1.Biomechanical stress and microgap analysis of bone-level and tissue-level implant abutment structure according to the five different directions of occlusal loads
Jae-Hoon KIM ; Gun woo NOH ; Seoung-Jin HONG ; Hyeon jong LEE
The Journal of Advanced Prosthodontics 2020;12(5):316-321
PURPOSE:
The stress distribution and microgap formation on an implant abutment structure was evaluated to determine the relationship between the direction of the load and the stress value.
MATERIALS AND METHODS:
Two types of three-dimensional models for the mandibular first molar were designed: bone-level implant and tissue-level implant. Each group consisted of an implant, surrounding bone, abutment, screw, and crown. Static finite element analysis was simulated through 200 N of occlusal load and preload at five different load directions: 0, 15, 30, 45, and 60°. The von Mises stress of the abutment and implant was evaluated. Microgap formation on the implant-abutment interface was also analyzed.
RESULTS:
The stress values in the implant were as follows: 525, 322, 561, 778, and 1150 MPa in a bone level implant, and 254, 182, 259, 364, and 436 MPa in a tissue level implant at a load direction of 0, 15, 30, 45, and 60°, respectively. For microgap formation between the implant and abutment interface, three to seven-micron gaps were observed in the bone level implant under a load at 45 and 60°. In contrast, a three-micron gap was observed in the tissue level implant under a load at only 60°.
CONCLUSION
The mean stress of bone-level implant showed 2.2 times higher than that of tissue-level implant. When considering the loading point of occlusal surface and the direction of load, higher stress was noted when the vector was from the center of rotation in the implant prostheses.
2.Endovascular Coiling for a Wide-neck Bifurcated Aneurysm with Anterograde Horizontal Stenting via Microcatheter Looping: A Technical Case Report.
Hyun Jae JEON ; Jong Hwa PARK ; Jong Young LEE ; Hong Jun JEON ; Seoung Woo PARK ; Byung Moon CHO
Journal of Cerebrovascular and Endovascular Neurosurgery 2018;20(3):181-186
Technical advances with devices such as catheters, balloons, and stents have widened the indications for endovascular coiling for unfavorable aneurysms. The authors report two cases of coil embolization for a wide-neck bifurcated aneurysm with anterograde horizontal stenting via microcatheter looping. Two women, aged 56 and 38 years, respectively, had an undertall- and overwide-neck aneurysm with bifurcated branches at the basilar bifurcation and middle cerebral bifurcation, respectively. The delivery microcatheter was steamed so that it could be looped deliberately to the opposite vessel. The enterprise stent was first anchored to the vessel of the posterior cerebral artery on one side. The remaining portion was spanned into a looped microcatheter to the opposite branch while pushing the stent. The Neuroform Atlas stent was passed directly through the looped segment of the microcatheter at the M2 branch and spanned horizontally by unsheathing. Under horizontal stenting, complete coil embolization was achieved without immediate or delayed complications in both cases. This novel technique presents a viable option for stent-assisted coiling within an optimal anatomy.
Aneurysm*
;
Catheters
;
Embolization, Therapeutic
;
Female
;
Humans
;
Intracranial Aneurysm
;
Posterior Cerebral Artery
;
Steam
;
Stents*
3.Single-Stage Operation for Giant Schwannoma at the Craniocervical Junction with Minimal Laminectomy: A Case Report and Literature Review.
Sun YOON ; Hunho PARK ; Kyu Sung LEE ; Seoung Woo PARK ; Chang Ki HONG
Korean Journal of Spine 2016;13(3):173-175
Here we report a single-stage operation we performed on a patient with a large schwannoma that extended from the lower clivus to the cervico-thoracic junction caudally. A number of authors have previously performed multilevel laminectomy to remove giant schwannomas that extend for considerable length. This technique has caused cervical instability such as kyphosis or gooseneck deformity on several occasions. We removed the tumor with a left lateral suboccipital craniectomy with laminectomy only at C1 and without any subsequent surgery-related neurologic deficits. However, this technique requires meticulous preoperative evaluation on existence of Cerebrospinal fluid (CSF) cleft between the tumor and spinal cord on magnetic resonance imaging, of tumor origin located at the upper cervical root, and of detachment of tumor from the origin site.
Cerebrospinal Fluid
;
Congenital Abnormalities
;
Cranial Fossa, Posterior
;
Humans
;
Kyphosis
;
Laminectomy*
;
Laminoplasty
;
Magnetic Resonance Imaging
;
Neurilemmoma*
;
Neurologic Manifestations
;
Spinal Cord
;
Spinal Cord Neoplasms
4.Surgical Treatment for Falcotentorial Meningiomas.
