• Journal of the korean academy of Pediatric Dentistry
• /
• v.25 no.2
• /
• pp.400-420
• /
• 1998

We already know that it is very difficult to obtain an "isolated field" for direct bonding during the surgical exposure of unerupted teeth. The aim of this in-vitro study is to simulate the clinical situation of forced eruption and to evaluate the tensile strengths of preligatured button with several types of contamination which can happen during the surgical exposure of unerupted teeth. Four orthodontic direct bonding systems were used. ($Ortho-One^{TM}$, $Rely-a-Bond^{(R)}$, $Ortho-Two^{TM}$, Phase $II^{(R)}$) Each material was divided into four groups(n=20) : Group 1. (Control, no contamination), Group 2. (Rinse etching agent with saline instead of water), Group 3. (Blood contamination of etched surface for 30 seconds), Group 4. (Blood contamination of primed surface for 30 seconds) 320 bovine anterior permanent teeth were divided into the above mentioned 16 groups. Enamel surface was flattened and ground under water coolant. Pre-ligatured buttons were prepared to the same form. (Cut 0.25 ligature wire 10 cm in length. Twist the ligature wire 30 times clockwise. Mark the wire 15mm and 35mm points from button. Make a loop sticking two points together and twist the loop 6 times counterclockwise.) The bonded specimens were stored at $37^{\circ}C$ saline solution for 3 days. Then the tensile strength of each sample was measured with Instron universal testing machine, crosshead speed of 0.5mm/min. The following results were obtained: 1. As compared to control groups (Group 1) of each material, Rely-a-Bond had a significantly lower mean tensile strengths than other material. (p<0.01) 2. In Group 2. of Ortho-One and Rely-a-Bond, the mean tensile strengths decreased about 7.7% and 11.1%, respectively with statistical significances. (p<0.05) 3. In Group 2. of Ortho-Two and Phase II, the mean tensile strengths did not decrease. 4. In Group 3. of Ortho-One, Rely-a-Bond, Ortho-Two, and Phase II, the mean tensile strengths decreased about 60.8%, 56.1%, 60.2%, and 46.0%, respectively with statistical significances. (p<0.01) 5. In Group 4. of Ortho-One and Rely-a-Bond, the mean tensile strengths did not decrease. 6. In Group 4. of Ortho-Two and Phase II, the mean tensile strengths were decreased about 20.95% and 22.28%, respectively with statistical significances. (p<0.01) There were formations of a hump shaped mass from bonding resin under blood contamination which disturbed direct bonding procedure. According to Reynolds, the proper bond strength for clinical manipulation should be at least 45N or about 4.5Kg.F. According to these results, it can be concluded that Ortho-One could be used during surgical exposure of unerupted teeth. In any case, blood contamination of the etched surface should be avoided, but the blood contamination of primed surface of Ortho-One may not decrease bond strength. Just 'blowing-out' is enough to remove blood from primed surface of Ortho-One. You can verify the clean surface of the primer of Ortho-One after blowing out the blood contamination.

• Journal of dental hygiene science
• /
• v.7 no.3
• /
• pp.153-159
• /
• 2007

To investigate requirements for the process of credit bank system in life-long education institutions attached to colleges, this research was conducted with seniors at the departments of dental hygiene and dental laboratory technology, in the health line of the specific College from March 26 to April 15, 2007, followed by analysis using an SPSS/WIN 12.0 program, obtaining the following results. 1. 89.7% of the respondents had a plan to take a bachelor's degree and 56.1% of whom had such a plan for the purpose of personal development (p<0.05). 2. 73.5% of the respondents preferred the credit bank system in a lifelong education institution attached to a college to take a bachelor's degree. 3. 34.8% presented the greatest advantage of taking a bachelor's degree through the credit bank system that they could take a degree in a short period of time while 33.8% presented the most serious disadvantage that they might low social recognition. 4. As for requirements for the process of operating the credit bank system, 80.3% regarded required subjects for the major as appropriate basic ones. 79.9% regarded it as proper that filling more than 20 credits made it possible to take a degree. 5. As directions for improving the system, it was found that the students was thinking that strict academic record management is needed, and the degrees from the system must be recognized equally to those in regular colleges, social awareness in those degrees should be enhanced, and also credits assigned to cultural subjects should be reduced, and the limitation in the number of credits being able to be obtained in one center should be removed.

