• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.4
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• pp.368-376
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• 2020

The primary maxillary second molars usually have three roots. However, an additional root located mesiopalatally is occasionally observed. This study aimed to determine the relationship between a mesiopalatal root of primary maxillary second molars and an abnormal eruption pattern of maxillary second premolars. The study was performed on cone beam computed tomography images taken from 916 children who visited the Dental Hospital of Kyung Hee University from 2010 to 2018. 744 serial cross-sectional cone beam computed tomography images were evaluated. The overall incidence of the mesiopalatal root of primary maxillary second molars was 3.2% (n = 24) and the abnormal eruption pattern of maxillary second premolars was 19.2% (n = 143). Especially, patients with the mesiopalatal root of primary maxillary second molars were significantly more likely to have the abnormal eruption pattern on maxillary second premolars (p = 0.000). The odds of the abnormal eruption pattern of maxillary second premolars with the mesiopalatal root of primary maxillary second molars was about 13 times higher than those without. The eruption pattern of the permanent successor should be carefully observed and treated if the mesiopalatal root of primary maxillary second molar is existent.

• Journal of Life Science
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• v.25 no.1
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• pp.37-43
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• 2015

We have investigated the effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), indole-3-acetic acid (IAA) and methyl jasmonate (MeJA) on the development of aerenchyma in the primary root of maize (Zea mays). Because plant hormones affected the longitudinal organization of the primary root, we need an indicator to direct the positions for comparison between control and hormone-treated roots. Therefore, the zones of the maize primary root were categorized as PR25, PR50 and PR75, where each value indicates the relative position between the root tip (PR0) and the base (PR100). Aerenchyma was not observed at PR25 and PR50 and rarely found at PR75 in the cortex of control roots. The aerenchymal area at PR75 increased in the presence of the ethylene precursor ACC or a natural auxin IAA. On the other hand, MeJA differentially acted on non-submerged and submerged roots. Exogenously applied MeJA suppressed the aerenchyma formation in non-submerged roots. When the primary root was submerged, aerenchymal area expanded prominently. The submergence-induced aerenchyma formation was amplified with MeJA. Lateral root primordia have been known to inhibit aerenchymal death of surrounding cells. All the three hormones stimulating aerenchyma formation as described above did not restore the inhibition caused by lateral root primordia, suggesting that the inhibitory step regulated by lateral root primordia can be located after hormonal signaling steps.

• Journal of the korean academy of Pediatric Dentistry
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• v.10 no.1
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• pp.67-76
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• 1983

The state of pulp and dental hard tissue during the process of resorption and shedding of 104 non-carious primary teeth was assessed by histomorphologic study. The teeth were extracted from the Korean school children aged 5 to 15 and classified into preshedding, shedding, delayed shedding groups according to the age of the child at the time of extraction, The results were as follows: 1. The inflammatory cell infiltration in primary pulp tissues occurred in 61.5% of observed teeth and were increased in the order of preshedding, shedding and delayed shedding stages. 2. The odontoclasts were appeared in 43.3% of observed teeth and were increased in the order of preshedding, shedding and delayed shedding stages. 3. The polymorphonuclear leukocytes and odontoclasts couldn't be observed in the exfoliated primary pulp tissues before the process of resorption has involved the root surface about 1.8mm subjacent to the cemento-enamel junction. 4. The intact root surface was the longest and largest in the preshedding stage. 5. The resorption process of primary teeth roots occurred mainly in the stage of preshedding and shedding stages. 6. There was a tendency of repair of resorbing root surfaces in the delayed shedding stage.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.290-295
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• 2011

During tooth formation, tooth development can be affected by physical action or metabolic changes around dental follicle. Especially trauma to primary dentition is the most representative physical factor that can cause development disorders of succedaneous tooth. Enamel hypoplasia and crown discoloration of succedaneous tooth are common complications of trauma. And impaction, ectopic eruption, arrest of root formation and root dilaceration of succedaneous tooth are rare. In this case, a 6-year and 5-month-old female patient visited for dental evaluation after trauma. She was diagnosed with alveolar bone fracture near upper front teeth, extrusion of the upper right and left primary central incisors, intrusion of the upper right primary lateral incisor, and palatal luxation of the upper left primary lateral incisor. Upper right and left primary central incisors with severe mobility were extracted, with gingival suture on the day of the visit. During 24 months check up, root dilacerations were found near the cemento enamel junction in the upper lateral incisors and arrests of root formation were found on the coronal 1/3 of the root in the upper central incisors. Although alveolar bone fracture is rare type of trauma in children, a thorough examination of alveolar bone is essential for prognosis and following treatment in patients with trauma.

• Journal of Biosystems Engineering
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• v.42 no.3
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• pp.227-233
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• 2017

Purpose: Morphological properties of soybean roots are important indicators of the vigor of the seed, which determines the survival rate of the seedlings grown. The current vigor test for soybean seeds is manual measurement with the human eye. This study describes an application of a machine vision technique for rapid measurement of soybean seed vigor to replace the time-consuming and labor-intensive conventional method. Methods: A CCD camera was used to obtain color images of seeds during germination. Image processing techniques were used to obtain root segmentation. The various morphological parameters, such as primary root length, total root length, total surface area, average diameter, and branching points of roots were calculated from a root skeleton image using a customized pixel-based image processing algorithm. Results: The measurement accuracy of the machine vision system ranged from 92.6% to 98.8%, with accuracies of 96.2% for primary root length and 96.4% for total root length, compared to manual measurement. The correlation coefficient for each measurement was 0.999 with a standard error of prediction of 1.16 mm for primary root length and 0.97 mm for total root length. Conclusions: The developed machine vision system showed good performance for the morphological measurement of soybean roots. This image analysis algorithm, combined with a simple color camera, can be used as an alternative to the conventional seed vigor test method.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.625-630
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• 2009

