• Investigative Magnetic Resonance Imaging
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• v.7 no.1
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• pp.47-55
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• 2003

Purpose : Cortical dysplasia is known to be of variety of MR imaging findings. We attempted to classify MR imaging findings of cortical dysplasia into several types and to correlate those with histopathologic grades and subtypes. Materials and Methods : Preoperative MR images of 97 patients with pathologically-proven cortical dysplasia were retrospectively reviewed with knowledge of the diagnosis and operative sites. The patients were divided into MR-positive and MR-negative groups based on the presence or absence of MR imaging abnormalities. In MR-positive group, MR imaging features were arbitrarily classified into four types (atrophic, cortical-band, inward-rounding, and nonspecific types) on the basis of size of the gyrus and adjacent CSF space, cortical thickness, signal intensity of the subcortical white matter, and blurring of the gray-white matter junction. The pathologic findings were also retrospectively reviewed without knowledge of MR imaging findings and divided into three grades (mild, moderate, and severe) and two subtypes (nonballoon-cell and balloon-cell). Pathologic grades and subtypes we re compared between MR-positive and MR-negative groups. Four MR types of the MR-positive group were correlated with the pathologic grades and subtypes. Results : MR-positive and MR-negative groups consisted of 39 (40%) and 58 (60%) patients, respectively. Of the MR-positive group, atrophic type was seen in 13 patients (33 %), cortical-band type in 9 (23%), inward-rounding type in 9 (23%), and nonspecific type in 8 (21%). There was no significant difference in the pathologic grades between MR-positive and MR-negative groups, although MR-positive group tended to have higher pathologic grades than MR-negative group did. Balloon-cell subtype was found significantly higher in MR-positive group than in MR-negative group (p<0 .05): 21% (8/39) versus 5% (3/58). The inward-rounding type corresponded to the pathologically severe grade and balloon-cell subtype in 78% (7/9) and 56% (5/9) of the patients, respectively, while the atrophic type to the mild grade and nonballoon-cell subtype in 77% (10/13) and 100% (13/13), respectively. Conclusion : A variety of MR imaging abnormalities were found in 40% of the patients with cortical dysplasia and those were classified into four types (atrophic, cortical-band, inward-rounding, and nonspecific types), of which the inward-rounding type correlated well with the pathologically severe grade and balloon-cell subtype, whereas the atrophic type with the mild grade and nonballoon-cell subtype.

• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.435-441
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• 2002

Surgical microscrews were introduced and used as one method to provide absolute anchorage. Some clinicians implanted microscrews or miniscrews into the basal bone below the roots of the teeth to evade damage to the roots. Because the implanted microscrews were positioned too low the applied force was insufficient to retract the anterior teeth or protract the posterior teeth, and the use of microscrews or miniscrews seemed limited in applying vertical force. However Park implanted microscrews(micro-implants (1.2mm in diameter)) into the alveolar bone between the roots of the posterior teeth to change the direction of the applied force toward increasing horizontal component of the force. Moreover, these microscrew implants were positioned in the alveolar bone between the roots without causing discernable damage to the roots. This study was performed to provide guidelines and anatomic data to assist in the determination of the safe location for micro-implants. By measuring the CT images from 21 patients, anatomical data were obtained which were then used as a guide to determine the location for the implantation of micro-implants. The thickness of the cortical bones at the alveaolar bone region increased from the anterior to the posterior teeth area. The mandibular posterior teeth area showed thicker cortical bone. A greater distance was observed in distance between the second premolar root and first molar root in the upper arch, between the first molar root and the second molar root in the lower arch. The alveolar bone of the posterior teeth area is considered the best site for the implantation of micro-implants.