• Journal of dental hygiene science
• /
• v.8 no.4
• /
• pp.267-274
• /
• 2008

The purpose of this study was to examine the use of dentifrice among children in a bid to provide information on dentifrice including its function to children's parents, the major consumers of dentifrice for child. And it's additionally meant to offer useful information on the production of toothpaste for kid. The subjects in this study were parents with children, who dwelled in Seoul and Gyeonggi province. After a self-administered survey was conducted for about three months from May to July 2007 to gather data on their use of dentifrice for child, a comparative analysis was implemented. The findings of the study were as follows: 1. Concerning the state of the use of their children's dentifrice, the largest number of the children(58.1%) started to use toothpaste at the age of one or down, and the most common first toothpaste they used was dentifrice for preschooler(86.8%). As for whether to use fluoride-containing toothpaste, the largest group of the parents(58.1%) gave an affirmative answer. Regarding the form of the toothpaste in use, the majority of their children used toothpaste of cream type(86.2%). The greatest group of the children used the amount of toothpaste that was as large as the three-tenths or four-tenths of the bristles(35.9%). 2. As for the state of the use of dentifrice for kid, the greatest group used that kind of toothpaste(81.4%). In the event of those who didn't use it, the last time when their children used toothpaste for kid was when they were at the western age of 3(33.9%) and 4(33.9%). Concerning the reason why they replaced toothpaste for kid with one for adult, the largest group of the parents did that on their own judgment(58.1%). As to the right time for replacing toothpaste for kid by one for adult, the greatest group considered it advisable for children to start using toothpaste for adult at the western age of 4 or 5(43.2%). 3. In relation to the state of the purchase of toothpaste for their children, the largest group was under the moderate influence of the children when they bought it(45.2%). The greatest group attached importance to the ingredients of toothpaste(41.6%), and the most preferred ingredient was fluoride(56.3%). 53.0 percent took consideration on the content of ingredients or the instructions. 4. In regard to priorities for the choice of toothpaste for their children, they gave top priority to brand(16.7%), followed by quality(14.6%) and ingredients(13.5%). The age of the parents made a statistically significant difference to the children's age when they started using toothpaste, and how they started to do that and whether they used fluoride-containing toothpaste were statistically significantly different according to that as well(p < 0.01). In regard to the impact of the occupation of the parents, the use of fluoride-containing toothpaste was more common among the stay-at-home mothers(p < 0.01).

• Journal of Veterinary Clinics
• /
• v.27 no.5
• /
• pp.533-539
• /
• 2010

Stem cell-based therapy is under intensive investigation to treat acute renal failure (ARF). The purpose of this study was to evaluate available ARF models, and suggest a model appropriate to therapeutic evaluation of the stem cells in preclinical approach by determining the optimum concentration of nephrotoxic agents and duration of ischemia induction. Three different types of available acute kidney injury (AKI) animal models were analyzed using rats: Cisplatin (saline, 5 and 7.5 mg/kg, IP) or glycerol (saline, 8 and 10 ml/kg, IM)-induced nephrotoxicity as toxic models and ischemia-induced (sham, 35 and 45 minutes) nephropathy as an ischemic model. The relevance and applicability to investigate especially the regenerative ability of stem cells were evaluated regarding morphology, renal function and survival at this time point. In the point of renal function, 10 ml glycerol/kg and 7.5 mg cisplatin/kg model in toxic models and 45 min model in ischemia models showed significant decrease for the longer observation time compared to 8 ml glycerol/kg, 5 mg cisplatin/kg and the 35 min ischemia models, respectively. All groups were observed no mortality except 45 min-ischemia model with 50% survival. Histological significant alterations including cast formation in the tubular lumen, tubular necrosis and apoptosis were revealed on the second day in either ischemiaor glycerol-induced models, and on day 5 in cisplatin-induced models. The results indicate that ischemia 35 min-, cisplatin 7.5 mg/kg- and glycerol 10 ml/kg-induced AKI would be ideal animal models to monitor a outcome parameter related to the therapeutic effects on renal function with noninvasive techniques in the same animal at multiple time points. Our findings also suggest that the best time points for the functional or histological interpretation of renal will be on day 2 in both glycerol- and ischemia-induced AKI models and on day 5 in cisplatin-induced AKI.

