed to investigate the influence of object shape and distance from the center of the image on the volumetric accuracy of cone-beam computed tomography (CBCT) scans, according to different parameters of tube voltage and current. Materials and Methods: Four geometric objects(cylinder, cube, pyramid, and hexagon) with predefined dimensions were fabricated. The objects consisted of Teflon-perfluoroalkoxy embedded in a hydrocolloid matrix (Dupli-Coe-Loid TM; GC America Inc., Alsip, IL, USA), encased in an acrylic resin cylinder assembly. An Alphard Vega Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) was used to acquire CBCT images. OnDemand 3D (CyberMed Inc., Seoul, Korea) software was used for object segmentation and image analysis. The accuracy was expressed by the volume error (VE). The VE was calculated under 3 different exposure settings. The measured volumes of the objects were compared to the true volumes for statistical analysis. Results: The mean VE ranged from -4.47% to 2.35%. There was no significant relationship between an object's shape and the VE. A significant correlation was found between the distance of the object to the center of the image and the VE. Tube voltage affected the volume measurements and the VE, but tube current did not. Conclusion: The evaluated CBCT device provided satisfactory volume measurements. To assess volume measurements, it might be sufficient to use serial scans with a high resolution, but a low dose. This information may provide useful guidance for assessing volume measurements.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.45-50
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• 2013

Non-invasive technique CT, called automated computed tomography, is used to detect lesion of a patient when diagnosing human body. Information obtained from CT plays an important role in assembling 3 dimensional images. Recently, new equipment, operated by CT, is required which can be appliable to physical and biological research. In accordance to this quest, micro-CT is invented that produce more detail and concrete information. Images supplied by CT are even more detailed and concrete, so it contributes much to the development of biology and polymer material engineering field. However, there has been little reliable reports regarding measuring information of space dose distribution about exposure dose limit of users operating micro-CT. In addition, little reports regarding space dose distribution of exposure has been known about unwanted diffraction light produced by usage of micro-CT. The exterior of micro-CT is covered by lead, which is for removing exposure of diffraction light. Thus, even if it is good enough to prevent exposure of diffraction light, consistent management of equipment will be required as time goes by and equipment are getting old as well. We measured space dose distribution regarding exposure of diffraction light of users operating micro-CT directly. Therefore, we suggest that proper management should be necessary for users operating micro-CT not to be exposed by unwanted diffraction light.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.396-405
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• 2010

Purpose: This study was performed to find out the effects of the Er:YAG laser (Key Laser) & Er,Cr:YSGG laser (Water Laser) on inflammatory tissues. Materials and Methods: It was performed on about 20 g, 6 weeks male ICR mouses. They were grouped into the control (negative), the inflammation induced 'control'(positive), Er,Cr:YSGG laser exposured group after inducing inflammation, Er:YAG lasere exposured group after inducing inflammation each 15 mouses. The mouses were applicated 0.5% DNFB 1 cc on ear skin twice a day for 4 days until symptom expression. After laser exposure, ear tissues were extracted and defined gene expression by RT-PCR. Then, tissue staining, lymphocytes observation, electromicroscophic laboratory were carried out. Results: Interleukin-$1{\beta}$ was expressed much less in the A-laser exposed group. Interleukin-$1{\beta}$ & Tumor Necrosis Factor-${\alpha}$ were expressed 7 times lesser in the A-laser exposed group. The number of Lymphocytes related to inflammation was decreased rapidly in the A-laser exposed group in vivo. he number of cavity recovered normal was a little bigger in the A-laser exposed group after 5 days Conclusion: The expression of IL-$1{\beta}$ & TNF-${\alpha}$, hitologic change, observation with electron microscope shows that Erbium laser exposure causes lesser inflammation with A-laser rather than B-laser.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.314-320
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• 2013

With a prevalence rate of 0.01%, the presence of eruption disturbances of mandibular first molar has rarely been in populations. Eruption disturbances of permanent molars have been usually manifested as impaction, primary retention, and secondary retention. The treatments of eruption disturbances are carried out by: periodic observation; surgical exposure; forced eruption after surgical exposure; forced eruption with luxation; surgical repositioning; and extraction. This case report show successfully erupted mandibular first molars by various treatment methods on five patients diagnosed with impaction, primary retention, and secondary retention, respectively. Eruption disturbances of the mandibular first molar can be properly diagnosed with impaction, primary retention, and secondary retention by clinical and radiographic examination at normal eruption time of the mandibular first molar. The treatment should be done synthetically, considering eruption state of affected tooth, the relationship between the affected tooth and the adjacent or opposite tooth, the patient's age, treatment compliance, and economic state.

