• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.169-181
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• 2007

Statement of problem: Titanium is well known as a proper metal for the dental restorations, because it has an excellent biocompatibility, resistance to corrosion, and mechanical property. However, adhesion between titanium and dental porcelains is related to the diffusion of oxygen to the reaction layers formed on cast-titanium surfaces during porcelain firing and those oxidized layers make the adhesion difficult to be formed. Many studies using mechanical, chemical and physical methods to enhance the titanium-ceramic adhesion have been actively performed. Purpose: This study meant to comparatively analyse the adhesion characteristics depending on different titanium surface coatings after coating the casts and wrought titanium surfaces with Au and TiN. Material and method: In this study, the titanium specimens (CP-Ti, Grade 2, Kobe still Co. Japan) were categorized into cast and wrought titanium. The wrought titanium was cast by using the MgO-based investment(Selevest CB, Selec). The cast and wrought titanium were treated with Au coating($ParaOne^{(R)}$., Gold Ion Sputter, Model PS-1200) and TiN coating(ATEC system, Korea) and the ultra low fusing dental porcelain was fused and fired onto the samples. Biaxial flection test was done on the fired samples and the porcelain was separated. The adhesion characteristics of porcelain and titanium after firing and the specimen surfaces before and after the porcelain fracture test were observed with SEM. The atomic percent of Si on all sample surfaces was comparatively analysed by EDS. In addition, the constituents of specimen surface layers after the porcelain fracture and the formed compound were evaluated by X-ray diffraction diagnosis. Result: The results of this study were obtained as follows : 1. The surface characteristics of cast and wrought titanium after surface treatment(Au, TiN, $Al_2O_3$ sandblasting) were similar and each cast and wrought titanium showed similar bonding characteristics. 2. Before and after the biaxial flection test, the highest atomic weight change of Si component was found in $Al_2O_3$ sandblasted wrought titanium(28.6at.% $\rightarrow$ 8.3at.%). On the other hand, the least change was seen in Au-Pd-In alloy(24.5at.% $\rightarrow$ 9.1at.%). 3. Much amount of Si components was uniformly distributed in Au and TiN coated titanium, but less amount of Si's was unevenly dispersed on Al2O3 sandblasting surfaces. 4. In X-ray diffraction diagnosis after porcelain debonding, we could see $Au_2Ti$ compound and TiN coating layers on Au and TiN coated surfaces and $TiO_2$, typical oxide of titanium, on all titanium surfaces. 5. Debonding of porcelain on cast and wrought titanium surface after the biaxial flection is considered as a result of adhesion deterioration between coating layers and titanium surfaces. We found that there are both adhesive failure and cohesive failure at the same time. Conclusion: These results showed that the titanium-ceramic adhesion could be improved by coating cast and wrought titanium surfaces with Au and TiN when making porcelain fused to metal crowns. In order to use porcelain fused to titanium clinically, it is considered that coating technique to enhance the bonding strength between coating kKlayers and titanium surfaces should be developed first.

• Pediatric Infection and Vaccine
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• v.23 no.1
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• pp.31-39
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• 2016

Purpose: The aim of this study was to investigate the prognostic factors for Pneumocystis jirovecii pneumonia (PCP) and to evaluate the influence of PCP prophylaxis in pediatric patients. Methods: From January 2002 to April 2015, patients aged <18 years with a diagnosis of confirmed PCP at our institute were reviewed retrospectively. Clinical characteristics and outcomes were compared according to the groups with or without PCP prophylaxis. Risk factors associated with PCP-related death were analyzed by logistic regression analysis. Results: During study period, a total of 24 patients were diagnosed with PCP by immunofluorescence assay and/or PCR. The median age of the patients was 5 years (range, 3 months-18 years) and 23 (96%) had immunocompromised conditions including hematologic disorders with or without hematopoietic stem cell transplantation (n=15), solid organ transplantation (n=4), and primary immune deficiency (n=4). Most common presenting symptoms were tachypnea and cough (92%, each). At the time of diagnosis, 79% (19/24) and 25% (6/24) suffered from respiratory failure and multi-organ dysfunction syndrome (MODS), respectively. Mechanical ventilation was required in 8 (33%) patients and 5 (21%) patients died of PCP. Multivariate analysis showed that MODS at initial presentation was an indicator of poor prognosis (OR, 17.1 [95% CI 1.13-257.67]; P=0.04). Compared to the patients without PCP prophylaxis, the frequency of MODS at diagnosis, need for mechanical ventilation and length of hospital days were significantly less common in the children who received PCP prophylaxis. Conclusions: MODS at presentation was a significant predictor for poor outcome and PCP prophylaxis could alleviate the clinical courses of pediatric PCP. Prospective study will be mandatory to determine the risk factors for development and deterioration of PCP in children.

