1.Erratum: Predictive Value of Procalcitonin for Infection and Survival in Adult Cardiogenic Shock Patients Treated with Extracorporeal Membrane Oxygenation
Do Wan KIM ; Hwa Jin CHO ; Gwan Sic KIM ; Sang Yun SONG ; Kook Joo NA ; Sang Gi OH ; Bong Suk OH ; In Seok JEONG
Chonnam Medical Journal 2019;55(3):181-181
In the published article, the Figure 4 was published with incorrect y-axis and legend.
2.Predictive Value of Procalcitonin for Infection and Survival in Adult Cardiogenic Shock Patients Treated with Extracorporeal Membrane Oxygenation
Do Wan KIM ; Hwa Jin CHO ; Gwan Sic KIM ; Sang Yun SONG ; Kook Joo NA ; Sang Gi OH ; Bong Suk OH ; In Seok JEONG
Chonnam Medical Journal 2018;54(1):48-54
Procalcitonin (PCT) is a predictive marker for the occurrence of bacterial infection and the decision to terminate antibiotic treatment in critically ill patients. An unusual increase in PCT, regardless of infection, has been observed during extracorporeal membrane oxygenation (ECMO) support. We evaluated trends and the predictive value of PCT levels in adult cardiogenic shock during treatment with ECMO. We reviewed the clinical records of 38 adult cardiogenic shock patients undergoing veno-arterial ECMO support between January 2014 and December 2016. The exclusion criteria were age < 18 years, pre-ECMO infection, and less than 48 hours of support. The mean patient age was 56.7±14.7 years and 12 (31.6%) patients were female. The mean duration of ECMO support was 9.0±7.6 days. The rates of successful ECMO weaning and survival to discharge were 55.3% (n=21) and 52.6% (n=20), respectively. There were 17 nosocomial infections in 16 (42.1%) patients. Peak PCT levels (mean 25.6±9.4 ng/mL) were reached within 48 hours after initiation of ECMO support and decreased to ≤5 ng/mL within one week. The change in PCT levels was not useful in predicting the occurrence of new nosocomial infections during the ECMO run. However, a PCT level >10 ng/mL during the first week of ECMO support was significantly associated with mortality (p < 0.01). The change in PCT level was not useful in predicting new infection during ECMO support. However, higher PCT levels within the first week of the ECMO run are associated with significantly higher mortality.
Adult
;
Bacterial Infections
;
Calcitonin
;
Critical Illness
;
Cross Infection
;
Extracorporeal Membrane Oxygenation
;
Female
;
Humans
;
Mortality
;
Shock
;
Shock, Cardiogenic
;
Weaning
3.Nosocomial Infection in Adult Patients Undergoing Veno-Arterial Extracorporeal Membrane Oxygenation.
Gwan Sic KIM ; Kyo Seon LEE ; Choung Kyu PARK ; Seung Ku KANG ; Do Wan KIM ; Sang Gi OH ; Bong Suk OH ; Yochun JUNG ; Seok KIM ; Ju Sik YUN ; Sang Yun SONG ; Kook Joo NA ; In Seok JEONG ; Byoung Hee AHN
Journal of Korean Medical Science 2017;32(4):593-598
Data on the frequency of nosocomial infections during extracorporeal membrane oxygenation (ECMO) in adult populations remain scarce. We investigated the risk factors for nosocomial infections in adult patients undergoing venoarterial ECMO (VA-ECMO) support. From January 2011 to December 2015, a total of 259 patients underwent ECMO. Of these, patients aged 17 years or less and patients undergoing ECMO for less than 48 hours were excluded. Of these, 61 patients diagnosed with cardiogenic shock were evaluated. Mean patient age was 60.6 ± 14.3 years and 21 (34.4%) patients were female. The mean preoperative Sequential Organ Failure Assessment (SOFA) score was 8.6 ± 2.2. The mean duration of ECMO support was 6.8 ± 7.4 days. The rates of successful ECMO weaning and survival to discharge were 44.3% and 31.1%, respectively. There were 18 nosocomial infections in 14 (23.0%) patients. These included respiratory tract infections in 9 cases and bloodstream infections in a further 9. In multivariate analysis, independent predictors of infection during ECMO were the preoperative creatinine level (hazard ratio [HR], 2.176; 95% confidence interval [CI], 1.065–4.447; P = 0.033) and the duration of ECMO support (HR, 1.400; 95% CI, 1.081–1.815; P = 0.011). A higher preoperative creatinine level and an extended duration of ECMO support are risk factors for infection. Therefore, to avoid the development of nosocomial infections, strategies to shorten the length of ECMO support should be applied whenever possible.
