1.A Study on Noise Induced Hearing Loss of Employees Working for Seoul Metropolitan Subway Cooperation.
Seoung ho RYU ; Young Jun KWON ; Soo Jin LEE ; Jae Choel SONG
Korean Journal of Aerospace and Environmental Medicine 2001;11(1):37-44
Although some employees working for Seoul Metropolitan Subway Cooperation are working at the noisy workplaces, they has been excluded from Special Periodic Health Examination Program. And some workers complained of hearing loss or tinnitus. So, this study was carried out to investigate the prevalence rate of Noise Induced Hearing Loss of employees(10,792) working for Seoul Metropolitan Subway Cooperation. The number of subjects were total 10,792 with 10,355 men and 437 women. A questionnaire survey, otological examination, Rinne test, pure tone audiometric tests were performed and through the first and second screening audiometric examination, 605 workers were selected after excluding employees with past otologic problems, recent exposure to high level noise, and under medications. and the results were as follow; 1. Among 10,792 workers, 4 workers(0.037%) diagnosed as NIHL and 601 workers(5.56%) as early NIHL. As workers grew older, the prevalence rate of NIHL and early NIHL became more rising. 2. The prevalence rate of NIHL and early NIHL was different between work site. After age adjustment, The prevalence rate of NIHL and early NIHL was 23.74% in Train repairmen{80dB(A)}, 3.1% in Station staffs{below 70dB(A)}, 2.53% in Train crew{below 70dB(A)}, 2.1% in Office workers. 3. The perception rate of necessities of ear plug in NIHL and early NIHL was below 55% and wearing rate of ear plug in NIHL and early NIHL was 1.1% In conclusion, some employees who was under working environment in Seoul Metropolitan Subway Cooperation should be monitored to prevent hearing impairment and would be needed health education.
Ear
;
Female
;
Health Education
;
Hearing Loss*
;
Hearing*
;
Humans
;
Male
;
Mass Screening
;
Noise*
;
Prevalence
;
Railroads*
;
Seoul*
;
Tinnitus
;
Workplace
;
Surveys and Questionnaires
2.Minimal Medial-row Tie with Suture-bridge Technique for Medium to Large Rotator Cuff Tears.
Hyun Il LEE ; Ho Young RYU ; Sang Jun SHIM ; Jae Chul YOO
Clinics in Shoulder and Elbow 2015;18(4):197-205
BACKGROUND: The purpose of this study was to evaluate the postoperative magnetic resonance imaging (MRI) results of minimal-tying (one medial-row tie among 4 medial-row sutures) on the medial-row in double-row suture-bridge configuration (2x2 anchor with 4x4 suture stands). METHODS: From 2011 March to 2012 July, 79 patients underwent arthroscopic rotator cuff repair using 2x2 anchor double-row configuration. The mean age was 61.3 years (range, 31-81 years). Two double-loaded suture anchors were used for medial-row. Four medialrow stitches were made with only one medial-row knot-tying (the most anterior suture). Lateral-row was secured using the conventional suture-bridge anchor technique; all 4 strands were used for each anchor. Repair integrity was evaluated with MRI at mean 6.2 months postoperatively. Retear and the pattern of retear, change of fatty infiltration, and muscle atrophy of supraspinatus were evaluated using pre- and postoperative MRI. RESULTS: Repaired tendon integrity was 38 for type I, 30 for type II, 6 for type III, 4 for type IV, and 1 for type V, according to Sugaya classification. Considering type IV/V as retear, the rate was 6.3% (5 out of 79 patients). Medial cuff failure was observed in 4 patients. Fatty atrophy of supraspinatus was significantly improved postoperatively according to Goutallier grading (p=0.01). The level of muscle atrophy of supraspinatus was not changed significantly after surgery. CONCLUSIONS: Minimal tying technique with suture configuration of four-by-four strand double-row suture-bridge yielded a lower retear rate (6.3%) in medium to large rotator cuff tears.
Arthroscopy
;
Atrophy
;
Classification
;
Humans
;
Magnetic Resonance Imaging
;
Muscular Atrophy
;
Rotator Cuff*
;
Shoulder
;
Suture Anchors
;
Sutures
;
Tears*
;
Tendons
3.Oral rehabilitation of a patient with severely worn dentition using monolithic zirconia.
