Algumas reflexões sobre o mapeamento geotécnico

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Electrochemical Behavior Of Bioactive Coatings On Cp-ti Surface For Dental Application

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The surface characteristics and electrochemical properties of bioactive coatings produced by plasma electrolytic oxidation (PEO) with calcium, phosphorous, silicon and silver on commercially pure titanium were evaluated. PEO treatment produced a porous oxide layer, which improved the surface topography, and enriched the surface chemistry with bioactive elements, responsible for mimicking bone surface. The surfaces with higher calcium concentration presented antibacterial and biocompatibility properties with better responses for corrosion and barrier properties, due to the presence of rutile crystalline structure. PEO may be a promising surface treatment option to improve the electrochemical behavior of dental implants mitigating treatment failures. (C) 2015 Elsevier Ltd. All rights reserved.100133146Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)NIH [AR064005]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CAPES [11838-13-2

Surface-treated Commercially Pure Titanium For Biomedical Applications: Electrochemical, Structural, Mechanical And Chemical Characterizations

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Modified surfaces have improved the biological performance and biomechanical fixation of dental implants compared to machined (polished) surfaces. However, there is a lack of knowledge about the surface properties of titanium (Ti) as a function of different surface treatment. This study investigated the role of surface treatments on the electrochemical, structural, mechanical and chemical properties of commercial pure titanium (cp-Ti) under different electrolytes. Cp-Ti discs were divided into 6 groups (n = 5): machined (M-control); etched with HCl + H2O2 (Cl), H2SO4 + H2O2 (5); sandblasted with Al2O3 (Sb), Al2O3 followed by HCl + H2O2 (SbCl), and Al2O3 followed by H2SO4 + H2O2 (SbS). Electrochemical tests were conducted in artificial saliva (pHs 3; 6.5 and 9) and simulated body fluid (SBF-pH 7.4). All surfaces were characterized before and after corrosion tests using atomic force microscopy, scanning electron microscopy, energy dispersive microscopy, X-ray diffraction, surface roughness, Vickers microhardness and surface free energy. The results indicated that Cl group exhibited the highest polarization resistance (R-p) and the lowest capacitance (Q) and corrosion current density (I-corr) values. Reduced corrosion stability was noted for the sandblasted groups. Acidic artificial saliva decreased the R-p values of cp-Ti surfaces and produced the highest I-corr values. Also, the surface treatment and corrosion process influenced the surface roughness, Vickers microhardness and surface free energy. Based on these results, it can be concluded that acid-etching treatment improved the electrochemical stability of cp-Ti and all treated surfaces behaved negatively in acidic artificial saliva. (C) 2016 Elsevier B.V. All rights reserved.65251261State of Sao Paulo Research Foundation (FAPESP) [2013/24112-2, 2013/08451-1]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Tribocorrosion Behavior Of Biofunctional Titanium Oxide Films Produced By Micro-arc Oxidation: Synergism And Mechanisms.

Dental implants, inserted into the oral cavity, are subjected to a synergistic interaction of wear and corrosion (tribocorrosion), which may lead to implant failures. The objective of this study was to investigate the tribocorrosion behavior of Ti oxide films produced by micro-arc oxidation (MAO) under oral environment simulation. MAO was conducted under different conditions as electrolyte composition: Ca/P (0.3M/0.02M or 0.1M/0.03M) incorporated with/without Ag (0.62g/L) or Si (0.04M); and treatment duration (5 and 10min). Non-coated and sandblasted samples were used as controls. The surfaces morphology, topography and chemical composition were assessed to understand surface properties. ANOVA and Tukey׳s HSD tests were used (α=0.05). Biofunctional porous oxide layers were obtained. Higher Ca/P produced larger porous and harder coatings when compared to non-coated group (p<0.001), due to the presence of rutile crystalline structure. The total mass loss (Kwc), which includes mass loss due to wear (Kw) and that due to corrosion (Kc) were determined. The dominant wear regime was found for higher Ca/P groups (Kc/Kw≈0.05) and a mechanism of wear-corrosion for controls and lower Ca/P groups (Kc/Kw≈0.11). The group treated for 10min and enriched with Ag presented the lowest Kwc (p<0.05). Overall, MAO process was able to produce biofunctional oxide films with improved surface features, working as tribocorrosion resistant surfaces.608-2

Three-species Biofilm Model Onto Plasma-treated Titanium Implant Surface

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In this study, titanium (Ti) was modified with biofunctional and novel surface by micro-arc oxidation (MAO) and glow discharge plasma (GDP) and we tested the development of a three-species periodontopatogenic biofilm onto the treated commercially-pure titanium (cpTi) surfaces. Machined and sandblasted surfaces were used as control group. Several techniques for surface characterizations and monoculture on bone tissue cells were performed. A multispecies biofilm composed of Streptococcus sanguinis, Actinomyces naeslundii and Fusobacterium nucleatum was developed onto cpTi discs for 16.5 h (early biofilm) and 64.5 h (mature biofilm). The number of viable microorganisms and the composition of the extracellular matrix (proteins and carbohydrates) were determined. The biofilm organization was analyzed by scanning electron microscopy (SEM) and Confocal laser scanning microscopy (CLSM). In addition, MC3T3-E1 cells were cultured on the Ti surfaces and cell proliferation (MIT) and morphology (SEM) were assessed. MAO treatment produced oxide films rich in calcium and phosphorus with a volcano appearance while GDP treatment produced silicon-based smooth thin-film. Plasma treatments were able to increase the wettability of cpTi (p 0.05). Plasma treatment did not affect the viable microorganisms counts, but the counts of F. nucleaturn was lower for MAO treatment at early biofilm phase. Biofilm extracellular matrix was similar among the groups, excepted for GDP that presented the lowest protein content. Moreover, cell proliferation was not significantly affected by the experimental, except for MAO at 6 days that resulted in an increased cell proliferative. Together, these findings indicate that plasma treatments are a viable and promising technology to treat bone-integrated dental implants as the new surfaces displayed improved mechanical and biological properties with no increase in biofilm proliferation. (C) 2017 Elsevier B.V. All rights reserved.152354366State of Sao Paulo Research Foundation (FAPESP) [2013/26145-5, 2013/08451-1]Brazilian National Council for Scientific and Technological Development (CNPq) [442786/2014-0, 304908/2015-0]Fundo de Apoio ao Ensino, a Pesquisa e Extensao da UNICAMP (FAEPEX) [2032/15]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Functionalization of an experimental Ti-Nb-Zr-Ta alloy with a biomimetic coating produced by plasma electrolytic oxidation

This study developed an experimental quaternary titanium (Ti) alloy and evaluated its surface properties and electrochemical stability. The viability for a biofunctional surface treatment was also tested. Ti-35Nb-7Zr-5Ta (wt%) alloy was developed from pure metals. Commercially pure titanium (cpTi) and Ti-6Al-4V were used as controls. All groups had two surface conditions: untreated (machined surface) and modified by plasma electrolytic oxidation (PEO) (treated surface). The experimental alloy was successfully synthesized and exhibited β microstructure. PEO treatment created a porous surface with increased roughness, surface free energy, hardness and electrochemical stability (p < 0.05). For the machined surfaces, the Ti-Nb-Zr-Ta alloy presented the lowest hardness and elastic modulus (p < 0.05) and displayed greater polarization resistance relative to cpTi. Only PEO-treated cpTi and Ti-Al-V alloys exhibited anatase and rutile as crystalline structures. The β experimental Ti-Nb-Zr-Ta alloy seems to be a good alternative for the manufacture of dental implants, since it presents elastic modulus closer to that of bone, feasibility for surface treatment, electrochemical stability and absence of toxic elements77010381048FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2016/11470-6; 2017/01320-0This work was supported by the São Paulo State Research Foundation (FAPESP), Brazil (grant numbers 2016/11470-6 and 2017/01320-0). The authors express their gratitude to Jamille Altheman for her contribution and support at the Laboratory of Technological Plasmas at Univ. Estadual Paulista (UNESP), to Dr Richard Landers and Rita Vinhas from the University of Campinas (Institute of Physics Gleb Wataghin) for providing the XPS facility, to Dr Mathew T Mathew from the University of Illinois at Rockford (College of Medicine at Rockford, Department of Biomedical Sciences) for the donation of the electrochemical cell, and to the Brazilian Nanotechnology National Laboratory (LNNano) at the Brazilian Center of Research in Energy and Materials (CNPEM) for the XRD facilit

Incorporation of Ca, P, and Si on bioactive coatings produced by plasma electrolytic oxidation: The role of electrolyte concentration and treatment duration

