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1.
Science ; 370(6512): 37-38, 2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-33004503
2.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 34(9): 1170-1176, 2020 Sep 15.
Artigo em Chinês | MEDLINE | ID: mdl-32929912

RESUMO

Objective: To investigate the effects of three-dimensional (3D) printed Ti6Al4V-4Cu alloy on inflammation and osteogenic gene expression in mouse bone marrow mesenchymal stem cells (BMSCs) and mouse mononuclear macrophage line RAW264.7. Methods: Ti6Al4V and Ti6Al4V-4Cu alloys were prepared by selective laser melting, and the extracts of the two materials were prepared according to the biological evaluation standard of medical devices. The effects of two kinds of extracts on the proliferation of mouse BMSCs and mouse RAW264.7 cells were detected by cell counting kit 8 method. After co-cultured with mouse BMSCs for 3 days, the expression of osteogenesis- related genes [collagen type Ⅰ (Col-Ⅰ), alkaline phosphatase (ALP), Runx family transcription factor 2 (Runx-2), osteoprotegerin (OPG), and osteopontin (OPN)] were detected by real-time fluorescence quantitative PCR. After co-cultured with mouse RAW264.7 cells for 1 day, the expressions of inflammation-related genes [interleukin 4 (IL-4) and nitric oxide synthase 2 (iNOS)] were detected by real-time fluorescence quantitative PCR, and the supernatants of the two groups were collected to detect the secretion of vascular endothelial growth factor a (VEGF-a) and bone morphogenetic protein 2 (BMP-2) by ELISA. The osteogenic conditioned medium were prepared with the supernatants of the two groups and co-cultured with BMSCs for 3 days. The expressions of osteogenesis-related genes (Col-Ⅰ, ALP, Runx-2, OPG, and OPN) were detected by real-time fluorescence quantitative PCR. Results: Compared with Ti6Al4V alloy extract, Ti6Al4V-4Cu alloy extract had no obvious effect on the proliferation of BMSCs and RAW264.7 cells, but it could promote the expression of OPG mRNA in BMSCs, reduce the expression of iNOS mRNA in RAW264.7 cells, and promote the expression of IL-4 mRNA. It could also promote the secretions of VEGF-a and BMP-2 in RAW264.7 cells. Ti6Al4V-4Cu osteogenic conditioned medium could promote the expressions of Col-Ⅰ, ALP, Runx-2, OPG, and OPN mRNAs in BMSCs. The differences were all significant ( P<0.05). Conclusion: 3D printed Ti6Al4V-4Cu alloy can promote RAW264.7 cells to secret VEGF-a and BMP-2 by releasing copper ions, thus promoting osteogenesis through bone immune regulation, which lays a theoretical foundation for the application of metal prosthesis.


Assuntos
Ligas , Osteogênese , Animais , Células da Medula Óssea , Proteína Morfogenética Óssea 2/metabolismo , Diferenciação Celular , Células Cultivadas , Regulação da Expressão Gênica , Camundongos , Titânio , Fator A de Crescimento do Endotélio Vascular/metabolismo
3.
Rev. cient. odontol ; 8(2): e018-e018, mayo-ago. 2020. ilus, tab
Artigo em Espanhol | LILACS, LIPECS | ID: biblio-1119296