Chang Ki HONG ; Je Beom HONG ; Hunho PARK ; Ju Hyung MOON ; Jong Hee CHANG ; Kyu Sung LEE ; Seoung Woo PARK
Yonsei Medical Journal 2016;57(4):1022-1028
Among intracranial meningiomas, falcotentorial meningiomas, occurring at the junction of the falx cerebri and tentorial dural folds, are extremely rare. Because of their deep location, they are surrounded by critical structures, and have been regarded as one of the most challenging lesions for surgical treatment. In this study, we describe our surgical strategy for falcotentorial meningiomas and provide a review of our experience.
Adult
;
Aged
;
Dura Mater/pathology
;
Female
;
Humans
;
Male
;
Meningeal Neoplasms/pathology/*surgery
;
Meningioma/pathology/*surgery
;
Middle Aged
5.Midterm Outcome of Femoral Artery Stenting and Factors Affecting Patency.
Jae Seoung YU ; Keun Myoung PARK ; Yong Sun JEON ; Soon Gu CHO ; Kee Chun HONG ; Woo Young SHIN ; Yun Mee CHOE ; Seok Hwan SHIN ; Kyung Rae KIM
Vascular Specialist International 2015;31(4):115-119
PURPOSE: The purpose of this study was to evaluate the early and midterm results of superficial femoral artery (SFA) stenting with self-expanding nitinol stents and to identify the factors affecting patency. MATERIALS AND METHODS: SFA stenting was performed in 165 limbs of 117 patients from January 2009 to December 2013. Patients were followed-up for the first occurrence of occlusion or stenosis based on computed tomography and duplex scan results and a decrease in ankle brachial index of >15%. RESULTS: During the follow-up period (mean, 15.3+/-3.2 months), no early thrombotic reocclusions occurred within 30 days, but in-stent restenosis developed in 78 limbs. The primary patency rates at 6, 12, 18, and 24 months were 78%, 66%, 42%, and 22%, respectively, and the secondary patency rates were 85%, 72%, 58%, and 58%, respectively. TASC II C or D lesions, stent length >8 cm, number of patent tibial arteries and diabetes were significantly associated with reintervention. CONCLUSION: The midterm results of stenting for SFA occlusive disease were disappointing because the primary and secondary patency rates at two years were 22% and 58%, respectively. Reintervention after SFA stenting remains a major problem, particularly in patients with diabetes mellitus or long TASC II C or D lesions.
Ankle Brachial Index
;
Constriction, Pathologic
;
Diabetes Mellitus
;
Endovascular Procedures
;
Extremities
;
Femoral Artery*
;
Follow-Up Studies
;
Humans
;
Stents*
;
Tibial Arteries
6.Risk of Malignancy in Thyroid Incidentalomas Identified by Fluorodeoxyglucose-Positron Emission Tomography.
A Reum CHUN ; Hye Min JO ; Seoung Ho LEE ; Hong Woo CHUN ; Jung Mi PARK ; Kyu Jin KIM ; Chan Hee JUNG ; Ji Oh MOK ; Sung Koo KANG ; Chul Hee KIM ; Bo Yeon KIM
Endocrinology and Metabolism 2015;30(1):71-77
BACKGROUND: Thyroid incidentalomas detected by 2-deoxy-2-18F-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) have been reported in 1% to 4% of the population, with a risk of malignancy of 27.8% to 74%. We performed a retrospective review of FDG-avid thyroid incidentalomas in cancer screening subjects and patients with nonthyroid cancer. The risk of malignancy in thyroid incidentaloma and its association with the maximal standardized uptake value (SUVmax) in 18F-FDG PET/CT were evaluated to define the predictor variables in assessing risk of malignancy. METHODS: A total of 2,584 subjects underwent 18F-FDG PET/CT for metastatic evaluation or cancer screening from January 2005 to January 2010. Among them, 36 subjects with FDG-avid thyroid incidentalomas underwent further diagnostic evaluation (thyroid ultrasonography-guided fine needle aspiration cytology [FNAC] or surgical resection). We retrospectively reviewed the database of these subjects. RESULTS: Of the 2,584 subjects who underwent 18F-FDG PET/CT (319 for cancer screening and 2,265 for metastatic evaluation), 52 (2.0%) were identified as having FDG-avid thyroid incidentaloma and cytologic diagnosis was obtained by FNAC in 36 subjects. Of the subjects, 15 were proven to have malignant disease: 13 by FNAC and two by surgical resection. The positive predictive value of malignancy in FDG-avid thyroid incidentaloma was 41.7%. Median SUVmax was higher in malignancy than in benign lesions (4.7 [interquartile range (IQR), 3.4 to 6.0] vs. 2.8 [IQR, 2.6 to 4.0], P=0.001). CONCLUSION: Thyroid incidentalomas found on 18F-FDG PET/CT have a high risk of malignancy, with a positive predictive value of 41.7%. FDG-avid thyroid incidentalomas with higher SUVmax tended to be malignant.