The objectives of the present study were to produce bioactive coatings in solutions containing Ca, P, and Si by plasma electrolytic oxidation (PEO) on commercially pure titanium, to investigate the influence of different electrolytes concentration and treatment duration on the produced anodic films and to evaluate biocompatibility properties. The anodic films were characterized using scanning electron microscopy, energy-dispersive spectroscopy, atomic force microscopy, and x-ray diffraction and x-ray photoelectron spectroscopies. The surface energy and roughness were also evaluated. PEO process parameters influenced the crystalline structure formation and surface topography of the anodic films. Higher Ca content produced larger porous (volcanolike appearance) and thicker oxide layers when compared to the lower content. Treatment duration did not produce any topography difference. The treatment modified the surface chemistry, producing an enriched oxide layer with bioactive elements in the form of phosphate compounds, which may be responsible for mimicking bone surface. In addition, a rough surface with increased surface energy was generated. Optimal spreading and proliferation of human mesenchymal stem cells was achieved by PEO treatment, demonstrating excellent biocompatibility of the surface. The main finding is that the biofunctionalization with higher Ca/P on Ti-surface can improve surface features, potentially considered as a candidate for dental implants.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Effect Of Nonthermal Plasma Treatment On Surface Chemistry Of Commercially-pure Titanium And Shear Bond Strength To Autopolymerizing Acrylic Resin.

The effect of nonthermal plasma on the surface characteristics of commercially pure titanium (cp-Ti), and on the shear bond strength between an autopolymerizing acrylic resin and cp-Ti was investigated. A total of 96 discs of cp-Ti were distributed into four groups (n=24): Po (no surface treatment), SB (sandblasting), Po+NTP and SB+NTP (methane plasma). Surface characterization was performed through surface energy, surface roughness, scanning microscopy, energy dispersive spectroscopy, and X-ray diffraction tests. Shear bond strength test was conducted immediately and after thermocycling. Surface treatment affected the surface energy and roughness of cp-Ti discs (P<.001). SEM-EDS showed the presence of the carbide thin film. XRD spectra revealed no crystalline phase changes. The SB+NTP group showed the highest bond strength values (6.76±0.70MPa). Thermocycling reduced the bond strength of the acrylic resin/cp-Ti interface (P<.05), except for Po group. NTP is an effective treatment option for improving the shear bond strength between both materials.6037-4

Visible-light-induced photocatalytic and antibacterial activity of TiO2 codoped with nitrogen and bismuth: new perspectives to control implant-biofilm-related diseases

Biofilm-associated diseases are one of the main causes of implant failure. Currently, the development of process and focuses on the creation of surfaces with implant surface treatment goes beyond the osseointegration antimicrobial action and with the possibility to be re-activated (i.e., light source activation). Titanium dioxide (TiO2), an excellent photocatalyst used for photocatalytic antibacterial applications, could be a great alternative, but its efficiency is limited to the ultraviolet (UV) range of the electromagnetic spectrum. Since UV radiation has carcinogenic potential, we created a functional TiO2 coating codoped with nitrogen and bismuth via the plasma electrolytic oxidation (PEO) of titanium to achieve an antibacterial effect under visible light with re-activation potential. A complex surface topography was demonstrated by scanning electron microscopy and three-dimensional confocal laser scanning microscopy. Additionally, PEO-treated surfaces showed greater hydrophilicity and albumin adsorption compared to control, untreated titanium. Bismuth incorporation shifted the band gap of TiO2 to the visible region and facilitated higher degradation of methyl orange (MO) in the dark, with a greater reduction in the concentration of MO after visible-light irradiation even after 72 h of aging. These results were consistent with the in vitro antibacterial effect, where samples with nitrogen and bismuth in their composition showed the greatest bacterial reduction after 24 h of dual-species biofilm formation (Streptococcus sanguinis and Actinomyces naeslundii) in darkness with a superior effect at 30 min of visible-light irradiation. In addition, such a coating presents reusable photocatalytic potential and good biocompatibility by presenting a noncytotoxicity effect on human gingival fibroblast cells. Therefore, nitrogen and bismuth incorporation into TiO2 via PEO can be considered a promising alternative for dental implant application with antibacterial properties in darkness, with a stronger effect after visible-light application11201818618202COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação2017/00314-6; 2017/01320-0; 2016/11470-6This study was financed by the State of Sao Paulo Research Foundation (FAPESP) (grant numbers 2017/00314-6, 2017/01320-0 and 2016/11470-6) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001. We thank the Oral Biochemistry Lab at Piracicaba Dental School, University of Campinas, for providing their microbiology facility and the Brazilian Nanotechnology National Laboratory (LNNano) at the Brazilian Center of Research in Energy and Materials (CNPEM) for the CLSM, XPS, and XRD facilities. We also thank Professor Dr Ricardo Armini Caldas for his contribution to the elaboration of a table of contents graphic desig