• Radiation Oncology Journal
• /
• v.16 no.3
• /
• pp.325-335
• /
• 1998

Purpose : Since the mid cranial fossa is composed of various thickness of bone, the tissue inhomogeneity caused by bone would produce dose attenuation in cobalt-60 gamma knife irradiation. The correction factor for bone attenuation of cobalt-60 which is used for gamma knife source is -3.5$\%$. More importantly, nearly all the radiosurgery treatment planning systems assume a treatment volume of unit density: any perturbation due to tissue inhomogeneity is neglected, This study was performed to confirm the bone attenuation in mid cranial fossa using gamma knife. Materials and Methods : Computed tomography was performed after Leksell stereotactic frame had been liked to the Alderson Rando Phantom (human phantom) skull area. Kodak X-omat V film was inserted into two sites of pituitary adenoma point and acoustic neurinoma point, and irradiated by gamma knife with 14mm and 18mm collimator. An automatic scanning densitometer with a 1mm aperture is used to measure the dose profile along the x and y axis. Results : Isodose curve constriction in mid cranial fossa is observed with various ranges. Pituitary tumor point is greater than acoustic neurinoma point (0.2-3.0 mm vs 0.1-1.3 mm) and generally 14 mm collimator is greater than 18mm collimator (0.4-3.0 mm vs. 0.2-2.2 mm) Even though the isodose constriction is found, constriction of 50$\%$ isodose curve which is used for treatment reference line does not exceed 1 mm. This range is too small to influence the treatment planning and treatment results. Conclusion : Radiosurgery planning system of gamma knife does not show significant error to be corrected without consideration of bone attenuation.

• Restorative Dentistry and Endodontics
• /
• v.30 no.5
• /
• pp.423-430
• /
• 2005

Ameloblasts are responsible for the formation and maintenance of enamel which is an epithelially derived protective covering for teeth. Ameloblast differentiation is controlled by sequential epithelial-mesenchymal interactions. However, little is known about the differentiation and maturation mechanisms. OD314 was firstly identified from odontoblasts by subtraction between odontoblast/pulp cells and osteoblast/dental papilla cells, even though OD314 protein was also expressed in ameloblast during tooth formation. In this study, to better understand the biological function of OD314 during amelogenesis, we examined expression of the OD314 mRNA and protein in various stages of ameloblast differentiation using in-situ hybridization and immunohistochemistry. The results were as follows : 1. The ameloblast showed 4 main morphological and functional stages referred to as the presecretory, secretory, smooth-ended, and ruffle-ended. 2. OD314 mRNA was expressed in secretory ameloblast and increased according to the maturation of the cells. 3. OD314 protein was not expressed in presecretory ameloblast but expressed in secretory ameloblast and maturative ameloblast. OD314 protein was distributed in entire cytoplasm of secretory ameloblast. However, OD314 was localized at the proxiamal and distal portion of the cytoplasm of smooth-ended and ruffle-ended ameloblast. These results suggest that OD314 may play important roles in the ameloblast differentiation and maturation.

• Restorative Dentistry and Endodontics
• /
• v.31 no.6
• /
• pp.437-444
• /
• 2006

This study was aimed to elucidate the biological function of OD314 (Apin protein), which is related to ameloblast differentiation and amelogenesis. Apin protein, calcifying epithelial odontogenic (pindborg) tumors (CEOTs)-associated amyloid, were isolated from CEOTs, and has similar nucleotide sequences to OD314. We examined expression of the OD314 mRNA using in-situ hybridization during tooth development in mice. Expression of OD314 and several enamel matrix proteins were examined in the cultured ameloblast cell line up to 28 days by reverse transcription-polymerase chain reaction (RT-PCR) amplification. After inactivation and over-expression of the OD314 gene in ameloblast cell lines using U6 vectordriven RNA interference and CMV-OD314 construct, RT-PCR were performed to evaluate the effect of the OD314 during amelogenesis. The results were as follows: 1. In in-situ hybridization, OD314 mRNAs were more strongly expressed in ameloblast than odontoblast. 2. When ameloblast cells were cultured in the diffcrentiation and mineralization medium for 28 days, the tuftelin mRNA expression was maintained from the beginning to day 14, and then gradually decreased to day 28. The expressions of amelogenin and enamelin were gradually decreased according to the ameloblast differentiation. 3. Inactivation of OD314 by U6-OD314 siRNA construct down-regulated the expression of OD314, MMP-20, and tuftelin, whereas over-expression of OD314 by CMV-OD314 construct up-regulated the expression of OD314 and MMP-20 without change in tuftelin. These results suggest that OD314 is considered as an ameloblast-enriched gene and may play the important roles in ameloblast differentiation and mineralization.

• Journal of Korean Society of Forest Science
• /
• v.23 no.1
• /
• pp.29-33
• /
• 1974

U-Reuk, a laureate musician in the days of King Jin-Heung, Silla Dynasty, built the Eui Rim Reservoir about 1,400 years ago. This was one of the oldest man-made reservoir. The embankment of the reservoir collapsed by the clumsy artificial drainage on August 19, 1972 when the heavy rainfall of 462 mm/day caused a dangerous overflow of the reservoir. The result of the study on the mystic ancient embankment techniques are as follows: 1. Sandy loam derived from the weathering of granite which is the most widely distributed rock type in the area, was used in the embankment. Large size logs (embankment core) of 30-50 cm in diameter were buried lengthwise along the embankment. 2. The six stocks of Pinus densiflora, 3 stocks of Quercus acutissima, 1 stock of Quercus variabilis and 1 stock of Popolus maximowiczii, altogether 11 stocks are identified. Forest types in the nearby area during the days of the reservoir construction seem to be includde a considerable number of Pinus densiflora, Quercus and Populus species. 3. The angle of repose of the earth materials is taken into account during the embankment. On top of the embankment double layers of clay (20-30 cm indepth) were spread and consolidated. Layer of litter of 20-40 cm in deep covered on the clay layer of the embankment completely, and another layer of clay was consolidated over the litter. Finally, a layer of stones of 10-30 cm in diameter and clay (yellow soil layer) toped the embankment. 4. At the lower part of the embankment clay layer was thicker and became thinner as it goes upwards. At every layer, soil was consolidated and burned. When embankment was completed, it was covered evenly with heavy clay, and finally it was topped with general soil. 5. The heavy clay layer on the inner slope of the embankment showed gray phenomena and litter remained raw humus layer. The clay layer functioned as rubber in the water, and raw humus layer prevented water from seepages. Thus, the embankment was solidly built in this way. 6. The ancient embankment techniques used soils conveyed from nearby area taking the angle of repose into account. Once embankment was completed, clay and litter layers were added to have a plasticity and to withstand the water pressure. 7. It is an excellent technique that the reservoir was constructed with least labor for maximum effects while the recent embankment techniques requires a large amount of labor.

• Korean journal of applied entomology
• /
• v.54 no.4
• /
• pp.401-407
• /
• 2015

This study describes the development of a method for monitoring Aphis gossypii in greenhouse cucumber fields that was used during 2013 and 2014. The dispersion pattern of A. gossypii was determined by commonly used methods: Taylor's power law (TPL) and Iwao's patchiness regression (IPR). The sample unit was determined by linear regression analysis between mean density of sample unit versus whole plant. The optimum sample unit for different plant growth stages was two leaves (median and the lowest + 1 leaf) when the total number of leaves was less than nine, and three leaves (4th, 7th from canopy, and the lowest +1 leaf) when the total number of leaves was greater than nine. A. gossypii showed an aggregated distribution pattern, as the slopes of both TPL and IPR lines were greater than 1. TPL provided a better description of the mean-variance relationship than did IPR. The slopes and intercepts of TPL and IPR from leaf samples did not differ between the surveyed years. Fixed precision levels (D) for a sequential sampling plan were developed using Green's and Kuno's equations based on the number of aphid in a leaf sample. Green's method was more efficient than Kuno's to stop sampling. The number of samples needed to estimate the density of A. gossypii increased at higher D levels and lower mean densities. The cumulative number of aphids needed to stop sampling increased at higher D levels and with fewer plants sampled. Thus to estimate 10 aphids per leaf, 13 plants needed to be sampled, and the cumulative number of aphids to stop sampling was 131.

• Journal of dental hygiene science
• /
• v.9 no.4
• /
• pp.435-441
• /
• 2009

The purpose of this study was to examine the use of dentifrice among preschoolers in an attempt to provide consumers with the right information on the choice of dentifrice and toothbrush for different age groups of children. The subjects in this study were parents who raised preschoolers in Seoul and Gyeonggi Province. A self-administered survey was conducted over approximately three months from May to July 2007 to find out the state of their children's use of dentifrice. After the collected data were analyzed, the following findings were given: The greatest group (51.5%) needed parental help with toothbrushing. The biggest group of the patients (35.6%) considered it necessary for children at the age of 6 and 7 to brush their teeth with the help of their parents. As to dentifrice squeezing and parental outlook on that, the biggest group of the parents (49.4%) replied their children squeezed the dentifrice for themselves, and the greatest group (42.2%) thought that children needed parental help with dentifrice squeezing by the age of five. Regarding dentifrice swallowing and parental perception of it, the biggest group (61.9%) saw their children swallowing the dentifrice, and the greatest group (73.7%) believed that children must not swallow the dentifrice. The biggest group of those who found it okay for children to swallow the dentifrice (62.5%) thought that it would be no problem to swallow the dentifrice for child. Concerning the use of toothbrushes, the biggest group (96.7%) had their children use toothbrushes for child. The above-mentioned findings of the study showed that the children who are at the age of 3 or down should use non-fluoride containing dentifrice or just a small amount of fluoride that is as equal as the size of a pea. Children must brush their teeth under the guidance of their parents, and sustained education should be provided about that.