• The Journal of Korean Academy of Prosthodontics
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• v.43 no.6
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• pp.751-763
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• 2005

Statement of problem. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. The surface quality of the implant depends on the chemical, physical, mechanical and topographical properties of the surface. The different properties will interact with each other and a change in thickness of the oxide layer may also result in a change in surface energy, the surface topography and surface, chemical composition. However, there is limited the comprehensive study with regard to changed surface and biologic behavior of osteoblast by anodization. Purpose of study. The aim of this study was to analyze the characteristics of an oxide layer formed and to evaluate the cellular biologic behaviors on titanium by anodic oxidation (anodization) by cellular proliferation, differentiation, ECM formation and gene expression. And the phospholipase activity was measured on the anodized surface as preliminary study to understand how surface properties of Ti implant are transduced into downstream cellular events. Methods and Materials. The surface of a commercially pure titanium(Grade 2) was modified by anodic oxidation. The group 1 samples had a machined surface and other three experimental specimens were anodized under a constant voltage of 270 V(Group 2), 350 V(Group 3), and 450 V(Group 4). The specimen characteristics were inspected using the following five categories; the surface morphology, the surface roughness, the thickness of oxide layer, the crystallinity, and the chemical composition of the oxide layer. Cell numbers were taken as a marker for cell proliferation. While the expression of alkaline phosphatase and Runx2 (Cbfa1) was used as early differentiation marker for osteoblast. The type I collagen production was determined, which constitutes the main structural protein of the extracellular matrix. Phospholipase $A_2$ and D activity were detected. Results. (1) The anodized titanium had a porous oxide layer, and there was increase in both the size and number of pores with increasing anodizing voltage. (2) With increasing voltage, the surface roughness and thickness of the oxide film increased significantly (p<0.01), the $TiO_2$phase changed from anatase to rutile. During the anodic oxidization, Ca and P ions were more incorporated into the oxide layer. (3) The in vitro cell responses of the specimen were also dependant on the oxidation conditions. With increasing voltage, the ALP activity, type I collagen production, and Cbfa 1 gene expression increased significantly (p<0.01), while the cell proliferation decreased. (4) In preliminary study on the relation of surface property and phospholipase, PLD activity was increased but $PLA_2$ activity did not changed according to applied voltage. Conclusion. The anodized titanium shows improved surface characteristics than the machined titanium. The surface properties acquired by anodization appear to give rise more mature osteoblast characteristics and might result in increased bone growth, and contribute to the achievement of a tight fixation. The precise mechanism of surface property signaling is not known, may be related to phospholipase D.

• Korean Journal of Cleft Lip And Palate
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• v.8 no.2
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• pp.71-79
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• 2005

Purpose: Maxillary hypoplasia is a common developmental problem of cleft lip and palate. Fair results with distraction osteogenesis have been reported especially when these patients need a large amount of maxillary advancement, instead of orthognathic surgery. The purpose of this study is to evaluate the clinical results with a relatively new distractor, $TS-MD^{(R)}$ (Trans-sinusoidal maxillary distractor, KLS Martin, Tuttlingen, Germany) which was used for the advancement of the maxilla in the cleft patients. Patients and Method: Distraction osteogenesis using $TS-MD^{(R)}$ was performed for four CLP patients (three males and one female) who had maxillary hypoplasia. All patients were over 16 years old. As three patients showed mandibular prognathism as well, bilateral sagittal split ramus osteotomy for mandibular setback was performed at the same time. After consolidation periods of 4 to 12 weeks, the distraction devices were removed and miniplates were placed for simultaneous internal fixation. Results: Three patients showed a large amount of incisal overbite but one patient did not have sufficient maxillary advancement. Le Fort I osteotomy, maxillary advancement and internal fixation should have been performed for the patient when removing the distraction devices. Different from the $clinician{\box}s$ expectation, the amount of maxillary advancement using $TS-MD^{(R)}$ was not sufficient, although the device has rigid mechanical property. Rotation of maxilla during distraction forward and downward was also observed. Conclusion: Even though the maxillary advancement with $TS-MD^{(R)}$ device could be achieved, the clinical control of some characteristics related with the device was necessary. More clinical studies on $TS-MD^{(R)}$ should be performed.

