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Ogawa E.S.,University of Campinas | Ogawa E.S.,IBTN Br Institute of Biomaterials | Matos A.O.,University of Campinas | Matos A.O.,IBTN Br Institute of Biomaterials | And 15 more authors.
Materials Science and Engineering C | Year: 2016

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 (S); 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 (Rp) and the lowest capacitance (Q) and corrosion current density (Icorr) values. Reduced corrosion stability was noted for the sandblasted groups. Acidic artificial saliva decreased the Rp values of cp-Ti surfaces and produced the highest Icorr 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. © 2016 Elsevier B.V. All rights reserved. Source

Marques I.D.S.V.,University of Campinas | Marques I.D.S.V.,IBTN Institute of Biomaterials | Marques I.D.S.V.,IBTN Br Institute of Biomaterials | Alfaro M.F.,IBTN Institute of Biomaterials | And 9 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2016

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 (0.3 M/0.02 M or 0.1 M/0.03 M) incorporated with/without Ag (0.62 g/L) or Si (0.04 M); and treatment duration (5 and 10 min). 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 10 min 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. © 2015 Elsevier Ltd. Source

Beline T.,University of Campinas | Beline T.,IBTN Br Institute of Biomaterials | Garcia C.S.,University of Campinas | Ogawa E.S.,University of Campinas | And 12 more authors.
Materials Science and Engineering C | Year: 2016

The role of surface treatment on the electrochemical behavior of commercially pure titanium (cpTi) exposed to mouthwashes was tested. Seventy-five disks were divided into 15 groups according to surface treatment (machined, sandblasted with Al2O3, and acid etched) and electrolyte solution (artificial saliva - control, 0.12% chlorhexidine digluconate, 0.05% cetylpyridinium chloride, 0.2% sodium fluoride, and 1.5% hydrogen peroxide) (n = 5). Open-circuit-potential and electrochemical impedance spectroscopy were conducted at baseline and after 7 and 14 days of immersion in each solution. Potentiodynamic test and total weight loss of disks were performed after 14 days of immersion. Scanning electron microscopy, energy dispersive spectroscopy, white light interferometry and profilometry were conducted for surface characterization before and after the electrochemical tests. Sandblasting promoted the lowest polarization resistance (Rp) (P < .0001) and the highest capacitance (CPE) (P < .006), corrosion current density (Icorr) and corrosion rate (P < .0001). In contrast, acid etching increased Rp and reduced CPE, independent to the mouthwash; while hydrogen peroxide reduced Rp (P b .008) and increased Icorr and corrosion rate (P < .0001). The highest CPE values were found for hydrogen peroxide and 0.2% sodium fluoride. Immersion for longer period improved the electrochemical stability of cpTi (P < .05). In conclusion, acid etching enhanced the electrochemical stability of cpTi. Hydrogen peroxide and sodium fluoride reduced the resistance to corrosion of cpTi, independent to the surface treatment. Chlorhexidine gluconate and cetylpyridinium chloride did not alter the corrosive behavior of cpTi. © 2015 Elsevier B.V. All rights reserved. Source

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