• Journal of Chest Surgery
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• v.39 no.7 s.264
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• pp.527-533
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• 2006

Background: A retrospective study was conducted to analyze the results of St. Jude Medical mitral valve replacement at the Chonbuk National University Hospital since the initial implant in May 1984. Material and Method: Between May of 1984 and December of 1996, 95 patients underwent MVR with the St. Jude Medical mechanical valve prosthesis at Department of Medical Science of Chonbuk National University Hospital and follow-up ended in May of 2004. Result: Age ranged from 19 to 69 years. Follow-up (mean${\pm}$standard deviation) averaged $10.6{\pm}4.2\;year$. Thirty-day operative mortality was 4.2% (4/95). Nine late deaths have occurred and actuarial survival was $90.5{\pm}3.0%,\;87.9{\pm}3.4%\;and\;83.2{\pm}4.6%$ at 5, 10 and 20 years, respectively. Probability of freedom from valve-rotated death was $95.5{\pm}2.1%,\;94.3{\pm}2.4%\;and\;91.0{\pm}3.9%$ at 5, 10 and 20 years, respectively. Seven patients have sustained thromboembolic events (1,05%/patient-year). Fifteen patients had anticoagulation related hemorrhage (3.56%/patient-year). There was no structural valve deterioration. Probability of freedom from all complications was $82.0{\pm}3.9%,\;71.3{\pm}4.8%\;and\;42.4{\pm}10.5%$ at 5, 10 and 20 years, respectively. Conclusion: We confirm the effective and excellent durability of the St. Jude Medical prosthesis in the mitral position with a low event rate at long-term follow-up. It also demonstrates the commonly encountered practical difficulty of adjusting the anti-coagulation protocol in patients with prosthetic mitral valves.

• Tuberculosis and Respiratory Diseases
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• v.46 no.3
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• pp.350-362
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• 1999

Background: Acute Respiratory failure which is developed after extubation in the weaning process from mechanical ventilation is an important cause of weaning failure. Once it was developed, endotracheal reintubation has been done for respiratory support. Noninvasive Positive Pressure Ventilation (NIPPV) has been used in the management of acute or chronic respiratory failure, as an alternative to endotracheal intubation, using via nasal or facial mask. In this study, we evaluated the usefulness of NIPPV as an alternative method of reintubation in patients who developed acute respiratory failure after extubation. Method: We retrospectively analyzed thirty one patients(eighteen males and thirteen females, mean ages $63\pm13.2$ years) who were developed acute respiratory failure within forty eight hours after extubation, or were extubated unintentionally at medical intensive care unit(MICU) of Asan Medical Center. NIPPV was applied to the patients. Ventilatory mode of NIPPV, level of ventilatory support and inspiratory oxygen concentration were adjusted according to the patient condition and results of blood gas analysis by the attending doctors at MICU. NIPPV was completely weaned when the patients maintained stable clinical condition under 8 $cmH_2O$ of pressure support level. Weaning success was defined as maintenance of stable spontaneous breathing more than forty eight hours after discontinuation of NIPPV. Respiratory rate, heart rate, arterial blood gas analysis, level of pressure support, and level of PEEP were monitored just before extubation, at thirty minutes, six hours, twenty four hours after initiation of NIPPV. They were also measured at just before weaning from NIPPV in success group, and just before reintubation in failure group. Results: NIPPV was successfully applied to thirty-one patients of thirty-two trials and one patient could not tolerated NIPPV longer than thirty minutes. Endotracheal reintubation was successfully obviated in fourteen patients (45%) among them. There was no difference in age, sex, APACHE III score on admission at MICU, duration of intubation, interval from extubation to initiation of NIPPV, baseline heart rate, respiratory rate, arterial blood gas, and $PaO_2/FiO_2$ between the success and the failure group. Heart rate and respiration rate were significantly decreased with increase $SaO_2$ after thirty minutes of NIPPV in both groups(p<0.05). However, in the patients of failure group, heart rate and respiratory rate were increased again with decrease in $SaO_2$ leading to endotracheal reintubation. The success rate of NIPPV treatment was significantly higher in the patients with COPD compared to other diseases(62% vs 39%) (p=0.007). The causes of failure were deterioration of arterial blood gas without aggravation of underlying disease(n=9), aggravation of undelying disease(n=5), mask intolerance(n=2), and retained airway secretion(n=l). Conclusion: NIPPV would be a useful therapeutic alternative which can avoid reintubation in patient who developed acute respiratory failure after extubation.