Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
Hepatol Res ; 50(11): 1244-1254, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32822521

RESUMEN

Portopulmonary hypertension (PoPH) is a well-known complication of liver cirrhosis. The aim of this study was to clarify the pulmonary hemodynamics and the prevalence and characteristics of PoPH in patients with portal hypertension. METHODS: The subjects were 335 patients with portal hypertension diagnosed by hepatic vein pressure gradient (HVPG). Among them, 186 patients received measurements of pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP) and pulmonary vascular resistance (PVR). PoPH was diagnosed by PAP >20 mmHg, PVR ≥3 Wood units (WU) and PAWP ≤15 mmHg. RESULTS: The Child-Pugh classification was class A in 53, B in 92 and C in 41 patients. Median (range) values of HVPG, PAP, PVR and PAWP were 18.4 (5.5-39.0) mmHg, 12.9 (6.6-40.8) mmHg, 0.8 (0.1-4.5) WU and 7.5 (2.2-15.4) mmHg, respectively. Of six patients with PAP >20 mmHg, four had autoimmune hepatitis or primary biliary cholangitis, with the prevalence being significantly higher than that in patients with PAP ≤20 mmHg. Meanwhile, no significant difference was noted in the hepatic functional reserve or HVPG between patients with PAP >20 mmHg and ≤20 mmHg. Only two patients met the diagnostic criteria of PoPH and both patients were Child-Pugh B. The Child-Pugh score and HVPG were not associated with PoPH. CONCLUSIONS: Our study demonstrated that only two patients were complicated by PoPH. High PAP values were noted in patients with primary biliary cholangitis or autoimmune hepatitis. However, the presence of PoPH and high PAP were not associated with the degree of hepatic functional reserve or HVPG.

2.
Int J Syst Evol Microbiol ; 67(6): 1841-1848, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28629495

RESUMEN

Thirty-nine denitrifying bacterial strains closely related to one another, represented by strains TSA40T and TSA66T, were isolated from rice paddy soils. Strains TSA40T and TSA66T were Gram-stain-negative, slightly curved rod-shaped, and motile by means of polar flagella. They were able to reduce nitrate, nitrite and nitrous oxide, but unable to fix atmospheric N2. While strain TSA66T was able to grow autotrophically by H2-dependent denitrification, strain TSA40T could not. Phylogenetic analysis suggested that they belong to the family Oxalobacteraceae, the order Burkholderiales in the class Betaproteobacteria. Major components in the fatty acids (C16 : 0, C17 : 0 cyclo, C18 : 1ω7c and summed feature 3) and quinone (Q-8) also supported the affiliation of strains TSA40T and TSA66T to the family Oxalobacteraceae. Based on 16S rRNA gene sequence comparisons, strains TSA40T and TSA66T showed the greatest degree of similarity to Herbaspirillum massiliense JC206T, Noviherbaspirillum malthae CC-AFH3T, Noviherbaspirillum humi U15T, Herbaspirillum seropedicae Z67T and Paucimonas lemoignei LMG 2207T, and lower similarities to the members of other genera. Average nucleotide identity values between the genomes of strain TSA40T, TSA66T and H. massiliense JC206T were 75-77 %, which was lower than the threshold value for species discrimination (95-96 %). Based on the 16S rRNA gene sequence analysis in combination with physiological, chemotaxonomic and genomic properties, strains TSA40T (=JCM 17722T=ATCC TSD-69T) and TSA66T (=JCM 17723T=DSM 25787T) are the type strains of two novel species within the genus Noviherbaspirillum, for which the names Noviherbaspirillum denitrificans sp. nov. and Noviherbaspirillum autotrophicum sp. nov. are proposed, respectively. We also propose the reclassification of Herbaspirillum massiliense as Noviherbaspirillum massiliense comb. nov.


