PURPOSE: The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIAL AND METHODS: Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest(R) ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS: Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION: Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.
Cyclic N-Oxides ; Zirconium

OBJECTIVES: This study was conducted to investigate the systematic error, such as seasonal change or inadequate food items, in a food frequency questionnaire administered to workers in a Nuclear Power Plant, Korea. METHODS: We performed three repeat-tests with 28 subjects on May 13, July 8 and Dec 16, 1992. Our food frequency questionnaire (FFQ) comprised 84 foods organized into 7 food-groups, and was composed of the items of usual intake frequency (8 categories) and the amount per intake (3 or 4 categories) over the previous year. We compared the means of intake frequency and the frequency of the portion-size according to each season using Repeated Measures ANOVA and Pearson's chisquare test with Fisher's exact test. RESULTS: We found the significant seasonal changes of several food items in intake frequency measurement. These items were typical seasonal foods such as mandarin orange, plum and green vegetables, while the single questions consisted of inadequate food items such as thick beef or similar soup and various kimchi products. Significant seasonal changes in portion-size were found in only two items: cooked rice-brown and fresh.frozen fishes. CONCLUSIONS: The systematic errors observed could caused loss of validity in the FFQ. Consideration should be given for seasonal variation in FFQ survey and methodological concerns are needed to improve the quality for measuring usual diet pattern.
*Diet Surveys ; Humans ; Korea ; *Power Plants ; Questionnaires ; Reproducibility of Results ; *Seasons

BACKGROUND: The use of dacron-cuffed tunneled double-lumen catheters for hemodialysis has become more common as patients wait for creation and maturation of a permanent access. Placement of the catheters is done by interventional radiologists, vascular surgeons or nephrologists, and the differences in success rates, complications, blood flow rates and the durations of catheter uses are reported. This study evaluated the usefulness, complications, blood flow rates and duration of use of tunneled cuffed hemodialysis catheters implanted via the internal jugular veins by an interventional radiologist and a vascular surgeon together. METHODS: The outcomes were retrospectively analyzed of 31 hemodialysis catheters placed from December 1999 through January 2001. We investigated age, sex, indications and locations of insertion, catheter performance, complications and causes of catheter removal. All the catheters were placed via the internal jugular veins by an interventional radiologist and a vascular surgeon together. RESULTS: Catheter placements were successful in all patients. Procedural complication was limited to clinically unimportant minor local bleeding. No instances of pneumothorax, hemothorax, vessel injury, substantial bleeding, obstruction, malposition or stenosis occurred. The blood flow rate on the first hemodialysis after placement of the catheter was 230+/-35.5 mL/min and that after 1 month was 248+/-18.6 mL/min. Late complications included catheter breakage in two cases (6.5%) and bacteremia in four cases (12.9%). Catheters were removed because of catheter-related bacteremia in four cases (12.9%) and death of patients in three cases (9.7%). In 22 cases (71.0%) the catheters were removed because the A- V vascular accesses were available for hemodialysis. Mean duration of the catheter use before removal was 134+/-96 days. CONCLUSION: Tunneled cuffed catheters inserted via the internal jugular veins are safe and durable vascular accesses for hemodialysis with good blood flow rate and long duration of use, especially placed by the co-operation of an interventional radiologist and a vascular surgeon.
Bacteremia ; Catheters* ; Constriction, Pathologic ; Hemorrhage ; Hemothorax ; Humans ; Jugular Veins* ; Pneumothorax ; Renal Dialysis* ; Retrospective Studies

Posttransplant erythrocytosis (PTE) is a common complication of renal transplantation, which can occur in approximately 10% to 15% of renal transplant patients and usually affects males with relatively good renal function. It is also associated with an increased incidence of thromboembolic events. Clinical manifestations of PTE include malaise, headache, plethora, lethargy, and dizziness. It is correlated with use of cyclosporin, gender, posttransplant renal function, and type of antihypertensive medication. The angiotensin receptor blocker (ARB) or angiotensin-converting enzyme inhibitor is preferred as an initial treatment for PTE because these agents are effective and reasonably safe in the majority of patients with PTE, and can also provide a necessary antihypertensive effect for kidney transplant patients. We report here on a 35-year-old male who had erythrocytosis after renal transplantation. After renal transplantation, his level of hemoglobin was 21 g/dL. We treated this patient with ARB and his symptoms and signs have been completely relieved.
Adult ; Angiotensin Receptor Antagonists ; Angiotensins ; Cyclosporine ; Dizziness ; Headache ; Humans ; Incidence ; Kidney Transplantation ; Kidney* ; Lethargy ; Male ; Polycythemia

