• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.14 no.1
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• pp.169-172
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• 1984

The author observed a cystic lesion which had new radiographic entities in the 6 years old male patient and obtained the following features. 1. The main clinical feature is the swelling. 2. The lesion is situated on the buccal surface of a erupting mandibular first molar. 3. The affected molar is tilted, so that the apices are adjacent to the lingual plate of the mandible. 4. The affected molar is of normal morphology, caries-free and vital. 5. The radiographic feature is the cystic radiolucency which is extended over the buccal surface of the roots of the affected molar and slightly inferior to the root apices. 6. The dental papilla of the affected molar shows the lamina dura of relatively normal density and definitition. 7. The buccal surface shows the laminated new bone formation. 8. The inferior concave border of the lesion is delineated by a thick and calcified layer of cortical bone. 9. The lesion causes displacement of the developing second molar of which anterior cortex is partially destroyed.

• Journal of Periodontal and Implant Science
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• v.25 no.1
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• pp.67-75
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• 1995

The progress of periodontal disease and the wound healing process after treatment result in alveolar bone bone change. So, detection of it is very important in the diagnosis and the radiograph of periodontal disease. Various effects have been made to assess the subtle alveolar bone change and digital subtraction radiography (DSR) has been reported to be the best method in evaluating it qualitatively and quantitatively. The present study was performed to estimate the detectable alveolar bone change qualitatively with digital subtraction radiography. For the in vitro study, 10 intraoral standard radiographs were taken from porcine dry mandible which a rectangular cortical bone chip of 0.1mm to 1.0mm thickness with 0.1mm increment was attached on the buccal surface. The radiographs without and with bone plates were reviewed at the same time by 10 observers and requested to detect the presence of cortical bone plates. Digital Subtraction radiograph was reviewed subsequently by using the DSR system(digital converter-256 grey-levels,DT 2851,Data Translation Co., U.S.A;IBM 386 ; CCD camera, FOTOVIX, Tamrom Co., Japan). The detectable thickness of cortical bone plate was O.4mm on the intraoral radiograph and 0.2mm on the subtaction images. For the human study, radiographs were taken from patients by using intraoral film holding device and aluminum reference wedge before and 3 month after bone graft and 1 week after osteoplasty. The grey level change was estimated in the subtraction images and calculated to aluminum equivalent thickness. The grey level of the grafted site was higher that that of healthy controls. Average grey levels of change on healthy controls were O.48mm aluminum equivalent. However, the amount of changes in grafted sites were 1.87mm aluminum thickness equivalent and in the site of osteoplasty were -1.49mm aluminum thickness equivalent. In conclusion, digital subtraction radiography was more effective in detecting as subtle change of alveolar bone than intraoral standard radiography. With the aid of quantitative analysis of digital subtraction radiography, alveolar bone resorption of apposition can be estimated during diagnosis and treatment of periodontally diseased patients.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.517-538
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• 1995

Dental implantation is a method restoring missing teeth, especially in the case of severely resorbed edentulous patient. But the direct contact between bone and implant surface, induces stress concentration to the bone and eventually becomes a cause. The purpose of this study was to compare the stress distribution patterns between following two cylindrical implant models. One group has implant apex located in the inferior cortical bone and the other in the cancellous bone. Anterior edentulous mandible was modeled with two dimensional 953,878 nodes, 995,918 elements and compared the deflection and stress distribution under the 70 N,4 load cases for 26 models having variant mandibular height and length. The result were as follows; 1. The stress concentration was more affected by the height of the mandible than implant length. 2. Bicortication mitigates the stress of upper cortical and cancellous bone area at the same height of the mandible 3. Perforation of the inferior mandibular cortex significant stress concentration. 4. Stud type porstheses induced less stress concentration to the cortical and cancellous bone than bar type prostheses. 5. Stress of implant apex for stud type was larger than that of bar type.