Asunto(s)
Herbaspirillum/clasificación , Oryza , Filogenia , Microbiología del Suelo , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Desnitrificación , Ácidos Grasos/química , Herbaspirillum/genética , Herbaspirillum/aislamiento & purificación , ARN Ribosómico 16S/genética , República de Corea , Análisis de Secuencia de ADN
3.
Surg Case Rep ; 10(1): 228, 2024 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-39365380

RESUMEN

BACKGROUND: Histiocytic sarcoma (HS) is a rare disease characterized by the presence of neoplastic histiocytes. We herein report an unusual case of HS that caused massive tumor embolism-related transmural necrosis of the small intestine. CASE PRESENTATION: A 64-year-old man presented with multiple nodules in the lungs, bone, mediastinum, and subcutaneous tissues that were incidentally detected on preoperative computed tomography for early transverse colon cancer. Approximately two months later, the patient presented with signs of peritoneal irritation suggestive of small intestinal necrosis. Emergency surgery was performed and the necrotic small intestine was resected. Pathological examination revealed small bowel necrosis due to multifocal HS embolism. The postoperative course was uneventful. The patient was unsuccessfully treated with chemotherapy for HS and died 122 days postoperatively. CONCLUSIONS: HS can cause massive enteric necrosis due to tumor embolism. Clinicians should be aware of this rare presentation of HS.

4.
Oncol Lett ; 28(2): 365, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38933808

RESUMEN

Adjuvant chemotherapy is usually not considered for pT1a pN0 human epidermal growth factor receptor 2 (HER2)-positive breast cancer due to its low recurrence rate. The present report describes a case of pT1a hormone receptor-positive HER2-positive breast cancer with multiple recurrences in the axillary lymph nodes and liver within 1 year after radical surgery. A 58-year-old woman underwent left total mastectomy and sentinel lymph node biopsy for left breast cancer with pathological stage IA (pT1a pN0). The subtype corresponded to luminal B-like breast cancer with a nuclear grade of 3 and a Ki-67 labeling index of 37%. An aromatase inhibitor (letrozole) was planned to be administered for 5 years after surgery, but the patient was diagnosed with multiple liver and axillary lymph node metastases 11 months after surgery. After 1 year of chemotherapy (paclitaxel) in combination with anti-HER2 therapy (pertuzumab and trastuzumab), liver metastases resolved. A complete response of the liver lesion has been maintained 4 years after the anti-HER2 therapy initiation. The present case exhibited two poor prognostic factors: High Ki-67 labeling index and nuclear grade 3. Based on the 'Predict' tool, the present case would be expected to have a cancer-related mortality rate of 6% 10 years after surgery with adjuvant endocrine therapy. Although this value may be controversial for postoperative anti-HER2 therapy, the present case should not be considered to be a low-risk case. When the identification of high-risk pT1a pN0 HER2-positive breast cancer is possible, postoperative anti-HER2 therapy plus chemotherapy would be effective in decreasing the rate of recurrence.

5.
BJR Case Rep ; 10(1): uaad009, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38352257

RESUMEN

A 44-year-old man presented with a chief complaint of constipation. Initial contrast-enhanced CT showed extensive bowel wall thickening, mainly in the left colon, with a thin cord-like inferior mesenteric vein (IMV), in contrast to ectatic mesenteric venous branches, suggesting bowel ischaemia owing to venous stasis. One month later, at the time of symptom exacerbation, CT angiography showed a cord-like IMV and ectatic mesenteric venous branches with early enhancement, suggesting the presence of an arteriovenous fistula (AVF). Owing to the progression of bowel ischaemia and necrosis with peritonitis, emergency surgery was performed. Surgical specimens showed focal myointimal hyperplasia of the proximal mesenteric veins in both ischaemic and non-ischaemic lesions of the resected colon, thus leading to the diagnosis of idiopathic myointimal hyperplasia of mesenteric veins (IMHMV) when combined with the clinical and imaging findings. IMHMV is a bowel ischaemic disease caused by non-thrombotic venous obstruction that requires bowel resection and has been suggested to be associated with AVF. Cord-like IMV and AVF in the mesentery are important CT findings that characterize IMHMV. CT angiography is useful in diagnosing IMHMV.

6.
Eur J Orthod ; 33(3): 293-7, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20805141

RESUMEN

The aims of this study were to investigate the torsional properties of three experimental titanium miniscrew implants for orthodontic anchorage and to determine the relationship between the torsional properties and metallurgical structures. Experimental miniscrew implants with a diameter of 1.4 mm were fabricated from commercially pure (CP) titanium (alpha-titanium), Ti-4Al-4V (duplex alpha-beta-titanium), and Ti-33Nb-15Ta-6Zr (beta-titanium). Micro-X-ray diffraction (XRD) was performed to identify phases, and microstructures of etched cross-sections were obtained with scanning electron microscopy (SEM). Implants were loaded in torsion (n = 5), and mean moments and twist angles at fracture were statistically compared using the Kruskal-Wallis and Mann-Whitney U-tests. Cyclic torsional moment for fracture of starting square wires (2 × 2 × 30 mm) was measured (n = 3). At fracture, the Ti-4Al-4V and Ti-33Nb-15Ta-6Zr implants demonstrated significantly higher mean torque than the CP titanium implant, while the Ti-33Nb-15Ta-6Zr implant had a significantly higher mean twist angle than the other two implants. The CP titanium and Ti-33Nb-15Ta-6Zr implants displayed good fatigue performance and excellent ductility. Ti-33Nb-15Ta-6Zr beta-titanium alloy is suitable for manufacturing miniscrew implants since it has excellent torsional properties.