4.Comparison of Coronary Plaque and Stenosis Between Coronary Computed Tomography Angiography and Virtual Histology-Intravascular Ultrasound in Asymptomatic Patients with Risk Factors for Coronary Artery Disease.
Young Joon HONG ; Myung Ho JEONG ; Yun Ha CHOI ; Soo Young PARK ; Hyun Ju SEON ; Hyun Sung LEE ; Yun Hyun KIM ; Sang Cheol CHO ; Jae Young CHO ; Hae Chang JEONG ; Soo Young JANG ; Jong Hyun YOO ; Ji Eun SONG ; Ki Hong LEE ; Keun Ho PARK ; Doo Sun SIM ; Nam Sik YOON ; Hyun Ju YOON ; Kye Hun KIM ; Hyung Wook PARK ; Ju Han KIM ; Youngkeun AHN ; Jeong Gwan CHO ; Jong Chun PARK ; Jung Chaee KANG
Journal of Lipid and Atherosclerosis 2014;3(2):79-87
OBJECTIVES: The purpose of the study was to compare plaque characteristics by coronary computed tomography angiography (CCTA) with those by virtual histology-intravascular ultrasound (VH-IVUS). METHODS: We enrolled 50 asymptomatic patients with diabetes mellitus or more than two risk factors for coronary artery disease such as hypertension, smoking, and hyperlipidemia. If the patient had a coronary lesion (plaque with more than 50% stenosis or calcium score more than 100), we recommended coronary angiography and VH-IVUS and compared CCTA findings with VH-IVUS findings. RESULTS: 35 patients (70%) had coronary lesions, and we performed both CCTA and VH-IVUS in 23 patients. All 23 patients had multiple risk factors, and the majority of target lesions were located at left anterior descending artery (73.9%), and calcium score of lesion site was 106+/-162 with plaque volume of 232+/-153 mm3 by CCTA. Calcium score of lesion site was significantly greater in diabetic patients (n=14) than non-diabetic patients (n=9) (118+/-159 vs. 88+/-175, p=0.038). By VH-IVUS, plaque volume was 174+/-127 mm3, absolute necrotic core (NC) volume was 22+/-21 mm3, and relative NC volume was 20.8+/-8.7%. Absolute dense calcium (DC) volume and absolute NC volumes were significantly greater in diabetic patients than non-diabetic patients (11.5+/-13.8 mm3 vs. 9.1+/-11.0 mm3, p=0.028, and 23.9+/-24.7 mm3 vs. 18.1+/-14.3 mm3, p=0.035, respectively). Plaque volume by CCTA correlated with that of VH-IVUS (r=0.742, p<0.001), and plaque volume by CCTA correlated with absolute NC volume by VH-IVUS (r=0.621, p<0.001), and calcium score of lesion site by CCTA correlated with absolute dense calcium volume by VH-IVUS (r=0.478, p=0.028). CONCLUSION: Coronary lesion was detected by CCTA in 70% of asymptomatic patients with multiple coronary risk factors, and parameters detected by CCTA correlated well with those detected by VH-IVUS.
Angiography*
;
Arteries
;
Calcium
;
Constriction, Pathologic*
;
Coronary Angiography
;
Coronary Artery Disease*
;
Diabetes Mellitus
;
Humans
;
Hyperlipidemias
;
Hypertension
;
Risk Factors*
;
Smoke
;
Smoking
;
Ultrasonography*
5.The Clinical Significance of Specialized Intestinal Metaplasia in the Diagnosis of Barrett's Esophagus: Nationwide Prospective Multicenter Study.