Biopsy, Fine-Needle
;
Diagnosis
;
Early Detection of Cancer
;
Electrons
;
Fluorodeoxyglucose F18
;
Humans
;
Incidental Findings
;
Positron-Emission Tomography
;
Positron-Emission Tomography and Computed Tomography
;
Prevalence
;
Retrospective Studies
;
Thyroid Gland*
;
Thyroid Neoplasms
7.Mucosal Mast Cell Count Is Associated With Intestinal Permeability in Patients With Diarrhea Predominant Irritable Bowel Syndrome.
Hyuk LEE ; Jung Ho PARK ; Dong Il PARK ; Hong Joo KIM ; Yong Kyun CHO ; Chong Il SOHN ; Woo Kyu JEON ; Byung Ik KIM ; Seoung Wan CHAE
Journal of Neurogastroenterology and Motility 2013;19(2):244-250
BACKGROUND/AIMS: Although mucosal mast cell tryptase is known to significantly increase intestinal permeability, the relationship between mucosal mast cells and intestinal permeability remains unclear. The objective of this study was to evaluate the correlation among intestinal permeability, tryptase activity and mucosal mast cell count. METHODS: Rectal biopsies from 16 patients with diarrhea-predominant irritable bowel syndrome (IBS-D) and 7 normal subjects were assessed for tryptase activity and macromolecular permeability using horseradish peroxidase in Ussing chambers. In addition, mucosal mast cell levels were immunohistochemically quantified via image analysis. RESULTS: Rectal biopsy of tissues from IBS-D patients showed significantly increased permeability compared with those from normal controls (0.644 +/- 0.08 and 0.06 +/- 0.00 ng/2 hr/mm2, P < 0.01). Tryptase activity was also substantially higher in rectal biopsy samples from IBS-D patients than those from normal controls (0.86 +/- 0.18 and 0.28 +/- 0.04 mU/mg protein, P < 0.05). Mucosal mast cell counts were not significantly different between the 2 groups (P > 0.05). However, correlation analysis revealed that only mucosal mast cell count was significantly correlated with intestinal permeability in IBS-D patients (r = 0.558, P < 0.05). CONCLUSIONS: This study demonstrated a positive correlation between the number of mucosal mast cells and intestinal permeability, suggesting that mucosal mast cells play an important role for increased intestinal permeability in patients with IBS-D.
Biopsy
;
Diarrhea
;
Horseradish Peroxidase
;
Humans
;
Irritable Bowel Syndrome
;
Mast Cells
;
Permeability
;
Tryptases
8.Application of an Insulin Analogue in Six Hypoglycemia-Prone Hemodialysis Patients with Type 2 Diabetes.
Gyung Eun KIM ; Seong Bin HONG ; Ju Young HAN ; Ji Hun JANG ; Dong Hyuk YANG ; Seoung Woo LEE ; Joon Ho SONG
Korean Journal of Medicine 2012;83(5):647-653
Day-to-day insulin requirements often change due to subtle variations in insulin metabolism in patients with type 2 diabetes undergoing hemodialysis. In such cases, intra-hemodialysis hypoglycemia frequently occurs and is a main factor interfering with the delivery of dialysis. As a result, it reduces the quality of life in patients undergoing hemodialysis. The long-acting insulin analogue glargine provides peakless, continuous release over 24 h that approximates a normal basal insulin pattern. Because it has no peak, its use in patients with diabetes undergoing hemodialysis would hypothetically be useful. Specifically, patients would be able to avoid intra-hemodialysis hypoglycemia without the necessity of skipping insulin administration on the day of hemodialysis and achieving adequate glucose control on other days. We recently experienced six cases that switched from treatment with intermediate-acting insulin to a long-acting insulin analogue, which provided better glycemic control by reducing hypoglycemia risk. Limited data are available in the literature concerning insulin analogue usage in patients with diabetes undergoing hemodialysis. Our experience suggests a large-scale prospective investigation is required on this issue.