Asunto(s)
Tornillos Óseos , Aleaciones Dentales/química , Implantes Dentales , Análisis del Estrés Dental , Métodos de Anclaje en Ortodoncia/instrumentación , Titanio/química , Ensayo de Materiales/instrumentación , Metalurgia , Miniaturización , Fotomicrografía , Estadísticas no Paramétricas , Torsión Mecánica , Difracción de Rayos X
7.
Dent Mater J ; 40(3): 683-688, 2021 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-33518686

RESUMEN

X-ray photoelectron spectroscopy (XPS) is used to analyze 4-META resin and enamel that are debonded at an adhesive interface. The XPS spectra showed two chemical states for Ca: one resulted from Ca of hydroxyapatite and the other, an unknown chemical state, suggested that Ca was chemically bonded with 4-META. We postulate that for a chemical reaction of 4-META and hydroxyapatite, the chemical structure of carboxyl groups will resemble that of calcium phthalate. Hence, calcium phthalate was used as a reference material. Additionally, the spectra obtained from the adhesive interface and the mixture of calcium phthalate with hydroxyapatite particles were compared using peak deconvolution analysis. XPS analysis revealed that the chemical bond of 4-META with enamel resembled the chemical state of Ca in calcium phthalate. Consequently, we suggest that Ca of the enamel and the carboxyl group of 4-META were chelate-bonded at the interface.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos Dentales , Esmalte Dental , Ensayo de Materiales , Metacrilatos , Cementos de Resina
8.
Eur J Oral Sci ; 118(1): 94-9, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20156271

RESUMEN

The contents of volatile adhesive compounds, such as water, solvents, and residual unpolymerized monomers, affect the integrity and durability of adhesive bonding. However, there is no method available that can be used to rapidly assess the residual solvent or water contents of adhesive resins. This study examined the effectiveness of a digital moisture analyzer to measure the volatile compound contents of resins. Five self-etching adhesives and seven experimental light-cured resins prepared with different contents (0, 10, and 20% by weight) of water or solvents (acetone and ethanol) were examined in this study. The resins were prepared using different methods (with and without air blast or light-curing) to simulate the clinical conditions of adhesive application. Resin weight changes (% of weight loss) were determined as the residual volatile compound contents, using the moisture analyzer. After the measurements, the resin films were examined using a scanning electron microscope. The weight changes of the resins were found to depend on the amount of water or solvents evaporating from the resin. Water and solvents were evaporated by air blast or light-curing, but some of the water and solvents remained in the cured resin. The moisture analyzer is easy to operate and is a useful instrument for using to measure the residual volatile compound contents of adhesive resin.


Asunto(s)
Cementos de Resina/química , Compuestos Orgánicos Volátiles/análisis , Acetona/análisis , Aire , Análisis de Varianza , Etanol/análisis , Curación por Luz de Adhesivos Dentales , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Solventes/análisis , Presión de Vapor , Agua/análisis
9.
Eur J Oral Sci ; 118(5): 489-93, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20831583

RESUMEN

This study examined the activity and ability of materials to mineralize teeth in gaps, simulating microleakage between the materials and teeth. Three restorative materials (two glass ionomer cements and a compomer) were used in this study. Cured disks of restoratives were placed over flat human tooth surfaces (enamel and dentin), separated by a standardized 20-µm interfacial space, and stored in water for 24 h or 1 yr. After the water-storage period, the materials were detached from the teeth and the opposing surfaces were examined by scanning electron microscopy (SEM) and electron probe micro analysis (EPMA).Hemispherical-shaped precipitations, composed of minute semicircle plate-like crystals, were observed by SEM on the enamel surface after 1 yr of water storage for glass ionomer cement. The amount of crystal growth with the chemical-cured type of glass ionomer cement was greater than with the dual-cured type of glass ionomer cement. However, there was no crystal formation in the compomer. Moreover, no structural changes were observed on dentin surfaces for any material in water after 1 yr. The elements detected in the crystals by EPMA were calcium (Ca), phosphorus (P), and aluminum (Al). The two glass ionomer cements tested have the ability to induce crystals whose composition might be derived from cured glass ionomers.