• Archives of Plastic Surgery
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• v.46 no.4
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• pp.336-343
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• 2019

Background Sternal rigid plate fixation (RPF) has been adopted in recent years in high-risk cases to reduce complications associated with steel wire cerclage, the traditional approach to sternal closure. While sternal RPF has been associated with lower complication rates than wire cerclage, it has its own complication profile that requires evaluation, necessitating a critical examination from a national perspective. This study will report the outcomes and associated risk factors of sternal RPF using a national database. Methods Patients undergoing sternal RPF from 2005 to 2016 in the American College of Surgeons-National Surgical Quality Improvement Program were identified. Demographics, perioperative information, and complication rates were reviewed. Logistic regression analysis was performed to identify risk factors for postoperative complications. Results There were 381 patient cases of RPF identified. The most common complications included bleeding (28.9%), mechanical ventilation >48 hours (16.5%), and reoperation/readmission (15.2%). Top risk factors for complications included dyspnea (odds ratio [OR], 2.672; P<0.001), nonelective procedure (OR, 2.164; P=0.010), congestive heart failure (OR, 2.152; P=0.048), open wound (OR, 1.977; P=0.024), and operating time (OR, 1.005; P<0.001). Conclusions Sternal RPF is associated with increased rates of three primary complications: blood loss requiring transfusion, ventilation >48 hours, and reoperation/readmission, each of which affected over 15% of the study population. Smokers remain at an increased risk for surgical site infection and sternal dehiscence despite RPF's purported benefit to minimize these outcomes. Complications of primary versus delayed sternal RPF are roughly equivalent, but individual patients may perform better with one versus the other based on identified risk factors.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.6
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• pp.491-497
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• 2001

Polymethylmethacrylate(PMMA) is currently commonly used material for the reconstruction of bone defects and fixation of joint prosthetics following congenital and acquired causes. Although PMMA has widespread use, it does not possess the ideal mechanical characteristics with osteoconductivity and osteoinductivity required. In order to overcome these problem, addition of bovine bone drived defatting demineralized bone(BDB) powders to a PMMA bone cement was done for improvement of physical property and bone forming characteristics of composite. In order to investigate the influence of BDB reinforcement on the PMMA, we measured physical property of compressive, tensile, flexural strength, and scanning electron microscopic examinations. The results were obtained as follows: 1. The PMMA forms a solid cellular matrix with open cells about $100{\mu}m$ in variable size and incorporating BDB. BDB aggregates inside the cells form a porous network that is accessible from the outer surface. 2. The physical properties were compressive strength of mean $22.74{\pm}1.69MPa$, tensile strength of mean $22.74{\pm}1.69MPa$, flexural strength of mean $77.53{\pm}6.93MPa$. Scanning electron microscopic examinations were revealed that there was DBD particles form a highly porous agglomerates. BDB can be added PMMA in the form of dried powders, the composites are applicable as bone substitutes. BDB and PMMA mixture is shown to produce a class of composites that due to their microstructure and improved mechanical properties may be suitable for application as bone subsitutes. The mechanical and material properties of the BDB-PMMA bone substitute composites are competitive with those properties of a porous ceramic matrix of other hydroxyapatite and with those of natural bones.