RESUMO

Antecedentes: Las limas rotatorias de níquel-titanio con tratamiento termomecánico se desarrollaron para permitir una mayor flexibilidad al instrumentar los conductos radiculares. Los instrumentos permitieron a los operadores tratar las curvaturas de los conductos con mayor facilidad. Los fabricantes están tratando de producir limas que funcionen de manera más eficiente y segura. Conocer las propiedades de las limas comercializadas es especialmente importante porque ayuda a elegir un sistema de lima apropiado. El objetivo de este estudio fue evaluar la flexibilidad de tres limas diferentes de níquel-titanio (NiTi) con tratamiento termomecánico en dos puntos diferentes. Materiales y métodos: Se midió la flexibilidad de tres limas NiTi con tratamiento termomecánico (ProTaper Gold, 2Shape y V-Taper Fanta Gold). Cada lima fue sujetada a 3 mm y 7 mm (n = 10/longitud/lima) y se utilizó una máquina de ensayo universal para doblarla a una fuerza máxima. Todos los datos fueron analizados estadísticamente por análisis de varianza de una vía y prueba de Tukey post hoc (p = 0,05) para determinar cualquier diferencia significativa. Resultados: Se halló diferencias estadísticamente significativas (p < 0,05). En general, V-Taper Fanta Gold fue la más rígida, ProTaper Gold mostró los mayores valores de fuerza y su deformación fue significativamente más flexible. Conclusión: Las limas ProTaper Gold mostraron una mayor flexibilidad en comparación con las otras limas estudiadas. (AU)


Background: Nickel-titanium rotary files with thermomechanical treatment were developed to allow greater flexibility when instrumenting the root canals. The instruments allowed operators to deal with duct curvatures more easily. Manufacturers are trying to produce files that work better efficiently and safely. Knowing the properties of marketed files is especially important in helping you choose an appropriate file system. The objective of this study was to evaluate the flexibility of three different nickel-titanium (NiTi) files with thermomechanical treatment at two different points along the file. Materials and methods: The flexibility of three NiTi files with thermomechanical treatment (Protaper Gold, 2Shape and V-Taper Fanta Gold) was measured. Each file was clamped at 3 mm and 7 mm (n = 10 / length / file) and a universal testing machine was used to bend the files to a maximum strength. All data were statistically analyzed by one-way analysis of variance and post-hoc Tukey test (P = 0.05) to determine any significant differences. Results: There were statistically significant differences (P <0.05). In general, V-Taper Fanta Gold was the most rigid, Protaper Gold showed the highest values of force and deformation was significantly more flexible. Conclusión: Protaper Gold files showed greater flexibility compared to the other files studied. (AU)


Assuntos
Titânio , Maleabilidade , Instrumentos Odontológicos , Ligas , Níquel
4.
Science ; 369(6505): 773-774, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32792384
5.
Bone Joint J ; 102-B(7_Supple_B): 116-121, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32600200

RESUMO

AIMS: This study aimed to determine if macrophages can attach and directly affect the oxide layers of 316L stainless steel, titanium alloy (Ti6Al4V), and cobalt-chromium-molybdenum alloy (CoCrMo) by releasing components of these alloys. METHODS: Murine peritoneal macrophages were cultured and placed on stainless steel, CoCrMo, and Ti6Al4V discs into a 96-well plate. Cells were activated with interferon gamma and lipopolysaccharide. Macrophages on stainless steel discs produced significantly more nitric oxide (NO) compared to their control counterparts after eight to ten days and remained elevated for the duration of the experiment. RESULTS: On stainless steel, both nonactivated and activated cell groups were shown to have a significant increase in metal ion release for Cr, Fe, and Ni (p < 0.001, p = 0.002, and p = 0.020 respectively) compared with medium only and showed macrophage-sized corrosive pits on the stainless steel surface. On titanium alloy discs there was a significant increase in aluminum (p < 0.001) among all groups compared with medium only. CONCLUSION: These results indicated that macrophages were able to attach to and affect the oxide surface of stainless steel and titanium alloy discs. Cite this article: Bone Joint J 2020;102-B(7 Supple B):116-121.


Assuntos
Prótese Articular , Macrófagos/química , Aço Inoxidável , Titânio , Vitálio , Ligas , Animais , Sobrevivência Celular , Cromo/análise , Meios de Cultura , Íons , Ferro/análise , Camundongos , Microscopia Eletrônica de Varredura , Níquel/análise , Óxido Nítrico/análise
6.
J Endod ; 46(10): 1478-1484, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32710894