• Journal of Periodontal and Implant Science
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• v.46 no.5
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• pp.291-302
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• 2016

Purpose: The aim of the present study was to evaluate the effectiveness of using a mineralized bone cortical allograft (MBCA), with or without a resorbable collagenous membrane derived from bovine pericardium, on alveolar bone remodeling after immediate implant placement in a dog model. Methods: Six mongrel dogs were included. The test and control sites were randomly selected. Four biradicular premolars were extracted from the mandible. In control sites, implants without an allograft or membrane were placed immediately in the fresh extraction sockets. In the test sites, an MBCA was placed to fill the gap between the bone socket wall and implant, with or without a resorbable collagenous membrane. Specimens were collected after 1 and 3 months. The amount of residual particles and new bone quality were evaluated by histomorphometry. Results: Few residual graft particles were observed to be closely embedded in the new bone without any contact with the implant surface. The allograft combined with a resorbable collagen membrane limited the resorption of the buccal wall in height and width. The histological quality of the new bone was equivalent to that of the original bone. The MBCA improved the quality of new bone formation, with few residual particles observed at 3 months. Conclusions: The preliminary results of this animal study indicate a real benefit in obtaining new bone as well as in enhancing osseointegration due to the high resorbability of cortical allograft particles, in comparison to the results of xenografts or other biomaterials (mineralized or demineralized cancellous allografts) that have been presented in the literature. Furthermore, the use of an MBCA combined with a collagen membrane in extraction and immediate implant placement limited the extent of post-extraction resorption.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.299-310
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• 2008

In this study, the regression analysis method was tested for the estimation of peak stress at stress concentration area in the cervical bone. Submerge type EZ plus implant (Megagen. Daegu, Korea), 4.1 mm in cervical diameter and 9.6 mm in endosseous length, were axisymmetrically modelled together with surrounding alveolar bone of which the width was 10 mm. Vertical force of 100 N was applied to a head of crown above 8.5 mm from the outer surface of the cortical bone. Four different mesh models were composed of differently sized elements in vicinity of sharp corners, and they include 6 stress monitoring points that are located in the same geometrical points regardless of the differences in the meshes. Primary consideration was given to the stresses in the cortical bone surrounding the implant neck. The results showed that virtually all the stresses were concentrated in the cortical bone regardless of mesh designs. The peak stresses were successfully calculated by a regression analysis in a stable manner, as far as the mesh is designed to represent the acute gradient of stresses near the sharp corner.

• The Korean Journal of Physiology
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• v.25 no.1
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• pp.61-67
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• 1991

In order to determine possible relationships between the renin-angiotensin system and nephron heterogeneity, we compared the response of renin release and the angiotensin-converting enzyme (ACE) activity from different areas of the rat kidney. We used the renal cortical slices from the capsular surface to the juxtamedullary junction. Slices from outer one-third of the cortex were designated as outer cortical slices (OC), middle one-third as midcortical slices (MC), and inner one-third as inner cortical slices (IC). The renal renin content markedly decreased from OC and MC to IC. The basal lenin release was higher in OC than in MC or IC. On the contrary the percent change of renin release in response to L-isoproterenol was significantly higher in MC than in OC or IC. By TMB-8, the renin release in MC by $231{\pm}21%$ was higher than OC by $171{\pm}19%$ or IC by $$162{\pm}19. Angiotensin II suppressed renin release in OC and MC by $68{\pm}2,\;71{\pm}4%$ respectively, but only $40{\pm}7%$ in IC. The ACE activity was higher in IC than in OC, MC, medulla and papilla. The present data indicate that renin content and basal lenin release gradulally decreased from outer (OC) to inner (IC) cortex. The renin release in response to beta-adrenergic agonist, L-isoproterenol and intracellular calcium antagonist, TMB-8 were higher in MC than in OC and IC, but angiotensin II suppressed renin release less in IC than in OC and MC. It is suggested that juxtaglomerular cells of outer, mid-and inner cortices show a difference in renin release response to the stimuli.