Hyun Kyung PARK ; Nayoung KIM ; Byoung Hwan LEE ; Jin Il KIM ; So Young LEE ; Hyun Min CHA ; Hyerang KIM ; Soo Hyun PARK ; Jong Jae PARK ; Sang Woo LEE ; Ki Nam SHIM ; Seong Eun KIM ; Su Jin HONG ; Il Kwun CHUNG ; Gwang Ho BAIK ; Hyun Soo KIM ; Sungkook KIM ; Jae Kyu SEONG ; Geom Seog SEO ; Sam Ryong JEE ; Jeong Seop MOON ; Mee Yon CHO ; Jae Woo KIM ; Moon Gi CHUNG ; Seon Mee PARK ; Byung Kyu NAH ; Su Youn NAM ; Kang Seok SEO ; Byung Sung KO ; Yun Ju JO ; Jae Young JANG ; Byeong Gwan KIM ; Ji Won KIM ; Kyung Sik PARK ; Hyun Shin PARK ; Young Sun KIM ; Seon Hee LIM ; Chung Hyeon KIM ; Min Jung PARK ; Jeong Yoon YIM ; Kyung Ran CHO ; Donghee KIM ; Seun Ja PARK ; Geun Am SONG ; Hyun Jin KIM ; Sang Wook KIM ; Eui Hyeog IM ; Kyoung Soo LEE ; Dong Hyo HYUN ; Hyun Young KIM ; Sun Mi KIM ; Jeong Eun SHIN ; Chan Guk PARK ; Chang Hun YANG ; Soo Heon PARK ; Hyun Chae JUNG ; In Sik CHUNG
The Korean Journal of Helicobacter and Upper Gastrointestinal Research 2012;12(3):171-177
BACKGROUND/AIMS: The meaning of specialized intestinal metaplasia (SIM) in the diagnosis of Barrett's esophagus (BE) is not clear. This study was designed to determine the clinical significance of SIM in the diagnosis of Barrett's esophagus. MATERIALS AND METHODS: Biopsies were taken from 601 subjects with endoscopically suspected columnar-lined esophagus. Under light microscopy with Alcian-blue stain, SIM was identified. Demographic characteristics, gastroesophageal (GE) reflux symptoms and endoscopic findings were compared between the SIM-present group and the SIM-absent group. RESULTS: Among 601 subjects, 184 (30.6%) were confirmed by pathology to have SIM. Age over 40 years (P<0.001) and a medication history of proton pump inhibitor or H2 blocker were found more frequently in the SIM-present group (P=0.01) than in the SIM-absent group. Any of 7 GE reflux symptoms (heartburn, acid regurgitation, chest pain, hoarseness, globus sensation, cough and epigastric soreness) were more frequent in the SIM-present group than SIM-absent group (P<0.001). Specifically, heartburn, chest pain and cough were significantly more common in the SIM-present group. There was no clinically significant difference associated with endoscopic findings or other clinical characteristics. CONCLUSIONS: When subjects with endoscopically suspected BE are analyzed based on the presence or absence of SIM, the SIM-present group was significantly associated with GE reflux symptoms suggestive of frequent GE reflux. However, the presence of SIM did not correlate with endoscopic findings.
Barrett Esophagus
;
Biopsy
;
Chest Pain
;
Cough
;
Esophagus
;
Gastroesophageal Reflux
;
Heartburn
;
Hoarseness
;
Light
;
Metaplasia
;
Microscopy
;
Prospective Studies
;
Proton Pumps
;
Sensation
6.Relation between Anemia and Vulnerable Coronary Plaque Components in Patients with Acute Coronary Syndrome: Virtual Histology-Intravascular Ultrasound Analysis.