Root resorption of primary teeth usually occurs as the succeeding permanent teeth erupt, which induces differentiation of the hemopoietic cells into osteoclasts. Their root resorption pattern reflects the eruption path of the succeeding permanent teeth, and eventually the primary teeth shed as their succeeding permanent teeth erupt. Even when a permanent tooth germ is congenitally missing, root resorption of the corresponding primary tooth may still occur due to various factors, such as inflammation, traumatic occlusal force, and weakness of periodontium etc. Such congenital missing of permanent teeth is a commonly observed phenomenon in human be ing, and it often accompanies delayed retention of primary teeth. The etiologic factors for congenital missing in elude not only systemic diseases, but also local factors and human evolution process. In the radiographs of the cases in this report, the primary teeth without succeeding permanent teeth show pathologic root resorption. Root resorption progressed about 1/2~3/4 of the roots, and the surfaces of the resorption area were irregular. Considering high susceptibility of the periodontal ligament of primary teeth to root resorption, pathologic root resorption of primary teeth with delayed retention can be explained by the increased masticatory muscle force and abnormal occlusion developed during the mixed dentition. When the primary teeth without succeeding permanent teeth are lost, decision for space maintenance is required and long-term treatment plan for further prosthetic or orthodontic treatment should be establsihed.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.4
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• pp.437-448
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• 2021

The purpose of this study is to analyze morphological characteristics of maxillary primary molar's root and root canal. 268 children aged 3 - 7 years (175 boys, 93 girls) who had CBCT (152 children) and 3D CT (116 children) taken in Seoul National University Dental Hospital from January 2006 to April 2020 were included. The number of roots and root canals were analyzed in 1002 teeth without any root resorption or periapical pathologies. Curvature, angulation, length of root and root canal, as well as cross-sectional shapes of the root canal were analyzed in 218 teeth. By using Mimics and 3-Matics software, volume, surface area, and volume ratio of root canal was analyzed in 48 teeth. More than half of maxillary primary molars have 3 roots and 3 root canals. The degree of symmetry of root canal type was about 0.63 (Cohen's kappa coefficient). The most frequent shape of roots and canals was linear in 1^st primary molars and curved in 2^nd primary molars. Angulation, length of root and root canals was the largest on palatal roots. Most teeth showed ovoid or round shapes at apex. The largest root canal volume, surface area, volume ratio was found in the palatal roots.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.337-343
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• 2020

Molar-incisor malformation (MIM) is a new type of root anomaly reported recently. The characteristics of MIM are dysplastic root formations, constriction of pulp chambers and presence of calcified matrices at the level of cementoenamel junction in permanent first molars and primary second molars. In some cases, permanent maxillary incisors are also affected. The permanent first molars of the patient in this case report were affected with MIM. Generalized pulp stones were observed in overall primary dentition. Micro-computed tomography (micro-CT) imaging and scanning electron microscope-energy dispersive X-ray spectrometer analysis were performed on the extracted mandibular first molar and maxillary primary second molar of the patient. Micro-CT images revealed the discontinuity of enamel directly connected to an accessory canal of the root.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.776-780
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• 1997

Patient with alveolar abscess due to dental caries with severe alveolar bone loss, severe tooth mobility, root resorption need extraction of tooth because it is impossible to carry out pulp treatment and restoration by using conventional method. Early loss of primary molar might cause masticatory interference, extrusion of opposing tooth, problem in maintaining space and interference on eruption of permanent tooth. Especially, early loss of primary second molar before the eruption of permanent first molar might cause space closure by mesially erupted permanent first molar and impaction of second premolar. In such a case, distal shoe space maintainer and removable space regaining appliance was the first choice of treatment. But, distal shoe space maintainer need precise adaptation and might cause chronic inflammation if the oral hygiene is poor. In a case using removable space regaining appliance, patient's cooperation is most important. If the distal root of primary second molar is comparably sound and alveolar abscess with alveolar bone loss is localized at mesial root, hemisection should be carried out for precise guide to eruption of the permanent first molar, restoration of masticatory fuction and solution to the discomfort of the patient

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.420-428
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• 1988

Root is supposed to be important role in growth and yield formation of soybeans and also there is expected to exist varietal differences between soybean root morphology and system. 30 soybean varieties including 10 Korean recommended, 10 Introduced and 10 Korean native varieties were grown at field and pot under standard culture condition. Top and root characteristics were investigated at V4, R1 and R5 stage and T/R relations, correlations with yield were calculated. Top characteristics showed significant difference between 3 variety groups of Korean recommended, Introduced and Korean native variety. Stem length at R1 stage and stem length, stem diameter, number of nodes, number of branches, number of pods and grain yield at R5 stage were significantly different top characteristics. Root characteristics showed significant difference between 3 variety groups were number of thick primary root at V4 stage, primary root angle and root cutting strength at R1 stage, thick root diameter and root dry weight at R5 stage. The correlations between top and root characteristics and soybean yield was greatly different by soybean variety groups, and the top characteristics was more highly correlated then root characteristics. All the top and root characteristics of Korean recommended variety showed no correlations with yield. However, leaf area, stem length, top dry weight in Introduced variety and leaf area, top dry weight, number of nodes, number of thick primary root in Korean native variety were highly correlated with soybean yield.