Asunto(s)
Compómeros , Filtración Dental/prevención & control , Restauración Dental Permanente/métodos , Cementos de Ionómero Vítreo , Cristalización , Esmalte Dental/ultraestructura , Dentina/ultraestructura , Microanálisis por Sonda Electrónica , Humanos , Curación por Luz de Adhesivos Dentales , Microscopía Electrónica de Rastreo , Auto-Curación de Resinas Dentales
10.
Eur J Oral Sci ; 118(4): 404-10, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20662915

RESUMEN

The purpose of this study was to evaluate the durability of resin-dentin bonds in 10-yr water-storage testing. Resin-dentin bonded bulk specimens were prepared using six commercially available resin adhesives. The resin-dentin bonded specimens were stored in water for 24 h (control group) or for 10 yr (experimental groups). After each storage period, the specimens were sectioned to make specimen beams and then subjected to a microtensile bond test. After the bond test, fractured surfaces were examined by scanning electron microscopy (SEM). In addition, interfacial observation of silver nanoleakage was performed using the backscatter electron mode of SEM. The bond strengths of four of the six adhesive systems tested decreased significantly after 10 yr. However, no significant bond-strength reduction was recorded for the other two systems. The interfacial observations showed water tree propagation in the bonding resin layer as a typical morphological change after aging for five of the six adhesives tested. Water tree propagation may be a symptom of degradation in the resin bonding layer of resin-dentin bonds.


Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios/química , Dentina/ultraestructura , Cementos de Resina/química , Grabado Ácido Dental , Bisfenol A Glicidil Metacrilato/química , Resinas Compuestas/química , Filtración Dental/clasificación , Humanos , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Silanos/química , Dióxido de Silicio/química , Tinción con Nitrato de Plata , Estrés Mecánico , Propiedades de Superficie , Resistencia a la Tracción , Factores de Tiempo , Agua/química , Circonio/química
11.
Dent Mater J ; 29(1): 53-8, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20379013

RESUMEN

This study investigated the corrosion properties of ion implanted nickel-titanium wire (Neo Sentalloy Ionguard) in artificial saliva and fluoride mouth rinse solutions (Butler F Mouthrinse, Ora-Bliss). Non ion implanted nickel-titanium wire (Neo Sentalloy) was used as control. The anodic corrosion behavior was examined by potentiodynamic polarization measurement. The surfaces of the specimens were examined with SEM. The elemental depth profiles were characterized by XPS. Neo Sentalloy Ionguard in artificial saliva and Butler F Mouthrinse (500 ppm) had a lower current density than Neo Sentalloy. In addition, breakdown potential of Neo Sentalloy Ionguard in Ora-Bliss (900 ppm) was much higher than that of Neo Sentalloy although both wires had similar corrosion potential in Ora-Bliss (450 and 900 ppm). The XPS results for Neo Sentalloy Ionguard suggested that the layers consisted of TiO(2) and TiN were present on the surface and the layers may improve the corrosion properties.


Asunto(s)
Aleaciones Dentales , Antisépticos Bucales , Alambres para Ortodoncia , Cariostáticos , Corrosión , Aleaciones Dentales/química , Técnicas Electroquímicas , Fluoruros , Iones , Ensayo de Materiales , Antisépticos Bucales/química , Níquel/química , Nitrógeno , Espectroscopía de Fotoelectrones , Potenciometría , Saliva Artificial , Titanio/química
12.
Nucleosides Nucleotides Nucleic Acids ; 39(1-3): 236-244, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31645174

RESUMEN

Deuterated drugs are valuable in the fields of drug discovery and medicinal chemistry. 2',3',5',5″-tetradeuterated uridine derivatives were synthesised from 2,3,5,5'-selectively tetradeuterated ribose using Sajiki's H-D exchanged Ru/C-H2-D2O-NaOH system and silyl-Hilbert-Johnson methods. The total deuterium content of the tetradeuterated uridines was over 92% using either basic or acidic reaction conditions. These derivatives would be expected as building blocks for the synthesis of deuterium-substituted nucleic acid probes for tracking the pharmacokinetics of nucleic acid drugs.