• Toxicological Research
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• v.31 no.4
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• pp.347-354
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• 2015

Excess manganese (Mn) is neurotoxic. Increased manganese stores in the brain are associated with a number of behavioral problems, including motor dysfunction, memory loss and psychiatric disorders. We previously showed that the transport and neurotoxicity of manganese after intranasal instillation of the metal are altered in Hfe-deficient mice, a mouse model of the iron overload disorder hereditary hemochromatosis (HH). However, it is not fully understood whether loss of Hfe function modifies Mn neurotoxicity after ingestion. To investigate the role of Hfe in oral Mn toxicity, we exposed Hfe-knockout ($Hfe^{-/-}$) and their control wild-type ($Hfe^{+/+}$) mice to $MnCl_2$ in drinking water (5 mg/mL) for 5 weeks. Motor coordination and spatial memory capacity were determined by the rotarod test and the Barnes maze test, respectively. Brain and liver metal levels were analyzed by inductively coupled plasma mass spectrometry. Compared with the water-drinking group, mice drinking Mn significantly increased Mn concentrations in the liver and brain of both genotypes. Mn exposure decreased iron levels in the liver, but not in the brain. Neither Mn nor Hfe deficiency altered tissue concentrations of copper or zinc. The rotarod test showed that Mn exposure decreased motor skills in $Hfe^{+/+}$ mice, but not in $Hfe^{-/-}$ mice (p = 0.023). In the Barns maze test, latency to find the target hole was not altered in Mn-exposed $Hfe^{+/+}$ compared with water-drinking $Hfe^{+/+}$ mice. However, Mn-exposed $Hfe^{-/-}$ mice spent more time to find the target hole than Mn-drinking $Hfe^{+/+}$ mice (p = 0.028). These data indicate that loss of Hfe function impairs spatial memory upon Mn exposure in drinking water. Our results suggest that individuals with hemochromatosis could be more vulnerable to memory deficits induced by Mn ingestion from our environment. The pathophysiological role of HFE in manganese neurotoxicity should be carefully examined in patients with HFE-associated hemochromatosis and other iron overload disorders.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.55-61
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• 2014

In this study, we evaluated the measurement of working environment, the amount of exposure, the hazards and risks of biphenyl, that was registered as 2A in IARC. Based on the exposure scenario, it was calculated that the exposure amounts are $1.0{\times}10^{-2}$, $4.2{\times}10^{-4}$, $7.0{\times}10^{-6}mg/m^3$, respectively, and the $RfC_{work}$ is 0.21, 2.13, 0.53 $0.31mg/m^3$ as carcinogenicity, target toxicity (oral), target toxicity (inhalation), developmental toxicity, respectively. According to these hazards evaluation and risk assessments, it was estimated that 0.57, 0.39 as carcinogenicity and non-carcinogenicity (developmental toxicity), respectively. It was also estimated relatively lower risks below 1. But since biphenyl is hazardous used much amounts, and could be exposed to workers directly, it was determined to require exposure monitoring to protect workers' health.