The Journal of Korean Academy of Prosthodontics 2016;54(3):273-279
Severe tooth wear may lead to pathological changes of pulp, imbalance in occlusion as well as functional and esthetic problems. In this case, 34-year-old male came to the hospital because of generally worn dentition due to attrition and erosion. After evaluation, a full mouth restoration with elevation of the vertical dimension of occlusion was planned. After occlusion was stabilized by an occlusal stabilization appliance, centric relation position was recorded and subsequent provisional restorations were fabricated. After evaluation, a CAD-CAM (computer aided design-computer aided manufacturing) prosthetic restoration was carried out using monolithic zirconia. After 12 months of follow up observation, the patient was satisfied with function and esthetic appearance.
Adult
;
Bruxism
;
Centric Relation
;
Computer-Aided Design
;
Dentition*
;
Follow-Up Studies
;
Humans
;
Male
;
Mouth
;
Rehabilitation*
;
Tooth Wear
;
Vertical Dimension
4.Pre-contoured reconstruction plate fabricated via three-dimensional printed bending support
In-Seok SONG ; Jae-Jun RYU ; Young-Jun CHOI ; Ui-Lyong LEE
Journal of the Korean Association of Oral and Maxillofacial Surgeons 2021;47(3):233-236
A mandibular continuity defect can be repaired using either a prosthetic device or autogenous bone. A titanium reconstruction plate can be used with a localized or vascularized flap over the defect of the mandible. Unfortunately, the plate may fail due to plate exposure, screw loosening, fracture, or infection, and will need to be removed. Plate exposure though the skin or mucosa is one of the main reasons for failure. In the present work, the authors introduced a lingually positioned reconstruction plate fabricated via three-dimensional printed bending support. This custom reconstruction plate can avoid plate re-exposure as well as reduce surgical errors and operation time.
5.Pre-contoured reconstruction plate fabricated via three-dimensional printed bending support
In-Seok SONG ; Jae-Jun RYU ; Young-Jun CHOI ; Ui-Lyong LEE
Journal of the Korean Association of Oral and Maxillofacial Surgeons 2021;47(3):233-236
A mandibular continuity defect can be repaired using either a prosthetic device or autogenous bone. A titanium reconstruction plate can be used with a localized or vascularized flap over the defect of the mandible. Unfortunately, the plate may fail due to plate exposure, screw loosening, fracture, or infection, and will need to be removed. Plate exposure though the skin or mucosa is one of the main reasons for failure. In the present work, the authors introduced a lingually positioned reconstruction plate fabricated via three-dimensional printed bending support. This custom reconstruction plate can avoid plate re-exposure as well as reduce surgical errors and operation time.
6.The Effect of Three Surface Sealants on Microleakage of Class V Composite Resin Restorations.
The Journal of Korean Academy of Prosthodontics 2009;47(2):182-190
STATEMENT OF PROBLEM: Microleakage at the occlusal and gingival margin of Class V cavities restored with composite resin has traditionally been considered an obstacle to successful restoration. PURPOSE: The aim of this study was to assess the effectiveness of three different surface sealants(Fortify, Permaseal and Biscover LV) on the marginal sealing of Class V light-activated composite resin restorations(Z250). MATERIAL AND METHODS: Forty noncarious human premolars and molars extracted within a three-month period were selected. Class V cavities with the occlusal margin in enamel and gingival margin in cementum were prepared in both buccal and lingual surfaces. The teeth, randomly assigned in four groups with twenty cavities in each group, were restored with composite resin after applying an adhesive system(Clearfil SE bond). After the finishing and polishing procedures, the restorations were covered with a specific surface sealants, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled, and immersed in a 2% methylene blue solution for twenty four hours and sectioned longitudinally. The marginal microleakage was evaluated at the occlusal and gingival interfaces using a microscope and compared among the four groups using ANOVA test and Wilcoxon Rank-Sum test(alpha=0.05). RESULTS: Statistical analysis showed that there was significantly less leakage when the surface sealants were used than there was in control group (P < .05). There were no significant differences of microleakage at occlusal and gingival margins among groups. There were no significant differences between microleakage of occlusal and gingival margins in each group. Fortify was not statistically different from control group at the gingival margin (P > .05). CONCLUSION: Application of surface sealants was an effective method of surface coating in reducing microleakage at occlusal and gingival margins of Class V composite resin restorations. However, it is certain that some microleakage still occurred despite the application of surface sealants, especially gingival margins.