RESUMO

INTRODUCTION: The aim of this study was to evaluate under scanning electronic microscopy the enlargement and deformation of the apical foramen of curved mesiobuccal roots with both reciprocating and rotary single-file systems made of a newly heat-treated alloy through the use of Reciproc Blue (REC Blue; VDW, Munich, Germany) and XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland). METHODS: Forty mesiobuccal roots of mandibular and maxillary molars presenting a curvature ranging from 20°-40° were used in this study. The apical foramens were initially scanned with a scanning electronic microscope under 200× magnification. Roots were divided into 2 groups (n = 20): the REC Blue group instrumented with the REC Blue system and the XPS group instrumented with the XPS system. Both groups were instrumented at the foramen. The apical foramens were scanned after root canal preparation. The area, circularity, and ratio of the Feret diameters were calculated from each image. The Kolmogorov-Smirnov, Mann-Whitney, and Wilcoxon tests were used for statistical analysis (P ≤ .05). RESULTS: The area of the foramen increased significantly after canal shaping with REC Blue and XPS. The variation of the area was significantly greater with XPS. However, there were no significant differences in circularity and the ratio of the Feret diameters with both instruments. CONCLUSIONS: No transportation was found when using REC Blue and XPS. The newly heat-treated nickel-titanium alloy did not promote deformation of the apical foramen in curved canals.


Assuntos
Níquel , Ápice Dentário/diagnóstico por imagem , Ligas , Cavidade Pulpar/diagnóstico por imagem , Desenho de Equipamento , Temperatura Alta , Preparo de Canal Radicular , Titânio
7.
J Endod ; 46(10): 1485-1494, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32721485

RESUMO

INTRODUCTION: This study aimed to compare the mechanical and metallurgical properties and shaping ability of different rotary systems using a multimethod approach. METHODS: New NeoNiti A1 (Neolix SAS, Châtres-La-Forêt, France), HyFlex EDM One File (Coltène/Whaledent, Altstätten, Switzerland), ProTaper Gold F2 (Dentsply Maillefer, Ballaigues, Switzerland), and ProTaper Universal F2 (Dentsply Maillefer) rotary instruments were tested regarding cyclic fatigue, torsional resistance, design, and morphologic characteristics using scanning electron microscopy, metal alloy characterization using differential scanning calorimetry, and energy-dispersive X-ray spectroscopy. Additionally, their shaping ability on the preparation of 48 canals of maxillary molars was evaluated using micro-computed tomographic technology. Mechanical and metallurgical analyses were compared using analysis of variance post hoc Tukey tests, whereas the independent Student t test was used to compare the shaping ability of the ProTaper systems or the thermomechanically treated instruments. The significance level was set at 5%. RESULTS: The highest cyclic fatigue was observed with the NeoNiti and HyFlex EDM instruments (P > .05), whereas HyFlex EDM had the highest angular rotation to fracture (P < .05). Scanning electron microscopic/energy-dispersive X-ray spectroscopic analyses confirmed similarities in the instruments' design and an almost equiatomic composition of the systems. Differential scanning calorimetry showed that ProTaper Gold had higher transformation temperatures than ProTaper Universal, whereas a similar transformation was observed between NeoNiti and HyFlex. Micro-computed tomographic analysis revealed that, despite the fact that none of the systems was able to prepare all root canal walls, no statistical differences were observed in either ProTaper systems (P > .05) or the thermomechanically treated instruments (P > .05). CONCLUSIONS: Apart from differences in the mechanical tests and metallurgical characterization, systems with comparable instrument dimensions and preparation protocols showed a similar percentage of untouched surface areas in the root canal preparation of maxillary molars.