• Nutrition Research and Practice
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• v.8 no.1
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• pp.46-53
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• 2014

Inorganic arsenic (iAs) is a toxic metalloid found ubiquitously in the environment. In humans, exposure to iAs can result in toxicity and cause toxicological manifestations. Arsenic trioxide ($As_2O_3$) has been used in the treatment for acute promyelocytic leukemia. The kidney is the critical target organ of trivalent inorganic As ($iAs^{III}$) toxicity. We examine if oral administration of astaxanthin (AST) has protective effects on nephrotoxicity and oxidative stress induced by $As_2O_3$ exposure (via intraperitoneal injection) in rats. Markers of renal function, histopathological changes, $Na^+-K^+$ ATPase, sulfydryl, oxidative stress, and As accumulation in kidneys were evaluated as indicators of $As_2O_3$ exposure. AST showed a significant protective effect against $As_2O_3$-induced nephrotoxicity. These results suggest that the mechanisms of action, by which AST reduces nephrotoxicity, may include antioxidant protection against oxidative injury and reduction of As accumulation. These findings might be of therapeutic benefit in humans or animals suffering from exposure to $iAs^{III}$ from natural sources or cancer therapy.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.465-471
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• 2012

In this study, three dimensional X-ray dose distribution from dental X-ray generator system was measured by ALOKA PDM-117 dosimeter. The X-ray dose distribution will be change with XCP-DS FIT in oral shot, because the distance between X-ray generator and the dosimeter. The X-ray dose change affects on patient exposure and radiograph image quality. Therefore, it is important to obtain relation between the X-ray dose and the distance. The X-ray dose at the central position was decreased with increasing the distance. Furthermore, the dose at the edge of the X-ray flux was increased with increasing the distance. The increased dose affects on the patient radiation exposure. The present results will provide for good dental radiograph image and reducing radiation over-exposure on patient.

• The Journal of Dong Guk Oriental Medicine
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• v.7 no.2
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• pp.149-154
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• 1999

The effect of Yukilsunki-tang extracts on global cerebral ischemia were investigated in this study. The multiple parameters of global cerebral ischemia assessed in mice included the duration of KCN-induced(1.8mg/kg i.v.) coma, the survival time of KCN-induced(3.0mg/kg i.v.) coma, the survival time exposed to hypoxia induced by vacuum pump. In the case of global cerebral ischemia International Cancer Research mice were used and divided into two groups at random Group A, normal control, was treated after oral administration of normal saline. Group B, experimental control, was treated after oral administration of 13.2mg/20g of Yukilsunki-tang extracts. Each treatment was KCN-induced(1.8mg/kg i.v.) coma, KCN-induced(3.0mg/kg i.v.) coma and exposure to hypoxia induced by vacuum pump. The results were obtained as follows ; In global cerebral ischemia, Yukilsunki-tang extracts significantly prolonged the duration of KCN-induced(1.8mg/kg i.v.) coma, the survival time of KCN-induced(3.0mg/kg i.v.) coma and the survival time of exposure to hypoxia induced by vacuum pump in mice. Conclusion Yukisunki-tang extracts had a significant effect on Global cerebral ischemia.

• Journal of Preventive Medicine and Public Health
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• v.43 no.2
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• pp.131-137
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• 2010

Objectives: Bisphenol A diglycidyl ether (BADGE) is a liquid compound obtained by condensation of two molecules of epichlorohydrin with one molecule of bisphenol A. General and reproductive toxicity with BADGE has been reported higher than 1000 mg/kg/day. This study was performed to show the effects of acute exposure to BADGE below 1000 mg/kg/day on the testis in adult male rats. Methods: BADGE was administered by gastric lavage in a single dose of 500, 750, 1000, and 2000 mg/kg/day in 8-week old male SPF Sprague-Dawley rats. The right testis was processed for light microscopic analysis. The left testis was homogenized and spermatids were counted to determine the daily sperm production and daily abnormal sperm production. The sperm count, sperm motility, and incidence of abnormal sperm were estimated in the epididymis. In testicular sections, the seminiferous tubules were observed for qualitative changes. The progression of spermatogenesis was arbitrarily classified as full-matured, maturing, and immature. The specimen slide was observed at 3 points and 10 seminiferous tubules were evaluated at each point. Results: The male rats exposed to single oral dose of BADGE at 750, 1000, and 2000 mg/kg/day were significantly increased the number of immature and maturing sperm on the testis. There were no significant differences with respect to sperm head count, sperm motility, and sperm abnormality in the BADGE treatment groups. Conclusions: These results suggest that single oral exposure of BADGE 750 mg/kg/day can affect adult male testis development.