• The Korea Journal of Herbology
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• v.20 no.4
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• pp.83-94
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• 2005

Objectives : The present study attempted to reveal the effects of Morindae Radix extracts on the sciatic nerve neurectomized osteoporotic ddy mice model. Methods : Thickness of hind limbs and their differences, absolute and relative tibia weight and thickness, bone failure load, bone mineral density (BMD), histomorphometrical index, serum osteocalcin level, tibia calcium and phosphorus contents were monitored. Results : In sciatic neurectomized mice, thickness of hind limb, absolute and relative weights, thickness, failure loads, BMD of tibia, trabecular bone volume (TBV), thickness of trabecular bone and cortical bone thickness, length were significantly decreased. However, these changes of those dose-dependently reduced in MR extract-dosing group. Conclusions : it is considered that MR extracts have some favorable effect to prevent, the osteoporosis induced by sciatic neurectomy. However, the exact mechanism and the possibility of MR extract were remains unknown. In addition, the potential toxicity of these MR extracts were also unknown. So the further studies were needed about toxicological and pharmacological aspects.

• The korean journal of orthodontics
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• v.41 no.6
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• pp.423-430
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• 2011

Objective: To evaluate the extent and aspect of stress to the cortical bone after application of a lateral force to a two-component orthodontic mini-implant (OMI, mini-implant) by using three-dimensional finite element analysis (FEA). Methods: The 3D-finite element models consisted of the maxilla, maxillary first molars, second premolars, and OMIs. The screw part of the OMI had a diameter of 1.8 mm and length of 8.5 mm and was placed between the roots of the upper second premolar and the first molar. The cortical bone thickness was set to 1 mm. The head part of the OMI was available in 3 sizes: 1 mm, 2 mm, and 3 mm. After a 2 N lateral force was applied to the center of the head part, the stress distribution and magnitude were analyzed using FEA. Results: When the head part of the OMI was friction fitted (tapped into place) into the inserted screw part, the stress was uniformly distributed over the surface where the head part was inserted. The extent of the minimum principal stress suggested that the length of the head part was proportionate with the amount of stress to the cortical bone; the stress varied between 10.84 and 15.33 MPa. Conclusions: These results suggest that the stress level at the cortical bone around the OMI does not have a detrimental influence on physiologic bone remodeling.

• Journal of Korean Neurosurgical Society
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• v.39 no.2
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• pp.125-129
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• 2006

Objective : The purpose of this study is to identify any differential point in computerized tomographic[CT] findings between aneurysmal subarachnoid hemorrhage[ASAH] and traumatic subarachnoid hemorrhage[TSAH], which sometimes make us not confident in differentiation. Methods : CT of 142 ASAH and 82 TSAH patients over the last 2 years were retrospectively reviewed. We evaluated the thickness of SAH, the laterality of sylvian cisternal hemorrhage, the location, the number of involved cisterns, and the associated other lesions between two types of SAH. Results : Suprasellar cisterns and sylvian cisterns were most prominently and frequently involved cisterns in ASAH but cortical sulci and sylvian cisterns were most frequently involved in TSAH. Intraventricular and intracerebral hemorrhage were frequently seen in ASAH. Thickness of SAH over 1mm, bilateral sylvian SAH, multiple cisternal SAH were in favor of ASAH. The number of involved cisterns were more frequently seen in ASAH than in TSAH. In ASAH, bilateral sylvian hemorrhages were more frequently seen than in TSAH. Skull fracture, subdural hematoma, subgaleal hematoma, and hemorrhagic contusion were frequently associated with TSAH. Conclusion : As a result of our study, the authors conclude that when IVH, hydrocephalus, thick SAH > 1mm bilateral sylvian SAH, and multiple cisternal SAH are seen in CT, immediate angiography should be performed to rule out cerebral aneurysms whether associated with other traumatic lesions or not.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.5
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• pp.233-239
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• 2014

Implants are typically placed after performing ridge expansion by inserting screws of gradually increasing thickness and good clinical outcomes are often obtained. We placed 11 implants in 6 patients, and one implant failed during osseointegration but it was replaced immediately after removal and successful prosthetic treatments were completed. During these surgeries, buccal cortical plate complete fractures do not occur. Inserting screws for ridge expansion is a successful and predictable technique for implant placement in narrow alveolar bone.