Assuntos
Níquel , Titânio , Ligas , Ligas Dentárias , Desenho de Equipamento , Falha de Equipamento , França , Humanos , Teste de Materiais , Preparo de Canal Radicular , Estresse Mecânico
8.
PLoS One ; 15(7): e0234563, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32673336

RESUMO

The archaeometallurgical and archaeological research carried out in Anatolia has provided numerous examples of diverse alloying practices representing different levels of societal interaction, from the extraction of ores to the trade of finished goods and high level gift exchange among elites. While discussions abound about the exploitation of mines, mining settlements, possible origins of artifacts, resources of copper, arsenic, and especially tin to improve our knowledge about Anatolian Bronze Age mining and metallurgy, uncommon alloying practices including the use of antimony, nickel, or lead have long remained in the shadows of scholarly research. With the aim of bringing attention to the diversity in alloying practices in Anatolian metallurgy, this article focuses on the use of antimony through an appraisal of archaeological and textual evidence from Bronze Age Anatolia. Archaeometric data from several Early Bronze Age sites are re-examined alongside new data emerging from Resuloglu (Çorum, Turkey) to explain the reduction of the variety of alloy types used. Portable-XRF analysis of artifacts from Resuloglu and mineralogical analysis of an antimony-bearing ore fragment present evidence of use of antimony at the region during the Early Bronze Age. This period is followed by disappearance of antimony in material record until the Iron Age, while textual records weakly refer to its circulation within the region. This paper considers geological, technological, and socio-economic factors to explain why the use of antimony alloys falls dormant after the Early Bronze Age. The political and economic change towards centralization over geological and technological factors is proposed as an explanation.


Assuntos
Ligas/história , Metalurgia/história , Antimônio/química , Arqueologia/métodos , História Antiga , Humanos , Mineração/história , Mineração/tendências , Turquia
9.
Environ Pollut ; 265(Pt A): 114892, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526632

RESUMO

More than 40% of the crystalline silicon has been wasted as silicon cutting waste (SCW) during the wafer production process. This waste not only leads to resource wastage but also causes environmental burden. In this paper, SCW produced by the diamond-wire sawing process was recycled by Al-Si alloying process. Cryolite was introduced to the reaction system to dissolve the SiO2 layer existed on the surface of the Si particles in SCW. Alloys with 12.02 wt% of Si were prepared and the mechanism of the alloying process was investigated in detail. The Si-Al-cryolite system and SiO2-Al-cryolite system were studied individually to analyze the reaction process and transferring behavior of Si and SiO2 in SCW. The SiO2 shell was firstly transformed into Si-O-F ions. Then the Si-O-F ions diffused to the reaction interface by the effect of the concentration gradient and were reduced to Si by the aluminothermic reduction reaction: 4Al (l) + 3SiO2 (dissolved in the melt) = 3Si (Al)+ 2Al2O3 (dissolved in the melt). Then the internal Si particles were released into cryolite after the dissolution of SiO2 and transferred to the reaction interface by the effect of gravity. The influences of the mass ratio of Al/SCW and agitation modes on the Si content of the alloys and the Si recovery ratio in SCW were investigated. With the increase of the mass ratio of Al/SCW from 2.2 to 6.5, the Si recovery ratio in SCW increased from 44.08% to 69.05%, but the silicon content of the alloys decreased from 16.06 wt% to 8.83 wt%. Agitation can effectively improve the smelting effect during smelting by which the silicon content of the alloys and the Si recovery ratio in SCW increased from 12.02 wt% and 64.25% to 13.17 wt% and 69.46%, respectively.


Assuntos
Ligas , Silício , Reciclagem , Dióxido de Silício , Fluoreto de Sódio
10.
Chemosphere ; 257: 127182, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32534293

RESUMO

The impact of offshore constructions on the marine environment is unknown in many aspects. The application of Al- and Zn-based galvanic anodes as corrosion protection results in the continuous emission of inorganic matter (e.g. >80 kg Al-anode material per monopile foundation and year) into the marine environment. To identify tracers for emissions from offshore wind structures, anode materials (Al-based and Zn-based) were characterized for their elemental and isotopic composition. An acid digestion and analysis method for Al and Zn alloys was adapted and validated using the alloy CRMs ERM®-EB317 (AlZn6CuMgZr) and ERM®-EB602 (ZnAl4Cu1). Digests were measured for their elemental composition by ICP-MS/MS and for their Pb isotope ratios by MC ICP-MS. Ga and In were identified as potential tracers. Moreover, a combined tracer approach of the elements Al, Zn, Ga, Cd, In and Pb together with Pb isotope ratios is suggested for a reliable identification of offshore-wind-farm-induced emissions. In the Al anodes, the mass fractions were found to be >94.4% of Al, >26200 mg kg-1 of Zn, >78.5 mg kg-1 of Ga, >0.255 mg kg-1 of Cd, >143 mg kg-1 of In and >6.7 mg kg-1 of Pb. The Zn anodes showed mass fractions of >2160 mg kg-1 of Al, >94.5% of Zn, >1.31 mg kg-1 of Ga, >254 mg kg-1 of Cd, >0.019 mg kg-1 of In and >14.1 mg kg-1 of Pb. The n(208Pb)/n(206Pb) isotope ratios in Al anodes range from 2.0619 to 2.0723, whereas Zn anodes feature n(208Pb)/n(206Pb) isotope ratios ranging from 2.0927 to 2.1263.


Assuntos
Monitoramento Ambiental , Metais Pesados/análise , Poluentes Químicos da Água/análise , Ligas , Alumínio , Corrosão , Eletrodos , Isótopos/análise , Espectrometria de Massas em Tandem , Vento
11.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 34(6): 671-675, 2020 Jun 15.
Artigo em Chinês | MEDLINE | ID: mdl-32538554

RESUMO

Objective: To evaluate the effectiveness of nitinol memory alloy two foot fixator combined with Kirschner wire in the treatment of trans-scaphoid perilunate dislocation. Methods: Between September 2011 and October 2018, 17 patients with trans-scaphoid perilunate dislocation were treated with nitinol memory alloy two foot fixator and Kirschner wire. There were 12 males and 5 females, with an average age of 32.6 years (range, 23-52 years). The disease duration was 8 hours to 9 days, with an average of 6.5 days. The causes of injury included 6 cases of falling injury, 4 cases of traffic accident injury, 3 cases of stress injury of wrist caused by sports, 2 cases of violent injury of wrist caused by machine impact, 1 case of military training injury, and 1 case of other injury. One case was complicated with nerve injury. According to Herbert's classification, all the fractures were type B4. At 1 week before operation, 3 months, 6 months after operation and last follow-up, the wrist function was evaluated according to the Krimmer scale score. Results: All the 17 patients were followed up 10.5-48 months, with an average of 18.6 months. There was no loosening or infection of the internal fixator, no necrosis of the scaphoid and lunate. The periosteal dislocations of the patients were well reduced and the scaphoid fractures all healed. The healing time was 4-18 months, with an average of 11.3 months. The Krimmer wrist scores were 37.5±4.4, 61.3±7.2, 83.3±9.3, 87.3±8.2 at 1 week before operation, 3 months, 6 months after operation and last follow-up, respectively. The Krimmer wrist score at each time point after operation was significantly improved when compared with that before operation ( P<0.05), and at 6 months after operation and last follow-up than at 3 months after operation ( P<0.05). There was no significant difference between at 6 months and last follow-up ( P>0.05). At last follow-up, the Krimmer wrist function was excellent in 13 cases, good in 2 cases, fair in 1 case, poor in 1 case, and the excellent and good rate was 88.23%. Conclusion: Nitinol memory alloy two foot fixator combined with Kirschner wire in the treatment of trans-scaphoid periosteal dislocation has definite effectiveness, simple operation, and good recovery of wrist function after operation.