Young Joon HONG ; Myung Ho JEONG ; Yun Ha CHOI ; Jin A SONG ; Dong Han KIM ; Ki Hong LEE ; Futoshi YAMANAKA ; Min Goo LEE ; Keun Ho PARK ; Doo Sun SIM ; Nam Sik YOON ; Hyun Ju YOON ; Kye Hun KIM ; Hyung Wook PARK ; Ju Han KIM ; Youngkeun AHN ; Jeong Gwan CHO ; Jong Chun PARK ; Jung Chaee KANG
Journal of Korean Medical Science 2012;27(4):370-376
The aim of the present study was to evaluate the plaque components and the predictors of thin-cap fibroatheroma (TCFA) in anemic patients with acute coronary syndrome using virtual histology-intravascular ultrasound (VH-IVUS). Anemia was defined according to criteria of the World Health Organization, (i.e. , hemoglobin levels < 13 g/dL in men and < 12 g/dL in women) and we compared VH-IVUS findings between anemia group (171 patients, 260 lesions) and non-anemia group (569 patients, 881 lesions). Anemia group had greater % necrotic core (NC) volume (21% +/- 9% vs 19% +/- 9%, P = 0.001) compared with non-anemia group. Hemoglobin level correlated negatively with absolute NC volume (r = -0.235, P < 0.001) and %NC volume (r = -0.209, P < 0.001). Independent predictors of TCFA by multivariate analysis were diabetes mellitus (odds ratio [OR], 2.213; 95% confidence interval [CI], 1.403-3.612, P = 0.006), high-sensitivity C-reactive protein (OR, 1.143; 95% CI, 1.058-1.304, P = 0.012), microalbuminuria (albumin levels of 30 to 300 mg/g of creatinine) (OR, 2.124; 95% CI, 1.041-3.214, P = 0.018), and anemia (OR: 2.112; 95% CI 1.022-3.208, P = 0.028). VH-IVUS analysis demonstrates that anemia at the time of clinical presentation is associated with vulnerable plaque component in patients with acute coronary syndrome.
Acute Coronary Syndrome/complications/*pathology/ultrasonography
;
Aged
;
Albuminuria/urine
;
Anemia/complications/*diagnosis
;
C-Reactive Protein/analysis
;
Coronary Angiography
;
Creatinine/blood
;
Diabetes Complications
;
Female
;
Hemoglobins/analysis
;
Humans
;
Male
;
Middle Aged
;
Necrosis/pathology
;
Odds Ratio
;
Plaque, Atherosclerotic/*ultrasonography
;
Predictive Value of Tests
;
*Ultrasonography, Interventional
7.The Distribution of Endoscopic Gastritis in 25,536 Heath Check-up Subjects in Korea.
Hyun Kyung PARK ; Nayoung KIM ; Sang Woo LEE ; Jong Jae PARK ; Jin Il KIM ; So Young LEE ; Hyun Min CHA ; Hyerang KIM ; Soo Hyun PARK ; Ki Nam SHIM ; Seong Eun KIM ; Su Jin HONG ; Il Kwun CHUNG ; Gwang Ho BAIK ; Hyun Soo KIM ; Sungkook KIM ; Jae Kyu SEONG ; Geom Seog SEO ; Sam Ryong JEE ; Jeong Seop MOON ; Jae Woo KIM ; Moon Gi CHUNG ; Seon Mee PARK ; Byung Kyu NAH ; Su Youn NAM ; Kang Seok SEO ; Byung Sung KO ; Yun Ju JO ; Jae Young JANG ; Byeong Gwan KIM ; Ji Won KIM ; Kyung Sik PARK ; Hyun Shin PARK ; Young Sun KIM ; Seon Hee LIM ; Chung Hyeon KIM ; Min Jung PARK ; Jeong Yoon YIM ; Kyung Ran CHO ; Donghee KIM ; Seun Ja PARK ; Geun Am SONG ; Hyun Jin KIM ; Sang Wook KIM ; Eui Hyeog IM ; Kyoung Soo LEE ; Dong Hyo HYUN ; Hyun Young KIM ; Sun Mi KIM ; Jeong Eun SHIN ; Chan Guk PARK ; Chang Hun YANG ; Soo Heon PARK ; Hyun Chae JUNG ; In Sik CHUNG
The Korean Journal of Helicobacter and Upper Gastrointestinal Research 2012;12(4):237-243
BACKGROUND/AIMS: Chronic gastritis is a common finding during endoscopy and it is very important to describe it correctly. This study was designed to evaluate the distribution of endoscopic gastritis and the differences according to age, sex or area. MATERIALS AND METHODS: A clinical analysis was conducted on 25,536 subjects who had undergone an upper endoscopy for routine health check-up. Endoscopic gastritis was classified into four types, superficial gastritis, erosive gastritis, atrophic gastritis and intestinal metaplasia. The distribution of the four types of gastritis was evaluated according to sex, age and area. RESULTS: 51.6% of the patients had experienced at least one of the symptoms (epigastric pain or discomfort, soarness, dyspepsia, abdominal pain) on at least a few occasions during the previous year. The incidence of normal gastric finding was 3,593 (14.1%). 21,943 (85.9%) subjects have at least more than one of endoscopic gastritis. The number of cases with superficial gastritis was 7,983 (31.3%), erosive gastritis 6,054 (23.7%), atrophic gastritis 6,918 (27.1%), and intestinal metaplasia 1,181 (7.1%). Erosive gastritis, atrophic gastritis and intestinal metaplasia were more frequent in men than women (P<0.001) and in the older age group (> or =60 years) than younger age group (P<0.001). CONCLUSIONS: The prevalence of endoscopic gastritis was very common, 85.9%. In addition, erosive gastritis, atrophic gastritis and intestinal metaplasia were more frequent in men and in the older age group, which is similar to gastric cancer or peptic ulcer. Cautious regular endoscopic follow-up might be necessary regardless of gastrointestinal symptoms in Korea.
Dyspepsia
;
Endoscopy
;
Female
;
Gastritis
;
Gastritis, Atrophic
;
Helicobacter pylori
;
Humans
;
Incidence
;
Korea
;
Male
;
Metaplasia
;
Peptic Ulcer
;
Prevalence
;
Stomach Neoplasms
8.The Distribution of Endoscopic Gastritis in 25,536 Heath Check-up Subjects in Korea.
Hyun Kyung PARK ; Nayoung KIM ; Sang Woo LEE ; Jong Jae PARK ; Jin Il KIM ; So Young LEE ; Hyun Min CHA ; Hyerang KIM ; Soo Hyun PARK ; Ki Nam SHIM ; Seong Eun KIM ; Su Jin HONG ; Il Kwun CHUNG ; Gwang Ho BAIK ; Hyun Soo KIM ; Sungkook KIM ; Jae Kyu SEONG ; Geom Seog SEO ; Sam Ryong JEE ; Jeong Seop MOON ; Jae Woo KIM ; Moon Gi CHUNG ; Seon Mee PARK ; Byung Kyu NAH ; Su Youn NAM ; Kang Seok SEO ; Byung Sung KO ; Yun Ju JO ; Jae Young JANG ; Byeong Gwan KIM ; Ji Won KIM ; Kyung Sik PARK ; Hyun Shin PARK ; Young Sun KIM ; Seon Hee LIM ; Chung Hyeon KIM ; Min Jung PARK ; Jeong Yoon YIM ; Kyung Ran CHO ; Donghee KIM ; Seun Ja PARK ; Geun Am SONG ; Hyun Jin KIM ; Sang Wook KIM ; Eui Hyeog IM ; Kyoung Soo LEE ; Dong Hyo HYUN ; Hyun Young KIM ; Sun Mi KIM ; Jeong Eun SHIN ; Chan Guk PARK ; Chang Hun YANG ; Soo Heon PARK ; Hyun Chae JUNG ; In Sik CHUNG
The Korean Journal of Helicobacter and Upper Gastrointestinal Research 2012;12(4):237-243
BACKGROUND/AIMS: Chronic gastritis is a common finding during endoscopy and it is very important to describe it correctly. This study was designed to evaluate the distribution of endoscopic gastritis and the differences according to age, sex or area. MATERIALS AND METHODS: A clinical analysis was conducted on 25,536 subjects who had undergone an upper endoscopy for routine health check-up. Endoscopic gastritis was classified into four types, superficial gastritis, erosive gastritis, atrophic gastritis and intestinal metaplasia. The distribution of the four types of gastritis was evaluated according to sex, age and area. RESULTS: 51.6% of the patients had experienced at least one of the symptoms (epigastric pain or discomfort, soarness, dyspepsia, abdominal pain) on at least a few occasions during the previous year. The incidence of normal gastric finding was 3,593 (14.1%). 21,943 (85.9%) subjects have at least more than one of endoscopic gastritis. The number of cases with superficial gastritis was 7,983 (31.3%), erosive gastritis 6,054 (23.7%), atrophic gastritis 6,918 (27.1%), and intestinal metaplasia 1,181 (7.1%). Erosive gastritis, atrophic gastritis and intestinal metaplasia were more frequent in men than women (P<0.001) and in the older age group (> or =60 years) than younger age group (P<0.001). CONCLUSIONS: The prevalence of endoscopic gastritis was very common, 85.9%. In addition, erosive gastritis, atrophic gastritis and intestinal metaplasia were more frequent in men and in the older age group, which is similar to gastric cancer or peptic ulcer. Cautious regular endoscopic follow-up might be necessary regardless of gastrointestinal symptoms in Korea.
Dyspepsia
;
Endoscopy
;
Female
;
Gastritis
;
Gastritis, Atrophic
;
Helicobacter pylori
;
Humans
;
Incidence
;
Korea
;
Male
;
Metaplasia
;
Peptic Ulcer
;
Prevalence
;
Stomach Neoplasms
9.Occupational disease surveillance system in Busan, Ulsan, Kyung-Nam area.
Jung Il KIM ; Byung Gwan KIM ; Jung Won KIM ; Chang Ho CHAE ; Cheol Ho YI ; Dongmug KANG ; Ji Hong KIM ; Jin Ha KIM ; Young Wook KIM ; Young Ha LEE ; Ji Ho LEE ; Younghee CHOI ; Jung Ho KIM ; Hyung Ryul YUN ; Cheol In YOO ; Baek Geun JEONG ; Tae Won JANG ; Yun Gyu KIM ; Dong Young YUN ; Jin Uk KANG ; Jong Eun KIM ; Jin Hong AHN ; Dong Joon LEE ; Joon Ho JANG ; Kwang Young LEE ; Hyu Ran SONG ; Yong Hwan LEE ; Byung Man CHO ; Hong Ryul CHOI ; Sang Baek KOH ; Euna KIM ; Yu Jin LEE ; Young Seoub HONG ; Kap Yeol JUNG ; Jung Man KIM ; Joon Youn KIM
Korean Journal of Occupational and Environmental Medicine 2004;16(1):1-12
OBJECTIVE: Occupational medicine specialists in the Busan, Ulsan and Kyung-Nam areas established an area-based occupational disease surveillance system and used this system to collected case information for the purpose of preventing occupational diseases METHODS: 11 hospitals participated in this system. The authors selected five main diseases, which were hand-arm vibration syndrome (HAVS), work-related musculoskeletal disorder (WRMSD), occupational asthma, occupational skin disease and occupational lung cancer and established their case definitions. All cases were reported on the web, and real time analysis was conducted. RESULTS: Between Apri1 2001 and April 2003, 192 cases of HAVS, 118 cases of WRMSD, 33 cases of occupational asthma, 17 cases of occupational skin disease and 17 cases of occupational lung cancer (for a total of 377 cases of these five main diseases) were reported. Most of the HAVS cases came from shipbuilding, and 172 of them (92.7 %) were associated with grinding. Of the four main types of WRMSD, carpal tunnel syndrome (CTS) was the most prevalent with 46 cases and shipbuilding was also the main industry involved (83.9 %). The ergonomic risk factors involved mainly associated with the hand. In 19 (57.6 %) and 4 (12.1 %) cases of occupational asthma, the agents included isocyanate and welding fume, respectively. 64.7 % of the cases of occupational skin diseases were contact dermatitis, and organic solvents and welding fume were the main agents involved. The causative agents of occupational lung cancer included Cr, welding fume, PAH, Ni, etc. 10 (58.8 %) of the cases were diagnosed as squamous cell carcinoma and 5 (29.4 %) as adenoma. CONCLUSION: This result showed that an area-based occupational disease surveillance system might provide an effective method of evaluating the prevalence of such diseases, however the Busan, Ulsan and Kyung-Nam provinces are too large to be treated as individual areas. Therefore, the authors suggest that each province should establish its own surveillance system.