STATEMENT OF PROBLEM: Titanium and its alloy, with their excellent bio-compatibility and above average resistance to corrosion, have been widely used in the field of dentistry. However, the excessive oxidization of titanium which occurs during the process of firing on porcelain makes the bonding of titanium and porcelain more difficult than that of the conventional metal-porcelain bonding. To solve this problem related to titanium-porcelain bonding, several methods which modify the surfaces, coat the surfaces of titanium with various pure metals and ceramics, to enable the porcelain adhesive by limiting the diffusion of oxygen and forming the adhesive oxides surfaces, have been investigated. PURPOSE: The purpose of this study was to know whether the titanium-porcelain bonding strength could be enhanced by treating the titanium surface with gold and TiN followed by fabrication of clinically applicable porcelain-fused-to-titanium crown. MATERIAL AND METHOD: The porcelain-fused-to-titanium crown was fabricated after sandblasting the surface of the casting titanium coping with Al2O3 and treating the surface with gold and TiN coating followed by condensation and firing of ultra-low fusing porcelain. To compare with porcelain-fused-to-titanium crowns, porcelain-fused-to-gold crowns were fabricated and used as control groups. The bonding strengths of porcelain-fused-to-gold crowns and porcelain-fused-totitanium crowns were set for comparison when the porcelain was fractured on purpose to get the experimental value of fracture strength. Then, the surface were examined by SEM and each fracturing pattern were compared with each other. RESULT: Those results are as follows. 1. The highest value of fracture strength of porcelain-fused-to-titanium crowns was in the order of group with gold coating, group with TiN coating, group with Al2O3 sandblasting. No statistically significant difference was found among the three (P>.05). 2. The porcelain-fused-to-gold crowns showed the highest value in bonding strength. The bonding strength of crowns porcelain-fused-to-titanium crowns of rest groups showed bonding strength reaching only 85%-94% of that of PFG, though simple comparision seemed unacceptable due to the difference in materials used. 3. The fracturing patterns between metal and porcelain showed mixed type of failure behavior including cohesive failure and adhesive failure as a similar patterns by examination with the naked eye and SEM. But porcelain-fused-to-gold crowns showed high incidence of adhesive failure and porcelain-fused-to-titanium crowns showed high incidence of cohesive failure. CONCLUSION: Above results proved that when fabricating porcelain-fused-to-titanium crowns, treating casting titanium surface with gold or TiN was able to enhance the bonding strength between titanium and porcelain. Mean value of masticatory force was found to showed clinically acceptable values in porcelain bonding strength in all three groups. However, more experimental studies and evaluations should be done in order to get better porcelain bonding strength and various surface coating methods that can be applied on titanium surface with ease.
Adhesives ; Alloys ; Bite Force ; Ceramics ; Corrosion ; Crowns* ; Dental Porcelain ; Dentistry ; Diffusion ; Fires ; Incidence ; Metals ; Oxides ; Oxygen ; Tin ; Titanium*

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, Al2O3 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 Al2O3 sandblasted wrought titanium(28.6at.% --> 8.3at.%). On the other hand, the least change was seen in Au-Pd-In alloy(24.5at.%--> 19.1at.%). 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 Au2Ti compound and TiN coating layers on Au and TiN coated surfaces and TiO2, 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.
Adhesives ; Corrosion ; Crowns ; Dental Porcelain* ; Diagnosis ; Diffusion ; Fires ; Hand ; Oxygen ; Tin ; Titanium* ; X-Ray Diffraction

BACKGROUND: The conventional cervicofacial flap may cause the aesthetic problem of sideburns with a mismatched shape and arrangement. We developed a modified method with the goals of minimizing the destruction of the shape and arrangement of the sideburns and minimizing complications in comparison with the conventional method. METHODS: The incision line was designed to descend just in front of the sideburns, without passing through them, and then to ascend with the sideburns posteriorly when a cervicofacial flap is performed, unlike the conventional method. Patients in whom this method was applied (group B) and patients who underwent surgery using the conventional method (group A) were investigated in a retrospective study. The method was evaluated by assessing changes in the arrangement of the sideburns and patients' satisfaction, and differences in the complication rate. RESULTS: In group A, 23 of the 31 patients experienced changes in the arrangement of their sideburns. Most patients who experienced a change in the arrangement of their sideburns were dissatisfied with the change. The patients in group B did not experience such changes, and the defects were well reconstructed. Most of them were satisfied with the final sideburn arrangement. CONCLUSION: A novel method was used to preserve the sideburns while performing a cervicofacial flap. As a result, the appearance of the sideburns was well preserved and the satisfaction of patients was also high. Moreover, this technique could also prove useful for reconstruction without any increase in complications compared to the conventional method.
Cheek ; Eyelids ; Humans ; Methods ; Retrospective Studies ; Surgical Flaps