• Korean Journal of Cleft Lip And Palate
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• v.15 no.2
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• pp.51-60
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• 2012

Craniofacial sutures absorb the stress transferred to skull. It was reported the cells of craniofacial sutures respond to exogenetic factors to be involved in growth control mechanism. In this study, we constructed a finite element model composed of cortical bone, cancellous bone, suture, PDL, and teeth by using CT images of a growing patient, simulating maxillary expansion to evaluate the effects of the thickness of sutures and type of maxillary expansion appliance on stress distribution in circummaxillary sutures.

• Applied Microscopy
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• v.46 no.4
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• pp.179-183
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• 2016

Mapping brain structural and functional connections through the whole brain is essential for understanding brain mechanisms and the physiological bases of brain diseases. Although region specific structural or functional deficits cause brain diseases, the changes of interregional connections could also be important factors of brain diseases. This review will introduce common neuroimaging modalities, including structural magnetic resonance imaging (MRI), functional MRI (fMRI), diffusion tensor imaging, and other recent neuroimaging analyses methods, such as voxel-based morphometry, cortical thickness analysis, local gyrification index, and shape analysis for structural imaging. Tract-Based Spatial Statistics, TRActs Constrained by UnderLying Anatomy for diffusion MRI, and independent component analysis for fMRI also will also be introduced.

• Journal of Periodontal and Implant Science
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• v.45 no.2
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• pp.62-68
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• 2015

Purpose: The goal of this study was to investigate the histomorphometric characteristics of the healing process of microcracks in the cortical bone after the installation of mini-implants (MIs). Methods: Self-drilling MIs were inserted into the tibial diaphysis of twelve adult male New Zealand rabbits. Four MIs per rabbit were placed randomly. The animals were divided into four groups according to the length of the healing period: group A was sacrificed immediately, group B was sacrificed after one week, group C was sacrificed after two weeks, and group D was sacrificed after four weeks. Cortical bone thickness was measured using micro-computed tomography, and histomorphometric analyses of the cumulative length of the microcracks (CLCr) and the total number of microcracks (NCr) were performed using hematoxylin and eosin staining. Results: The microcracks were radially and concentrically aligned in the peri-MI bone. The CLCr decreased significantly one week after the surgery, mainly due to healing of the concentrically aligned microcracks. The CLCr showed another significant decrease from two weeks after the surgery to four weeks after the surgery, mainly reflecting healing of the radially aligned microcracks. A statistically significant decrease in the NCr occurred as the microcracks healed from zero weeks to two weeks. However, no significant difference in the NCr was found between groups C and D. Conclusions: In order to improve the primary stability of MIs, delayed loading and a healing period of a certain length are recommended to ensure the optimal healing of microcracks and bone remodeling.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.12-25
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• 2000

To demonstrate possible influences of general bone density on the mandible, histomorphometric analysis was carried out in mandibles and iliac bones and the correlation of the two bone densities was tested. Comparison of bony density in women and men over 60 years in the mandible was carried out too. Quantitative computed tomography(QCT) was taken in cross-section of mandibles at the same site where histomorphometric analysis was peformed to evaluate the reliability of QCT. The analysis included 40 cadavers with no known diseases affecting the bones. The subjects consisted of 15 females and 25 males with a mean age of 60.3 years. Spearman correlation analysis and Wilcoxon rank sum test was performed. The results were as follows. 1. There was statistically no correlation between the mandible and iliac bone in the values of corrected cortical width(CCW), cortical porosity(POR) in cortex, and total bone volume(TBV), mean trabecular plate thickness(MTPT), mean trabecular plate density(MTPD), and mean trabecular plate separation(MTPS) in trabecular bone. 2. Comparison of women and men over 60 years, men had statistically higher bone density than women except fir POR of buccal and lingual cortex, and WTPD of alveolar trabeculae in mandible. 3. There was statistically significant correlation between TBV of trabecular bone and CT No., but not between POR and CT No. in mandible. According to the results above, there was no correlation between mandible and iliac bone density and between mandibular bony density and age. Further studies are required to support the results. A more noninvasive method to be able to measure the bone density of mandible should be developed and it is necessary to accumulate data on the normal values of bone density of mandible according to age and sex. Further study should be carried out about QCT to measure mandibular bony density using QCT.