• Journal of Chest Surgery
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• v.43 no.3
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• pp.235-245
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• 2010

Background: Our goal was to evaluate anti-calcification effects of decellularization and diverse fixing methods including preincubation of the bovine pericardium with ethanol. We also assessed changes in mechanical properties. Material and Method: Harvested bovine pericardium was decellularized with 0.25% sodim dodecysulfate and then treated with 5 methods of fixation: (1) 0.5% glutaraldehyde (GA) for 14 days, (2) 0.5% GA for 5 days, 2% GA for 2 days and 0.25% GA for 7 days, (3) 0.5% GA for 5 days, 2% GA for 2 days, 0.25% GA for 7 days, and then 70% ethanol for 2 days, (4) 0.5% GA for 5 days, a mixture of 2% GA and 70% ethanol for 2 days, and 0.25% GA for 7 days, (5) 0.5% GA for 5 days, a mixture of 2% GA, 65% ethanol, and 5% octanediol for 2 days and then 0.25% GA for 7 days. All treated bovine pericardia were tested for histological variables, lipid content, and mechanical properties including tensile strength and thermal stability. A total 10 kinds of differently treated bovine pericardia were implanted into rat subdermis and harvested 8 weeks later. Harvested pericardia were evaluated for calcium content. Result: No protein denaturation was observed microscopically after decellularization. There was a 32% mean decrease in tensile strength index after decellularization in the bovine pericardium group fixed. Octanediol preincubation attenuated the decrease in tensile strength and maintained thermal stability. TG and cholesterol were not affected by decellularization but were decreased by organic solvent. Calcium content was decreased after decellularization, and organic solvent preincubation decreased calcification in the non-decellularized bovine pericardium group. Conclusion: Decellularization and organic solvent preincubation have anti-calcification effects but decellularization may cause mechanical instability. A method of decellularization and fixation that does not cause damage to matrices will be needed for evaluation of the next step in using tissue-engineering for replacement of cardiac valves.

• Journal of Chest Surgery
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• v.42 no.5
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• pp.566-575
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• 2009

Background: The function of a bioprosthetic heart valve is determined largely by the material properties of the valve cusps. The uniaxial tensile test has been studied extensively. This type of testing, however, does not replicate the natural biaxial loading condition. The objective of the present study was to investigate the regional variability of the biaxial strain versus pressure relationship based on the types of fixation liquid models. Material and Method: Porcine aortic valves and pulmonary valves were assigned to three groups: the untreated fresh group, the fixed with glutaraldehyde (GA) group, and the glutaraldehyde with solvent (e.g., ethanol) group. For each group we measured the radial and circumferential stretch characteristics of the valve as a function of pressure change. Result: Radial direction elasticity of porcine aortic and pulmonary valves were better than circumferential direction elasticity in fresh, GA fixed and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of pulmonary valves were better than aortic valves in GA fixed, and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of aortic valves were decreased after GA and GA+solvent fixation(p=0.00), except for circumferential elasticity of GA+solvent fixed valves (p=0.785). The radial (p=0.137) and circumferential (p=0.785) direction of elasticity of aortic valves were not significantly different between GA fixed. and GA+solvent fixed groups. Radial (p=0.910) and circumferential (p=0.718) direction of elasticity of pulmonary valve also showed no significant difference between GA fixed and GA+solvent fixed groups. Conclusion: When fixing porcine valves with GA, adding a solvent does not cause a loss of mechanical properties, but, does not improve elasticity either. Radial direction elasticity of porcine aortic and pulmonary valves was better than circumferential direction elasticity.

• Journal of Chest Surgery
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• v.41 no.3
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• pp.295-304
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• 2008