Asunto(s)
Deuterio/química , Uridina/análogos & derivados , Uridina/síntesis química , Técnicas de Química Sintética , Estructura Molecular
13.
Eur J Oral Sci ; 117(5): 611-7, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19758260

RESUMEN

The purpose of this study was to evaluate the durability of one-bottle self-etching adhesive during long-term water-storage testing. Resin-dentin bonded specimens were prepared using four commercially available one-bottle self-etching adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beam-shaped specimens that were stored in water for 24 h (control group) and 100, 200, and 300 d (experimental groups). After each storage period, the beams were subjected to a microtensile bond test. After the bond test, fractured surfaces were examined using a scanning electron microscope. In addition, interfacial observations of the silver tracer were performed using the secondary and back-scatter modes of the scanning electron microscope. The bond strength of all tested adhesives decreased significantly after 100 or more days in water. The interfacial observations showed an oxygen-inhibition zone as electron lucent in the adhesive-composite border in control specimens, displaying silver impregnation with breakage after aging. The deterioration of the oxygen-inhibition zone in the adhesive-resin composite junction resulted in a decrease in bond strength after 100 d in water for one-bottle self-etching adhesives.


Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo , Materiales Dentales/química , Recubrimientos Dentinarios/química , Dentina/ultraestructura , Bisfenol A Glicidil Metacrilato/química , Filtración Dental/clasificación , Humanos , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Oxígeno/química , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , Cementos de Resina/química , Tinción con Nitrato de Plata , Estrés Mecánico , Propiedades de Superficie , Temperatura , Resistencia a la Tracción , Factores de Tiempo , Agua/química
14.
Biomed Mater Eng ; 19(2-3): 173-8, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19581711

RESUMEN

Finely powdered enamel was used to develop a prosthetic resin composite that has good mechanical properties and no potential to abrade opposing tooth structure. Bovine teeth were ground into powder and then the enamel particles were separated from the powder by centrifugation in bromoform-ethanol solution. The resin matrix consisted of UDMA (60 mole %) and Tri-EDMA (40 mole %). Camphorquinone (0.5 mass %) was added to the monomer as a photo-initiator. Fillers were incorporated directly into the resin matrix in amounts of 80 or 85 mass %. The flexural strength and Vickers hardness (Hv) were measured. The average flexural strength and Hv values for specimens having 85 mass % filler that had been subjected to heat treatment at 100 degrees C after light-curing were 95.2 and 109.8 MPa, respectively, which are higher than those for most commercial prosthetic resin composites. These findings suggest that a novel prosthetic resin composite with good mechanical properties can be made by loading finely powdered enamel into the resin matrix.


Asunto(s)
Esmalte Dental/química , Curación por Luz de Adhesivos Dentales/métodos , Resinas Sintéticas/química , Absorción , Adhesividad , Animales , Materiales Biomiméticos/química , Bovinos , Cristalización/métodos , Dureza , Ensayo de Materiales , Microesferas , Tamaño de la Partícula , Porosidad , Propiedades de Superficie
15.
Dent Mater J ; 28(5): 634-41, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19822996

RESUMEN

This study examined the effect of dentinal water on bonding, comparing one-bottle and two-step self-etching adhesives using microtensile bond test and scanning electron microscope. The bond strength of resin to dentin was measured for wet dentin (control) and dry dentin substrates. Wet dentin is the normal substrate for bond testing, whereas dry dentin was dehydrated in a desiccator at different drying times (5 to 60 min) before bonding. After bond testing, the fractured surfaces were examined. Although no correlation was found for two-step self-etching adhesives, the bond strength of the dry-dentin was significantly increased with the increase in the drying-time for one-bottle adhesives. With increased drying-time, the amount of water-bubbles was decreased for one-bottle adhesives; however, no bubble formation was seen in two-step adhesives in any group. The hydrophilic resin adhesive may entrap the water from dentin by osmosis during and after bonding. This effect may depend on the "hydrophilicity" of adhesives.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Recubrimientos Dentinarios/química , Dentina/química , Metacrilatos/química , Cementos de Resina/química , Grabado Ácido Dental/métodos , Análisis de Varianza , Bisfenol A Glicidil Metacrilato/química , Agua Corporal/química , Resinas Compuestas/química , Filtración Dental/prevención & control , Fracaso de la Restauración Dental , Restauración Dental Permanente/métodos , Análisis del Estrés Dental , Dentina/efectos de los fármacos , Recubrimientos Dentinarios/farmacología , Desecación , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Tercer Molar , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , Estadísticas no Paramétricas
16.
Arch Dermatol Res ; 298(10): 493-8, 2007 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17124586