Assuntos
Ligas , Fios Ortopédicos , Fixação Interna de Fraturas , Fraturas Ósseas , Luxações Articulares , Osso Escafoide , Adulto , Ligas/uso terapêutico , Fios Ortopédicos/normas , Feminino , Fixação Interna de Fraturas/normas , Fraturas Ósseas/cirurgia , Humanos , Luxações Articulares/cirurgia , Masculino , Pessoa de Meia-Idade , Osso Escafoide/cirurgia , Resultado do Tratamento , Adulto Jovem
12.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 34(6): 676-682, 2020 Jun 15.
Artigo em Chinês | MEDLINE | ID: mdl-32538555

RESUMO

Objective: To summarize the effectiveness of nitinol memory alloy two foot fixator with autologous cancellous bone grafting in treating old scaphoid fracture and nonunion. Methods: Between January 2013 and January 2017, 11 patients of old scaphoid fracture and nonunion were treated with nitinol memory alloy two foot fixator and autologous cancellous bone grafting. All patients were male with an average age of 26.1 years (range, 18-42 years). The fractures were caused by sport in 3 cases, falling in 7 cases, and a crashing object in 1 case. The interval between injury and operation was 6-18 months (mean, 8.9 months). Postoperative outcome measures included operation time, fracture healing time, grip strength, range of motion (ROM) of flexion, extension, ulnar deviation, and radial deviation, Mayo score, visual analogue scale (VAS) score, and the Disabilities of the Arm, Shoulder, and Hand (DASH) score. Results: The operation time was 35-63 minutes (mean, 48 minutes). All incisions had primary healing with no infection and loosening or breakage of internal fixator. All patients were followed up 12-30 months (mean, 20.7 months). X-ray films showed that fracture healing was achieved in all patients with an average time of 15 weeks (range, 12-25 weeks). All internal fixators were removed after 10-12 months of operation (mean, 11.2 months). At last follow-up, the grip strength, ROMs of flexion, ulnar deviation, and radial deviation were superior to those before operation ( P<0.05), no significant difference was found in ROM of extension between pre- and post-operation ( t=0.229, P=0.824). There were significant differences in above indexes between affected and normal sides ( P<0.05). At last follow-up, the Mayo, VAS, DASH scores were also significantly superior to those before operation ( P<0.05). Conclusion: For the old scaphoid fracture and nonunion, Ni-Ti arched shape-memory alloy fixator and autologous cancellous bone grafting can obtain good effectiveness, which is an effective treatment.


Assuntos
Ligas , Transplante Ósseo , Osso Esponjoso , Fixação Interna de Fraturas , Fraturas não Consolidadas , Osso Escafoide , Adolescente , Adulto , Ligas/química , Transplante Ósseo/métodos , Osso Esponjoso/cirurgia , Fixação Interna de Fraturas/normas , Fraturas não Consolidadas/cirurgia , Humanos , Masculino , Amplitude de Movimento Articular , Osso Escafoide/cirurgia , Resultado do Tratamento , Adulto Jovem
13.
PLoS One ; 15(6): e0234774, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32569283

RESUMO

We developed and describe a differential scanning calorimetry method for calculating the initial crystallinity, change of crystallinity and crystallinity percentage of amorphous metal alloys as a function of temperature. Using thermodynamic enthalpies of amorphous, crystalline and partially devitrified specimens, our methodology is capable of determining crystallinity percentages as low as a few percent. Moreover, the linear relationship between the set (pre-determined) and calculated crystallinities of experimental samples indicates that there is no need to prepare calibration samples before measuring the crystallinity percentage of target samples. This technique also eliminates the need for expensive in situ accessories, such as those required in electron microscopy. Thus, the technique is highly relevant as a primary technique for characterization of devitrification behavior in amorphous materials.


Assuntos
Ligas/química , Varredura Diferencial de Calorimetria , Cristalografia por Raios X , Temperatura
14.
PLoS One ; 15(6): e0234981, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32574186

RESUMO

The corrosion behavior of an AZ91D magnesium alloy was investigated under a heterogeneous electrolyte layer by using electrochemical methods and surface analysis techniques. Dynamic polarization curves and morphological characterization were obtained at the center and near the edge zones under the electrolyte layer. The influence of the gas/liquid/solid three-phase boundary zone (TPB) on the corrosion behavior of the AZ91D magnesium alloy was discussed. The corrosion rate changed more significantly near the TPB zone than that at the other zones. The AZ91D alloy exhibited the characteristics of filiform corrosion together with shallow pitting corrosion. Different from the randomly distributed shallow pits, the filiform corrosion preferred to initiate near the TPB region and then progressively expanded adjacent to the edge of the electrolyte layer. The TPB zone played a vital role in determining the corrosion location, the corrosion morphologies and the corrosion rate of the magnesium alloy by influencing the mass transport process of carbon dioxide.