Background: Various experimental trials for the development of bioprosthetic devices are actively underway, secondary to the limited supply of autologous and homograft tissue to treat cardiac diseases. In this study, porcine bioprostheses that were treated with glutaraldehyde (GA), ethanol, or sodium dodecylsulfate (SDS) were examined with light microscopy and transmission electron microscopy for mechanical and physical imperfections before implantation, Material and Method: 1) Porcine pericardium, aortic valve, and pulmonary valve were examined using light microscopy and JEM-100CX II transmission electron microscopy, then compared with human pericardium and commercially produced heterografts. 2) Sections from six treated groups (GA-Ethanol, Ethanol-GA, SDS only, SDS-GA, Ethanol-SDS-GA and SDS-Ethanol-GA) were observed using the same methods. Result: 1) Porcine pericardium was composed of a serosal layer, fibrosa, and epicardial connective tissue. Treatment with GA, ethanol, or SDS had little influence on the collagen skeleton of porcine pericardium, except in the case of SDS pre-treatment. There was no alteration in the collagen skeleton of the porcine pericardium compared to commercially produced heterografts. 2) Porcine aortic valve was composed of lamina fibrosa, lamina spongiosa, and lamina ventricularis. Treatment with GA, ethanol, or SDS had little influence on these three layers and the collagen skeleton of porcine aortic valve, except in the case of SDS pre-treatment. There were no alterations in the three layers or the collagen. skeleton of porcine aortic valve compared to commercially produced heterografts. Conclusion: There was little physical and mechanical damage incurred in porcine bioprosthesis structures during various glutaraldehyde fixation processes combined with anti-calcification or decellularization treatments. However, SDS treatment preceding GA fixation changed the collagen fibers into a slightly condensed form, which degraded during transmission electron micrograph. The optimal methods and conditions for sodium dodecylsulfate (SDS) treatment need to be modified.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.244.1-244.1
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• 2010

Bio energy development by using Low Calorific Gas Turbine(LCGT) has been developed for New & Renewable energy source for next generation power system, low fuel and operating cost method by using the renewable energy source in landfill gas (LFG), Food Waste, water waste and Livestock biogas. Low calorific fuel purification by pretreatment system and carbon dioxide fixation by green house system are very important design target for evaluate optimum applications for bio energy. Main problems and accidents of Low Calorific Gas Turbine system was derived from bio fuel condition such as hydro sulfide concentration, siloxane level, moisture concentration and so on. Even if the quality of the bio fuel is not better than natural gas, LCGT system has the various fuel range and environmental friendly power system. The mechanical characterisitics of LCGT system is a high total efficiency (>70%), wide range of output power (30kW - 30MW class) and very clean emmission from power system (low NOx). Also, we can use co-generation system. A green house designed for four different carbon dioxide concentration from ambient air to 2000 ppm by utilizing the exhaust gas and hot water from LCGT system. We look forward to contribute the policy for Renewable Portfolio Standards(RPS) by using LCGT power system.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.77-81
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• 2008

The goal of rotator cuff repairs is to achieve high initial fixation strength, minimize gap formation, maintain mechanical stability under cyclic loading and optimize the biology of the tendon-bone interface until the cuff heals biologically to the bone. Single row repairs are least successful in restoring the footprint of the rotator cuff and are most susceptible to gap formation. Double row repairs have an improved load to failure and minimal gap formation. Transosseous equivalent repairs (suture bridge technique) have the highest ultimate load and resistance to shear and rotational forces and the lowest gap formation. Even though the superior advantages of double row and transosseous equivalent repairs, those techniques take longer surgical time and are more expensive than single row repairs. Therefore single row repairs can be useful in bursal side partial thickness or small size full thickess rotator cuff tear.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.82-89
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• 2008

Ideal rotator cuff repair is to maintain high fixation strength and minimize gap formation for optimizing the environment of biologic healing of tendon to bone. Among the current repair techniques, the suture bridge technique is superior to single- or double-row repair in ultimate load to failure, gap formation, restoring anatomical footprint and achieving pressurized contact area. The suture bridge technique also minimizes gap formation and has rotational and torsional resistances allowing early rehabilitation. However, despite superior biomechanical characteristics of the suture bridge technique, there is no evidence that these mechanical advantages result in better clinical outcomes. Furthermore, there is no difference in failure rates between the double-row repair and suture bridge techniques. An appropriate repair technique should be determined based on tear size and pattern and tendon quality.