RESUMEN

Although anti-Fcgamma receptor antibodies (Abs) are detected in various autoimmune diseases, there have been no studies about the anti-Fcgamma receptor Abs in alopecia areata (AA). To detect the anti-Fcgamma receptor Abs in patients with AA and their clinical correlations, Serum samples from 72 patients with AA and 23 normal controls were examined by enzyme-linked immunosorbent assay assessing anti-Fcgamma receptor Ab levels. Anti-Fcgamma receptor I Abs were significantly frequently detected in patients with AA compared with normal controls. Furthermore, the detection of anti-Fcgamma receptor I Abs significantly inversely correlated with the disease duration. These results suggest that anti-Fcgamma receptor I Ab and Fcgamma receptor I play an important role in the regulation of AA, are useful for a marker of the disease prognosis and are worth intense research for the reasonable and specific therapy of AA.


Asunto(s)
Alopecia Areata/sangre , Autoanticuerpos/sangre , Receptores de IgG/inmunología , Adolescente , Adulto , Anciano , Alopecia Areata/patología , Antígenos CD/inmunología , Biomarcadores/sangre , Estudios de Casos y Controles , Progresión de la Enfermedad , Femenino , Proteínas Ligadas a GPI , Humanos , Masculino , Persona de Mediana Edad
17.
Dent Mater ; 23(9): 1051-6, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17178150

RESUMEN

OBJECTIVE: The purpose of this study was to investigate the metallurgical phases in beta-titanium soldered joints prepared by infrared soldering, using the Micro X-ray diffraction technique (Micro-XRD), and to characterize the Vickers hardness in the soldered beta-titanium wires. METHODS: Beta-titanium wires with cross-section dimensions of 0.032in.x0.032in. (TMA, Ormco), and both titanium-based solder (Ti-30Ni-20Cu, Selec) and silver-based solder (Ag-22Cu-17Zn-5Sn, Tomy) were selected. Soldering was performed using infrared radiation (RS-1, Morita) under argon atmosphere. Micro-XRD analyses were performed at room temperature. Micro-XRD spectra were obtained for the boundary region of the soldered beta-titanium wires using 50microm and 10microm diameter analysis regions. Hardness was measured at 30microm intervals from boundary of the diffusion layer and beta-titanium wire. The Kruskal-Wallis test with the Bonferroni and Wilcoxson Mann-Whitney tests for nonparametric means were employed as statistical methods (P<0.05). RESULTS: For both types of soldered beta-titanium samples, the Micro-XRD spectra contained four major peaks for body-centered cubic (bcc) beta-titanium. Additional peaks at about 41 and 45 degrees are attributed to Cu-Ti intermetallic phase(s), which may be metastable under soldering conditions. The diffusion layer had greater hardness than bulk beta-titanium for both types of soldered specimens (P<0.05). SIGNIFICANCE: Soldering of beta-titanium orthodontic wire by infrared radiation may be acceptable for clinical use, since Micro-XRD spectra revealed that both types of soldered specimens largely retained the bcc beta-titanium structure. Further research is needed to investigate the mechanical properties and corrosion behavior of infrared-soldered beta-titanium wire.


Asunto(s)
Soldadura Dental , Alambres para Ortodoncia , Titanio/química , Aleaciones/química , Cobre/química , Difusión , Microanálisis por Sonda Electrónica , Dureza , Humanos , Rayos Infrarrojos , Ensayo de Materiales , Mecánica , Metalurgia , Microespectrofotometría , Níquel/química , Plata/química , Propiedades de Superficie , Estaño/química , Titanio/análisis , Difracción de Rayos X , Zinc/química
18.
J Biomed Mater Res B Appl Biomater ; 79(1): 137-41, 2006 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16615071