Assuntos
Ligas/química , Eletrólitos/química , Magnésio/química , Corrosão , Técnicas Eletroquímicas/instrumentação , Eletrodos , Propriedades de Superfície , Difração de Raios X
15.
Dent Mater ; 36(7): 945-958, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32475749

RESUMO

OBJECTIVE: Titanium and its alloys are widely used for dental and medical biomaterials due to their excellent mechanical and biological advantages. After the introduction of direct laser metal sintering (DLMS) 3D printing technology and its use over conventional machine-cut processes, questions remain regarding whether 3D-printed titanium (alloy) devices have similar biological properties to machine-cut counterparts for dental applications. Thus, this work focuses on comparing the biological activities of machine-cut and 3D-printed specimens after optimizing the DLMS 3D-printing conditions in terms of the mechanophysical characteristics. METHODS: The DLMS 3D-printing (as a function of the laser spacing from 30-100µm) and post-surface treatment (as-given or sand-blasted) conditions were optimized using medical-grade Ti-6Al-4V powders in terms of the inner pore amount, mechanical properties, roughness and hydrophilicity. Then, the initial cell adhesion of the optimized DLMS 3D-printed Ti-6Al-4V specimen was compared with that of the machine-cut Ti-6Al-4V specimen against human dermal fibroblasts (hDFs) and mesenchymal stem cells (hMSCs), which are representative of direct-contact cell types of orofacial mucosa and bone, respectively. hMSC differentiation on the specimens was conducted for up to 21 days to measure the osteogenic gene expression and biomineralization. RESULTS: Laser spacings of 30-40µm had fewer inner defects and consequently a higher three-point flexural strength and elastic modulus compared to other larger laser spacings. Depending on the span width (0.3-1mm) in the lattice architecture, the elastic modulus of the 3D-printed cuboid specimen can be further controlled (up to ∼30 times). The sand-blasted specimens after 3D printing revealed lower surface roughness and higher hydrophilicity compared to the as-3D printed specimen, which were considered optimal conditions for biological study. Initial hDF and hMSC adhesion for 12 hr and hMSC differentiation on the surface were comparable between the sand-blasted 3D-printed and machine-cut specimens in terms of adherent cell numbers, vinculin intensity, osteogenic gene expression and biomineralization. SIGNIFICANCE: The optimized DLMS 3D-printed Ti-6Al-4V specimen had similar biological properties to those of the machine-cut counterpart, suggesting the potential usefulness of 3D printing technology for a wide range of dental applications.


Assuntos
Ligas , Titânio , Materiais Biocompatíveis , Humanos , Teste de Materiais , Osteogênese , Impressão Tridimensional , Propriedades de Superfície
16.
Khirurgiia (Mosk) ; (4): 61-64, 2020.
Artigo em Russo | MEDLINE | ID: mdl-32352670

RESUMO

A 93-year-old patient underwent endoscopic treatment of perforated duodenal ulcer after previous laparoscopic suturing complicated by failure of sutured defect. A self-expanding nitinol stent with partial polyurethane coating was used. Positive effect of the treatment was noted. Further study of this method and its clinical introduction in case of favorable results can significantly reduce the incidence of complications and mortality in patients with perforated gastroduodenal ulcers.


Assuntos
Úlcera Duodenal/cirurgia , Úlcera Péptica Perfurada/cirurgia , Idoso de 80 Anos ou mais , Ligas , Materiais Revestidos Biocompatíveis , Duodenoscopia , Gastroscopia , Humanos , Laparoscopia/efeitos adversos , Poliuretanos , Implantação de Prótese , Reoperação , Stents Metálicos Autoexpansíveis , Técnicas de Sutura/efeitos adversos
17.
J Contemp Dent Pract ; 21(1): 1, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32381792

RESUMO

Root canal treatment is one of the most challenging practices in dentistry as the complexity and the variability of the endodontic space can often lead the operator to create false trajectories or missing canals. The technical advances in the development of even more efficient and resistant endodontic instrument reached important results in the last few years with the adoption of NiTi alloys and thermal treatments, which could increase the flexibility and the resistance of the instruments.1,2.