• 한국당과학회:학술대회논문집
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• 2006.11a
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• pp.53-54
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• 2006

• Mycobiology
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• v.31 no.1
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• pp.1-8
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• 2003

Detailed structures of ectomycorrhizae formed in Pinus roots were observed with various microscopes: light, fluorescence, and scanning electron microscopes. The mantles and Hartig nets commonly found in the structure of ectomycorrhiza were newly observed according to developmental stage by various staining. The mycelia were observed to be composed of coiled types on the surface of epidermal root during early stage and fused to form mantles of smooth fungal layers, loosing mycelia with some viscous liquid secreted. The ectomycorrhizal hyphae in anatomical roots penetrated the cortical layer and formed obviously mantle and Hartig net. The round spots of ectomycorrhizal mycelia were observed morphological distribution from the cortical layer to vascular bundle of stele in the ectomycorrhizal roots of Pinus species and especially scattered at the area of meristem at the root tip as longitudinal sections. Those mycelia penetrated seemed to move into other roots by means of vascular bundle of ectomycorrhizal roots and newly form ectomycorrhizal roots of dichotomous branches.

• The Plant Pathology Journal
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• v.25 no.2
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• pp.113-120
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• 2009

Microscopic study of chili pepper (Capsicum annuum L.) infected with Phytophthora capsici, causing Phytophthora blight of chili pepper, was conducted to compare histological and cytological characteristics in the root and stem of susceptible (C. annuum cv. Bugang) and resistant (C. annuum cv. CM334) pepper cultivars. The susceptible pepper roots and stems were extensively penetrated and invaded by the pathogen initially into epidermal cells and later cortical and vascular cells. Host cell walls adjacent to and invaded by the infecting hyphae were partially dissolved and structurally loosened with fine fibrillar materials probably by cell wall-degrading enzymes of the pathogen. In the resistant pepper, the pathogen remained on root epidermal surface at one day after inoculation, embedded and captured in root exudation materials composed of proteins and polysaccharides. Also the pathogen appeared to be blocked in its progression at the early infection stages by thickened middle lamellae. At 3 days after inoculation, the oomycete hyphae were still confined to epidermal cells of the root and at most outer peripheral cortical cells of the stem, resulting from their invasion blocked by wound periderms formed underneath the infection sites and/or cell wall appositions bounding the hyphal protrusions. All of these aspects suggest that limitation of disease development in the resistant pepper may be due to the inhibition of the pathogen penetration, infection, invasion, and colonization by the defense structures such as root exudation materials, thickened middle lamellae, wound peridems and cell wall appositions.

• Journal of Korean Foot and Ankle Society
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• v.15 no.3
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• pp.149-152
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• 2011

Purpose: The Akin osteotomy which is a closing wedge osteotomy of the proximal phalanx widely used for the correction of hallux valgus has several methods of fixation. we tried to report the effects of the fixation using an absorbable suture material during the Akin osteotomy for the hallux valgus. Materials and Methods: This study was based on 448 cases of 346 patients who were able for follow-up more than 12 months among the patients who had an Akin osteotomy together with the surgery of hallux valgus between March of 2006 and May of 2010. Absorbable suture material had been used in all cases. Radiologically displacement and union of osteotomy site were observed after the surgery, and clinically postoperative complication such as skin irritation, pain and satisfaction were investigated. Results: Radiologically all cases had showed complete union and no case had the loss of an correction due to loss of fixation. Also, any case had no skin irritation due to a knot. Three cases had a medial cortical breakage due to a strong knot, and the initial one case among them had additionally fixed the osteotomy site for four weeks using K-wire, and the remaining two cases had fixed a suture on an articular surface without any fixation of an additional wire. If a medial cortical bone was lost by carrying out an ostectomy due to proximal protrusion of proximal phalanx, three cases could show union through the fixation of suture on an articular surface. Conclusion: This study considers that the fixation of the osteotomy site using an absorbable suture material in an Akin osteotomy was effective method and the advantage of this procedure was unnecessity of the material removal and no skin irritation.