RESUMEN

The microstructures and interdiffusion in brazed beta-titanium orthodontic wires were investigated by scanning electron microscopy and electron probe microanalysis, respectively. Beta-titanium wire (Ti-11Mo-6Zr-4Sn) with cross-section dimensions of 0.032 in. x 0.032 in., titanium-based braze alloy (Ti-30Ni-20Cu), and silver-based braze alloy (Ag-22Cu-17Zn-5Sn) were selected for the study. Brazing was performed using infrared radiation (RS-1) under an argon atmosphere. Specimens were etched with two solutions (2.5% HF + 2.5% HNO(3) + 95% H(2)O; 25% HN(4)OH + 30% H(2)O(2) + 45%H(2)O). It was found that the silver-based braze alloy has a eutectic structure. In the diffusion layer between the beta-titanium wire and this silver-based braze alloy, Cu and Ti were enriched on the wire side, and Sn and Ti were enriched on the braze alloy side. The titanium-based braze alloy has a dendritic structure. Beta-titanium wire specimens brazed with the titanium-based braze alloy had a thicker intermediate area compared to the silver alloy; Ti in the diffusion layer had an irregular concentration gradient, and the braze alloy side had higher Ti concentration. The original microstructure of the beta-titanium wire was not altered with the use of either braze alloy. Infrared brazing of beta-titanium orthodontic wire is acceptable for clinical use, since the wire microstructure did not deteriorate with either the titanium-based or silver-based braze alloy. The differing microstructures of the joint regions for the two braze alloys suggest that the joint strengths may also differ.


Asunto(s)
Microanálisis por Sonda Electrónica , Rayos Infrarrojos , Microscopía Electrónica de Rastreo , Alambres para Ortodoncia , Titanio , Soldadura Dental
19.
Dent Mater J ; 25(1): 32-8, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16706294

RESUMEN

Thermally induced liquid-phase deposition method was employed to produce a thin hydroxyapatite (HA) film on a titanium substrate in a metastable calcium phosphate solution. Titanium foil of 100x10x0.02 mm3 was used as a substrate. Prior to HA coating, the substrate was immersed in 5 M NaOH solution at 60 degrees C for 24 hours. Substrate temperature was kept constant at 60 degrees C for 0.5-3 hours by electrical heating with a DC power source in the metastable calcium phosphate solution. An X-ray diffractogram indicated that the film deposited on the titanium substrate was composed of HA. The amount of HA deposited increased with increase in heating time. These results suggested that a uniform HA film can be formed by simple chemical and thermal treatments. Based on the results of this study, this technique seemed to be useful for producing uniform HA coatings on complex-shaped and porous dental implants.


Asunto(s)
Materiales Biocompatibles Revestidos/química , Implantes Dentales , Durapatita/química , Titanio/química , Calor , Propiedades de Superficie , Factores de Tiempo
20.
Angle Orthod ; 76(4): 705-11, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16808581

RESUMEN

The purpose of this study was to provide a quantitative assessment of galvanic corrosion behavior of orthodontic archwire alloys coupled to orthodontic bracket alloys in 0.9% NaCl solution and to study the effect of surface area ratios. Two common bracket alloys, stainless steels and titanium, and four common wire alloys, nickel-titanium (NiTi) alloy, beta-titanium (beta-Ti) alloy, stainless steel, and cobalt-chromium-nickel alloy, were used. Three different area ratios, 1:1, 1:2.35, and 1:3.64, were used; two of them assumed that the multibracket appliances consists of 14 brackets and 0.016 inch of round archwire or 0.016 x 0.022 inch of rectangular archwire. The galvanic current was measured for 3 successive days using zero-impedance ammeter. When the NiTi alloy was coupled with Ti (1:1, 1:2.35, and 1:3.64 of the surface area ratio) or beta-Ti alloy was coupled with Ti (1:2.35 and 1:3.64 of the surface area ratio), Ti initially was the anode and corroded. However, the polarity reversed in 1 hour, resulting in corrosion of the NiTi or beta-Ti. The NiTi alloy coupled with SUS 304 or Ti exhibited a relatively large galvanic current density even after 72 hours. It is suggested that coupling SUS 304-NiTi and Ti-NiTi may remarkably accelerate the corrosion of NiTi alloy, which serves as the anode. The different anode-cathode area ratios used in this study had little effect on galvanic corrosion behavior.


Asunto(s)
Aleaciones Dentales/química , Soportes Ortodóncicos , Alambres para Ortodoncia , Aleaciones de Cromo/química , Corrosión , Materiales Dentales/química , Impedancia Eléctrica , Electroquímica , Humanos , Ensayo de Materiales , Níquel/química , Diseño de Aparato Ortodóncico , Cloruro de Sodio/química , Acero Inoxidable/química , Propiedades de Superficie , Factores de Tiempo , Titanio/química
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA