• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.177-197
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• 1995

The endodontically treated tooth is generally restored with post & core, owing to the brittleness and the loss of large amount of tooth structure. Although there have been lots of studies about the endodontically treated teeth, the three-dimensional quantitative studies about the strees distribution of them are in rare cases. In this study, it was assumed that the coronal portion of the upper incisou had severely damaged. After the root canal therapy it was post cored, and restored with PFM crown, for this experiment nine types of model were constructed : 1); long, 2); medium, 3); short gold post for the roots supported with a narmal alveolar bone, 4); long, 5); medium, 6); short gold post for the roots supported with an alveolar bone resorbed to its 1/3 of root length, 7); long, 8); medium, 9); short base metal post for the roots supported with an alveolar bone resorbed to its 1/3 of root length. Force was applied from two directions. One was functional maximum bite force(300N) applied to the spot just lingual to the incisal edge with the angle of 45 degrees to the long axis of the tooth, and the other one was horizontal force(300N) applied to the labial surface. The results analyzed with three-dimensional finite element method were as follows : 1. Stress was concentrated on the middle portion of the labial side dentin of the root and the lingual portion of the apical dentin of the root. Stress in the post showed maximum value at 2 mm above the post apex. 2. In case of the long post and base metal post, strees was concentrated on the apex of the root and the post. 3. In case of the longer post, the displacement on the post-cement interface was lessened. The gold post was more displaceable than the base metal post. 4. In case of the alveolar bone resorption, stress concentrated on the root and the post and displacement on the post-cement interface were increased.

• The Journal of the Korean dental association
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• v.10 no.3
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• pp.149-153
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• 1972

The apical foramen is not always found on the very tip of the root. The apical foramen may make its exit on the mesial, distal, labial or lingual side of a root slightly short of the root apex rather than at the root apex itself. The author collected 43 upper first molars and 84 lower first molars as a samples. Apical foramens were carefully checked and examined these location on each tip. (table 1) 1. About 33% to 49% of upper cases were found on extreme tip of roots and the remaining cases were on the distal side or mesial side. 2. Except distal simple canal of lower molars, approximately 40% to 50% were located on the very tip of the root. The remaining cases were on distal or mesial surface. 3. On lower distal simple canal, about 51% of cases made its exit on distal side. The remaining cases located on the tip end or mesial side.

• The Journal of the Korean dental association
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• v.54 no.8
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• pp.658-665
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• 2016

Treatment of immature permanent teeth with irreversibly damaged pulp has been challenging in dental practice because of the lack of apical constriction, thin dentinal walls, and short roots. This may lead to the extrusion of filling materials, and fracture of the root due to its more fragile feature during shaping of the root canal. Apexification with calcium hydroxide or MTA is one of the treatment options for these cases. Although favorable results of apexification have been reported, these treatment procedures do not guarantee the increase of root length and/or width even after a long term period. Thus, treated teeth are still prone to fractures. Recently, pulp revascularization has been proposed as an alternative treatment for immature teeth with necrotic pulp and periapical pathosis. Pulp revascularization allows the stimulation of the apical development and the root maturation. There have been many treatment protocols using various materials such as antibiotics and calcium hydroxide medicament. In this case report, literature review about pulp revascularization and two related cases are presented.

• The Korean Journal of Physiology
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• v.30 no.1
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• pp.117-124
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• 1996

This study evaluated the hypothesis that motoneuron collaterals modulate the excitability of ventral spinocerebellar tract neurons. In acute cats, 128 ventral cerebellar tract cells were studied extracellularly to determine the effects of ventral root stimuli. The majority of the cells responded to ventral root stimulation with either short or long latency increases in spike discharge. In many cells with sufficient spontaneous activity ventral root stimulation also evoked a long lasting reduction in activity. In preparations with the dorsal root ganglion removed VSCT neurons had similar response properties. In some cells contralateral ventral root stimulation also evoked excitatory responses. These findings indicate the VSCT can provide the cerebellum with information regarding activity in the final output neurons of the motor system, the alpha motoneurons.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.2
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• pp.101-106
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• 2007

During mulberry cultivation, root disease complex caused by the association of root knot nematode (Meloidogyne incognita) with root rot pathogens like Fusarium solani and Botryodiplodia theobromae poses serious loss in leaf production. Therefore, an attempt was made to assess the efficacy of eight pesticides (Metayalaxyl+Mancozeb, Thiophanate methyl, Mancozeb, Bitertanol, Phenomiphos, Phorate, Thionazin & Carbofuran) and two growth hormones (Salicylic acid and Indole 3 acetic acid) at 0.1 and 0.2% concentrations under in vitro conditions against nematode (hatching of eggs and mortality of larvae) and root rot pathogens (poisoned food technique) for short listing the treatments to develop an IDM strategy. Results revealed that among the pesticides and growth hormones, Carbofuran followed by Salicylic acid were found to be effective at 0.2% concentration against both nematode and pathogenic fungi. Both the chemicals inhibited the hatching of nematode eggs by 83.5-78.9% and 80-76% larval mortality over the control and reduced the mycelial growth of both the pathogenic fungi to an extent of 75.5-77.8%. Though Mancozeb inhibited both the pathogenic fungi strongly (77-80%), it did not show any effectiveness against nematode. The rest of the chemicals were found either moderately or poorly effective in reducing the growth of pathogenic fungi, hatching of nematode eggs and enhancing the mortality of larvae. The two effective chemicals viz., Carbofuran and Salicylic acid, which rated as strong inhibitors against both nematode and pathogenic fungi, can be exploited in developing an IDM package as one of the component for better management of root disease complex in mulberry.

• Molecules and Cells
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• v.39 no.7
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• pp.524-529
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• 2016

Controlling the production of diverse cell/tissue types is essential for the development of multicellular organisms such as animals and plants. The Arabidopsis thaliana root, which contains distinct cells/tissues along longitudinal and radial axes, has served as an elegant model to investigate how genetic programs and environmental signals interact to produce different cell/tissue types. In the root, a series of asymmetric cell divisions (ACDs) give rise to three ground tissue layers at maturity (endodermis, middle cortex, and cortex). Because the middle cortex is formed by a periclinal (parallel to the axis) ACD of the endodermis around 7 to 14 days post-germination, middle cortex formation is used as a parameter to assess maturation of the root ground tissue. Molecular, genetic, and physiological studies have revealed that the control of the timing and extent of middle cortex formation during root maturation relies on the interaction of plant hormones and transcription factors. In particular, abscisic acid and gibberellin act synergistically to regulate the timing and extent of middle cortex formation, unlike their typical antagonism. The SHORT-ROOT, SCARECROW, SCARECROW-LIKE 3, and DELLA transcription factors, all of which belong to the plant-specific GRAS family, play key roles in the regulation of middle cortex formation. Recently, two additional transcription factors, SEUSS and GA- AND ABA-RESPONSIVE ZINC FINGER, have also been characterized during ground tissue maturation. In this review, we provide a detailed account of the regulatory networks that control the timing and extent of middle cortex formation during post-embryonic root development.

• Korean Journal of Plant Resources
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• v.35 no.6
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• pp.770-777
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• 2022

The main objective of this study was to identify the most appropriate condition for root formation of in vitro micropropagated pear (Pyrus spp.) plants. In vitro propagation was induced on Murashige and Skoog (MS) medium with 2.0 mg/L of N6-benzyladenine (BA) and 0.2 mg/L of Indole-3-butyric acid (IBA) medium. The short pre-treatment of explants with a high concentration (1 mg/L) of NAA and IBA (R0 medium) in dark for three days, followed by transfer to five different media (R1 to R5) resulted in good rooting responses in the pear 'Oharabani (P. pyrifolia × P. communis)' genotype. For the rooting experiments, the highest rooting percentage (83.3 ± 8.3%), average root length (3.6 ± 1.9 mm), total root number (31 ± 4.0), and average root number per plant (2.6 ± 2.1) were obtained on half strength (1/2) of MS medium supplemented with 30 g/L sucrose without hormones and activated charcoal (AC) (R1 medium). The highest rooting percentage was obtained at 83.3% from explants on R1 and R3 media. The rooting procedure described in this study resulted in good root formation and significantly shorting the root induction time to within 14 days of culture. Further studies are underway to test the suitability of the protocol developed in this study for other pear genotypes.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.399-402
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• 1997