Adenoma
;
Asthma, Occupational
;
Busan*
;
Carcinoma, Squamous Cell
;
Carpal Tunnel Syndrome
;
Dermatitis, Contact
;
Hand
;
Hand-Arm Vibration Syndrome
;
Lung Neoplasms
;
Occupational Diseases*
;
Occupational Medicine
;
Prevalence
;
Risk Factors
;
Skin Diseases
;
Solvents
;
Specialization
;
Ulsan*
;
Welding
10.TENSILE STRENGTH OF LASER WELDED-TITANIUM AND GOLD ALLOYS.
Yun Gwan SONG ; Kwang Yeob SONG ; Il Soo HA
The Journal of Korean Academy of Prosthodontics 2000;38(2):200-213
Lasers have given dentistry a new rapid, economic, and accurate technique for metal joining. Although laser welding has been recommended as an accurate technique, there are some limitations with this technique. For example, the two joining surfaces must have a tight-fitting contact, which may be difficult to achieve in some situations. The tensile samples used for this study were made from a custom-made pure titanium and type III gold alloy plates. 27 of 33 specimens were sectioned perpendicular to their long axis with a carborundum disk and water coolant. Six specimens remained and served as the control group. A group of 6 specimens was posed as butt joints in custom parallel positioning device with a feeler gauge at each of three gaps : 0.00, 0.25, and 0.50mm. All specimens were then machined to produce a uniform cross-sectional dimension, none of the specimens was subjected to any subsequent form of heat treatment. Scanning electron microscopy was performed on representative tested specimens at fractured surfaces in both the parent metal and the weld. Vickers hardness was measured at the center of the welds with a micropenetrometer using a force of 300gm for 15 seconds. Measurement was made at approximately 200 ,am and 500 pm deep from each surface. One-way analysis of variance (ANOVA) and Scheffe' s test was calculated to detect differences between groups. The purpose of this study is to compare the strength and properties of the joint achieved at various butt joint gaps by the laser welding of type III gold alloy and pure titanium tensile specimens in an argon atmosphere. The results of this study were as follows 1. When indexing and welding pure titanium, there was no decrease in ultimate tensile strength as compared with the unsectioned alloys for indexing gaps of 0.00 to 0.50mm, although with increasing gap size may come increased distortion (p>0.05). 2. When indexing and welding type III gold alloy, there were significant differences in ultimate tensile strength among groups with weld gaps of 0.00mm, 0.25 and 0.50mm, and the control group. Group with butt contact without weld gap demonstrated a significant higher ultimate tensile strength than groups with weld gaps of 0.25 and 0.50mm (p<0.05) . 3. When indexing and welding the different metal combination of type III gold alloy and pure titanium, there were significant differences in ultimate tensile strength between groups with weld gaps of 0.00, 0.25, and 0.50mm. However, the mechanical properties of the welded joint would become too brittle to be acceptable clinically (p<0.05) . 4. The presence of large pores in the laser welded joint appears to be the most important factor in controlling the tensile strength of the weld in both pure titanium and type III gold alloy.
Abstracting and Indexing as Topic
;
Alloys
;
Argon
;
Atmosphere
;
Axis, Cervical Vertebra
;
Dentistry
;
Gold Alloys*
;
Hardness
;
Hot Temperature
;
Humans
;
Joints
;
Microscopy, Electron, Scanning
;
Parents
;
Tensile Strength*
;
Titanium
;
Water
;
Welding

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