Assuntos
Endodontia , Ligas , Ligas Dentárias , Assistência Odontológica , Humanos , Tratamento do Canal Radicular
18.
Dent Mater J ; 39(5): 825-833, 2020 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-32418951

RESUMO

This study evaluated bond strengths of three commercial veneering porcelains to experimental cast titanium-chromium (Ti-Cr) alloy and commercially pure titanium (cp-Ti) via three-point bending test. After the bending test, the fractured specimens were analyzed using an electron probe microanalyzer (EPMA). The Ti-Cr specimens showed lower bond strengths than the cp-Ti specimens, irrespective of the layering porcelain material; however, all the strengths exceeded the minimum requirement of ISO 9693-1:2012 (>25 MPa). EPMA revealed that titanium and/or chromium elements were detected on the debonded porcelain surface of the Ti-Cr and cp-Ti specimens in the case of the higher bond strength. Contrastingly, the residual porcelain was retained on the metallic surface in the case of the lower bond strength. Although porcelain bonding to the titanium alloy is influenced by porcelain type, the Ti-Cr alloy could be feasible for porcelain-fused-to-metal restorations.


Assuntos
Colagem Dentária , Porcelana Dentária , Ligas , Cromo , Teste de Materiais , Ligas Metalo-Cerâmicas , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Titânio
19.
Nature ; 580(7802): 188-189, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32269348
20.
Cancer Radiother ; 24(2): 128-134, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32224107

RESUMO

PURPOSE: Shielding disks play an important role in intraoperative electron radiation therapy, and different designs are currently used in clinical practice. This paper investigates the dosimetric impact of the shielding disk used during intraoperative electron radiation therapy (IOERT). MATERIALS AND METHODS: This paper focuses on the study of four shielding disks types that have been used in our clinic: Aluminum (Al)/Lead (Pb), PMMA/Copper(Cu)/PMMA, Aluminum (Al)/Copper (Cu) and Aluminum (Al)/Steel with their specific thicknesses. The theoretical study was conducted with the EGSnrc Monte Carlo (MC) code. On the other hand, the measurements were carried out with gafchromic films for the four shielding disks for the same setup inside the water phantom. Finally, a comparison of the simulated and measured PDD curves was performed for the four material combinations. RESULTS: MC simulation and gafchromic measurements illustrated that dose values under the four shielding disks types were close to 0, whereas the backscattering enhancement of the disks were 103% with Al/Pb shielding disk, 102% with Al/Steel shielding disk, 102% with Al/Cu shielding disk, 95% with PMMA/Cu/PMMA shielding disk. The PDDs values of the gafchromic films in front of the disks were: 107%, 105%, 104%, and 94% for the Al/Pb, Al/Steel, Al/Cu, and PMMA/Cu/PMMA disks respectively. CONCLUSIONS: The dose values above and under the shielding disks were acceptable for the four studied shielding types. Demonstrated it is possible to use any of them clinically, while the best shielding disk was the Al/Pb since it has minimum thickness and a small backscatter enhancement.


Assuntos
Elétrons/uso terapêutico , Cuidados Intraoperatórios/instrumentação , Método de Monte Carlo , Órgãos em Risco , Proteção Radiológica/instrumentação , Ligas , Alumínio , Neoplasias da Mama/radioterapia , Cobre , Desenho de Equipamento , Feminino , Coração , Humanos , Cuidados Intraoperatórios/métodos , Pulmão , Aceleradores de Partículas , Imagens de Fantasmas , Dosagem Radioterapêutica , Costelas , Espalhamento de Radiação , Aço
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