PURPOSE: High voltage electrical injuries can cause many complications of central nervous system. We tried to define the indication range of brain CT (computerized tomography) in high voltage electrical injuries. METHODS: We performed a retrospective analysis of 51 high voltage electrical injured patients who were confirmed by brain CT, they had visited our emergency department from January 2005 to December 2007. All patients were classified by brain CT findings, presences of combined injuries and neurologic symptoms. RESULTS: 48 patients were confirmed normal in brain CT findings. 3 patients had brain lesions that were associated with secondary trauma. There was no abnormal CT finding in the 23 patients who did not have loss of consciousness, falling and combined injuries. CONCLUSION: If patient with electrical injury did not have neurologic symptoms or sufficient mechanical force, brain CT is not recommended. The results of this study may help emergency physicians to avoid unnecessary brain CT examination in the emergency triage to a high voltage electrical injury patients.
Brain ; Burns ; Central Nervous System ; Emergencies ; Humans ; Neurologic Manifestations ; Retrospective Studies ; Triage ; Unconsciousness

PURPOSE: The purpose of this study is to evaluate efficacy of percutaneous pinning of distal radioulnar joint in patient with distal radius fracture. METHODS: Thirty-eight patients who underwent percutaneous pinning and external fixation for distal radius fracture were included in this study. Radiologic and clinical outcomes were compared between the patients who underwent percutaneous pinning on the radius only (PD group) and the patients with supplementary pinning on distal radioulnar joint (DRU group) after percutaneous pinning on the radius. External fixation was performed in all patients. RESULTS: Twenty-three patients were PD group and fifteen patients were DRU group. Radial height and radial inclination was significantly higher in DRU group. There was no significant difference in ulnar variance, volar tilt and articular step off between two groups. Among the clinical outcome, there was no significant difference in range of motion between two groups but grip strength was significantly larger in DRU group. CONCLUSION: Percutaneous pinning with K-wires on distal radioulnar joint in distal radius fracture can be a useful procedure for prevention of radial shortening without loss of range of motion of the wrist.
Hand Strength ; Humans ; Joints* ; Radius ; Radius Fractures* ; Range of Motion, Articular ; Wrist

STATEMENT OF PROBLEM: The adhesion between titanium and ceramic is less optimal than conventional metal-ceramic bonding, due to reaction layer form on cast titanium surface during porcelain firing. PURPOSE: This study characterized the effect of titanium-ceramic adhesion after gold and TiN coating on cast and wrought titanium substrates. MATERIAL AND METHOD: Six groups of ASTM grade II commercially pure titanium and cast titanium specimens(13mm x 13mm x 1mm) were prepared(n=8). The conventional Au-Pd-In alloy served as the control. All specimens were sandblasted with 110micrometer Al2O3 particles and ultrasonically cleaned for 5min in deionized water, and dried in air before porcelain firing. An ultra-low-fusing dental porcelain(Vita Titankeramik) was fused on titanium surfaces. Porcelain was debonded by a biaxial flexure test at a cross head speed of 0.25mm/min. The excellent titanium-ceramic adherence was exhibited by the presence of a dentin porcelain layer on the specimen surface after the biaxial flexure test. Area fraction of adherent porcelain(AFAP) was determined by SEM/EDS. Numerical results were statistically analyzed by one-way ANOVA and Student- Newman-Keuls test at alpha=0.05. RESULTS: The AFAP value of cast titanium was greatest in the group 2 with TiN coating, followed by group 1 with Au coating and the group 3 with Al2O3 sandblasting. Significant statistical difference was found between the group 1, 2 and the group 3 (p<.05). The AFAP value of wrought titanium was greatest in the group 5 with TiN coating, followed by the group 4 with Au coating and the group 6 with Al2O3 sandblasting. CONCLUSION: No significant difference was observed among the three groups (p>.05). The AFAP values of the cast titanium and the wrought titanium were similar. However the group treated with Al2O3 sandblasting showed significantly lower value (p<.05).
Alloys ; Ceramics* ; Dental Porcelain ; Dentin ; Fires ; Head ; Tin ; Titanium* ; Water