Acrylates
;
Adhesives
;
Bicuspid
;
Dental Cementum
;
Dental Enamel
;
Humans
;
Methylene Blue
;
Molar
;
Resin Cements
;
Tooth
7.Endovascular Treatment of "Kissing Aneurysms" at the Anterior Communicating Artery.
Sang Jun SUH ; Dong Gee KANG ; Kee Young RYU ; Jae Hoon CHO
Journal of Korean Neurosurgical Society 2008;44(3):163-165
Kissing aneurysms are the rare type of multiple aneurysms. They are adjacent aneurysms of different origin arteries in the same region, which require great care in diagnosis and treatment. We report a case of kissing aneurysms at the anterior communicating artery (AcomA) which were treated by endovascular coil embolization.
Aneurysm
;
Arteries
;
Subarachnoid Hemorrhage
8.Effects of activators contained in adhesives on dentin bond strengths.
Hye Kyung KANG ; Joo Hee SHIN ; Kyu Won SUH ; Jae Jun RYU
The Journal of Korean Academy of Prosthodontics 2008;46(5):511-519
STATEMENT OF PROBLEM: An incompatibility between the initiator systems of self-curing composite resins and light-curing adhesives was supposed recently. PURPOSE: The purpose of the study was to evaluate the influence of activators for self/dual bonding on dentin shear bonding strengths. MATERIAL AND METHODS: Fifty human molars were divided into 5 groups. A flat dentin surface was created for each tooth. A self-curing composite resin (Luxacore) was bonded with the following adhesives (n = 10): One-Step, Prime and Bond NT, AdheSE, Prime and Bond NT and AdheSe were also used in combination with activators. Shear bond strengths were measured after 24 hours of water storage. The specimens were loaded in shear in the Instron until failure at a 1 mm/min crosshead speed. Data were compared using one-way ANOVA and Tukey HSD test (alpha = 0.05). RESULTS: The dentin adhesive systems in order of decreasing median bond strength were One-Step > Prime & Bond NT with activator, AdheSe with activator > Prime and Bond NT, AdheSe. Among adhesives, One-Step had the highest bond strength. Prime & Bond NT with activator had higher bond strengths than Prime and Bond NT that was used alone, and so was AdheSe. CONCLUSION: Shear bond strengths were increased in Prime and Bond NT and AdheSe when these were used with activators comparing used without activators. But using activators was not effective clinically comparing One-Step.
Adhesives
;
Composite Resins
;
Dentin
;
Humans
;
Molar
;
Polymethacrylic Acids
;
Tooth
;
Water
9.Removal torque of bicortically stabilized RBM(resorbable blast media) pin implants in rabbit tibia.
Kwon Sik KIM ; Kyu Won SUH ; Richard sungbok LEE ; Jae Jun RYU
The Journal of Korean Academy of Prosthodontics 2006;44(6):722-733
STATEMENT OF PROBLEM: The use of small diameter implants having less than 3 mm in diameter were restricted because of lack of bonding strength to bone. PURPOSE: The purpose of this study was to observe how much resorbable blast media pin implants increase the binding force to the bone compared to machined transitional pin implants by measuring removal torque, and whether they can be used as final implants for replacement of small diameter teeth. MATERIAL AND METHOD: Fifteen rabbits were used in this study. Two kinds of implants (resorbable blast media pin implants and machined transitional pin implants) were inserted in each tibia bicortically. After healing time of 2, 4 and 8 weeks, the removal torque values were recorded and the rabbits were sacrificed for histological analysis. Linear finite element method analyses were conducted to compare bicortical fixation with monocortical fixation. RESULT AND CONCLUSION: Within the limitation of this in vivo study, the following conclusions were drawn: 1) The removal torque value of RBM pin implants showed statistically significant increase compared to machined pin implants at 2, 4, and 8 weeks respectively (p<0.05). 2) The removal torque value of RBM pin implants at 2, 4, and 8 weeks was increased statistically significantly with time (p<0.05). 3) Bicortical fixation showed better stress distribution compared with monocortical fixation in a linear finite element method analysis. 4) RBM pin implants are not recommended as transitional implants because they showed a lot of bone fracture in histologic specimens.
Fractures, Bone
;
Rabbits
;
Tibia*
;
Tooth
;
Torque*
10.A Case of Potter Syndrome Type I.
Jong Cheol RYU ; Jae Kwang HONG ; Jun Taek PARK ; Jung Sik MIN ; Chang Jee CHOI ; Je Geun CHI
Journal of the Korean Pediatric Society 1986;29(10):104-108
No abstract available.