It is important to find a accurate root canal length or successful endodontic therapy. By X-ray method takes a long time and difficult in a curved canal. After developed electronic apex locator has allowed to measure the root canal length with easy, in a short time also in a curved canal. But most electronic apex locators have the disadvantage which is too short reading or sometimes the measurement itself becomes impossible if there are electrolytes in the canal. To overcome this drawback, impedance ratio method has been developed. In this study, we have developed frequency dependent electronic apex locator to minimize the interference of electrolytes. And based on that also some error in clinic use, we added the other method. Difference of two signals which are used in calculation of impedance ratio was can be represent the status of root canal fluid. As a result, using impedance ratio method and auto-calibration by voltage difference method can reduce the measurement error.

• Journal of Periodontal and Implant Science
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• v.25 no.2
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• pp.290-300
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• 1995

Tooth mobility is one of the most important clinical parameters in examination, diagnosis, prognosis and treatment planning procedure. In order to determine the differences of tooth mobility according to radiographical bone level, clinical root length, clinical crown/root ratio, and bleeding on probing, 90 male adults with periodontal disease and 10 male adults with periodontal health($25{\sim}45$ years old) were selected through clinical examinations including occlusal relationship, probing depth, attachment level, and bleeding on probing. On the mandibular anterior teeth, standard periapical radiographs were taken, and tooth mobility was measured by Periotest(Siemens Co., Germany). The radiographic bone level of individual tooth was evaluated as coronal 1/3, middle 1/3, and apical 1/3 to anatomical root length, and clinical crown length from incisal edge to bone level and clinical root length from bone level to root apex were measured with Boley gauge, and subsquently clinical crown/root ratio was calculated. The difference of tooth mobility(Periotest value) according to radiographical bone level, clinical root length, clinical crown/root ratio, and bleeding on probing was statistically analyzed by unpaired Student t-test. Tooth mobility was significantly higher in bleeding group than non-bleeding group on probing in the teeth radiographic bone level of middle 1/3, with clinical root length longer than 6mm, and with clinical crown/root ratio over 0.3(p<0.01). But there was no statistical difference in tooth mobility between bleeding group and non-bleeding group on probing in the teeth with radiographic bone level of apical 1/3, with short clinical root length less than 5mm, and with clinical crown/root ratio under 0.2(p>0.05). The results note that the tooth mobility depends on clinical root length, clinical crown/root ratio and gingival inflammation, and in the teeth with relatively good alveolar bone support gingival inflammation is one of the most important factors that affect tooth mobility.

• Journal of Biosystems Engineering
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• v.22 no.1
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• pp.11-20
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• 1997

Thin layer drying tests of short gain rough rice were conducted in an experimental dryer equiped with air conditioning unit. The drying tests were performed in triplicate at three air temperatures of $35^circ$, $45^circ$, $55^circ$, and three relative humidities of 40%, 55%, 70%, respectively. Previously published thin layer equations were reviewed and four different models widely used as thin layer drying equations for cereal grains were selected. The selected four models were Pages, simplified diffusion, Lewis's and Thompson's models. Experimental data were fitted to these equations using stepwise multiple regression analysis. The experimental constants involved in tow equations were represented as a function of temperature and relative humidity of drying air. The results of comparing coefficients of determination and root mean square errors of miosture ratio for low equations showed that Page's and Thompsons models were found to fit adequately to all drying test data with coefficient of determination of 0.99 or better and root mean square error of moisture ratio of 0.025.