Dialysis
;
Glucose
;
Humans
;
Hypoglycemia
;
Insulin
;
Insulin, Long-Acting
;
Kidney Failure, Chronic
;
Quality of Life
;
Renal Dialysis
;
Insulin Glargine
9.Correlation between Frailty Level and Adverse Health-related Outcomes of Community-Dwelling Elderly, One Year Retrospective Study.
Eun Young SHIM ; Seung Hyun MA ; Sun Hyoung HONG ; Yun Sang LEE ; Woo Youl PAIK ; Deok Seoung SEO ; Eun Young YOO ; Mee Young KIM ; Jong Lull YOON
Korean Journal of Family Medicine 2011;32(4):249-256
BACKGROUND: Frailty is considered to be a clinical syndrome characterized by decreased physiological reserves associated with a greater risk of health-related problems, hospitalization, and death. The current study examined hospitalization, falls, cognitive decline and disability between robust, prefrail and frail elderly in one year. METHODS: 110 participants aged 65 or more who visited two senior welfare centers in Seoul from February 2008 to June 2008 were surveyed again from March 2009 to June 2009 with demographic characteristics, number of chronic diseases and medication, study of osteoporotic fractures (SOF) frailty index, instrumental activity of daily living (IADL), depression, mini-mental state examination-Korean version (MMSE-K), falling history and admission history within one year. These results were compared with participants' previous survey done one year ago. RESULTS: Among total 110 subjects, 48 (44%) robust, 30 (27%) prefrail, and 32 (29%) frail subjects changed to 26 (24%), 54 (49%), and 30 (27%) respectively over the year. There were statistical significances in age, number of chronic disease, depressive mood, MMSE, falls, hospitalization, IADL disability contributing to frailty (P < 0.05). Frailty defined by SOF frailty index was associated with greater risk of adverse outcomes. Frail subjects had a higher age-adjusted risk of cognitive function decline (odds ratio [OR], 3.57), disability (OR, 9.64), fall (OR, 5.42), and hospitalization (OR, 4.45; P < 0.005). CONCLUSION: The frailty index like SOF frailty index might predict risk of falls, disability, hospitalization, and cognitive decline in the elderly, emphasizing special attention to the individuals showing frailty in outpatient examination.
Aged
;
Chronic Disease
;
Depression
;
Frail Elderly
;
Hospitalization
;
Humans
;
Osteoporotic Fractures
;
Outpatients
;
Retrospective Studies
10.Characteristics and Management of Residual or Slowly Recurred Intracranial Aneurysms.
Eun Hyun IHM ; Chang Ki HONG ; Yu Shik SHIM ; Jin Young JUNG ; Jin Yang JOO ; Seoung Woo PARK
Journal of Korean Neurosurgical Society 2010;48(4):330-334
OBJECTIVE: Residual aneurysm from incomplete clipping or slowly recurrent aneurysm is associated with high risk of subarachnoid hemorrhage. We describe complete treatment of the lesions by surgical clipping or endovascular treatment. METHODS: We analyzed 11 patients of residual or recurrent aneurysms who had undergone surgical clipping from 1998 to 2009. Among them, 5 cases were initially clipped at our hospital. The others were referred from other hospitals after clipping. The radiologic and medical records were retrospectively analyzed. RESULTS: All patients presented with subarachnoid hemorrhage at first time, and the most frequent location of the ruptured residual or recurrent aneurysm was in the anterior communicating artery to posterior-superior direction. Distal anterior cerebral artery, posterior communicating artery, and middle cerebral artery was followed. Repositioning of clipping in eleven cases, and one endovascular treatment were performed. No residual aneurysm was found in postoperative angiography, and no complication was noted in related to the operations. CONCLUSION: These results indicate the importance of postoperative or follow up angiography and that reoperation of residual or slowly recurrent aneurysm should be tried if such lesions being found. Precise evaluation and appropriate planning including endovascular treatment should be performed for complete obliteration of the residual or recurrent aneurysm.
Aneurysm
;
Angiography
;
Anterior Cerebral Artery
;
Arteries
;
Follow-Up Studies
;
Humans
;
Intracranial Aneurysm
;
Medical Records
;
Middle Cerebral Artery
;
Reoperation
;
Retrospective Studies
;
Subarachnoid Hemorrhage
;
Surgical Instruments

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