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Abstract: The effects of surface modifications and bacteria on the corrosion behavior of titanium have been studied. Five surface modifications were analyzed: two acid etchings (op V, op N), acid etching + anodic oxidation (op NT), sandblasting + acid etching (SLA), and machined surfaces (mach). The corrosion behavior of the surface modifications was evaluated by following the standard ANSI/AAMI/ISO 10993‐15:2000. Cyclic potentiodynamic and potentiostatic anodic polarization tests and ion release by ICP‐OES after immersion for 7 days in 0.9% NaCl were carried out. Microbiologically induced corrosion (MIC) of low and high roughness (mach, op V) was assessed in situ by electrochemical techniques. Streptococcus mutans bacteria were resuspended in PBS at a concentration of 3 × 108 bacteria mL−1 and maintained at 37°C. MIC was measured through the open circuit potential, Eoc, and electrochemical impedance spectroscopy from 2 to 28 days. Potentiodynamic curves showed the typical passive behavior for all the surface modifications. The titanium ion release after immersion was below 3 ppb. In situ bacteria monitoring showed the decrease in Eoc from −0.065 (SD 0.067) Vvs. Ag/AgCl in mach and −0.115 (SD 0.084) Vvs. Ag/AgCl in op V, to −0.333 (SD 0.147) Vvs. Ag/AgCl in mach and −0.263 (SD 0.005) Vvs. Ag/AgCl in op V, after 2 and 28 days, respectively. A reduction of the oxide film resistance, especially in op V (54 MΩ cm2 and 6 MΩ cm2, after 2 and 28 days, respectively) could be seen. Streptococcus mutans negatively affected the corrosion resistance of titanium. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 997–1009, 2018. [ABSTRACT FROM AUTHOR]

In the biomedical field, water contact angle is a useful gauge to follow how a biomaterial surface would interact with the surrounding water-like physiological environment. Ti6Al4V alloy is widely used in orthopedic applications. Nevertheless, the values of its water contact angle reported in the literature show a large dispersion, from 40° up 80°. However, in addition to the expected dependence of the surface wettability on preliminary treatments, the values of the water contact angle on the pristine Ti6Al4V alloy suffers from an important variability and lack of reproducibility. The present research pays attention to this difficulty and proposes a simple experimental procedure to ensure adequate contact angle reproducibility. Controlled passivation growth in mild underwater conditions of freshly polished disks, followed by ultrasonic washing, avoiding the rubbing of the surface, gives average water contact angles of 80° with very low standard deviations also among samples from the same batch. [ABSTRACT FROM AUTHOR]

The effects of surface modifications and bacteria on the corrosion behavior of titanium have been studied. Five surface modifications were analyzed: two acid etchings (op V, op N), acid etching + anodic oxidation (op NT), sandblasting + acid etching (SLA), and machined surfaces (mach). The corrosion behavior of the surface modifications was evaluated by following the standard ANSI/AAMI/ISO 10993-15:2000. Cyclic potentiodynamic and potentiostatic anodic polarization tests and ion release by ICP-OES after immersion for 7 days in 0.9% NaCl were carried out. Microbiologically induced corrosion (MIC) of low and high roughness (mach, op V) was assessed in situ by electrochemical techniques. Streptococcus mutans bacteria were resuspended in PBS at a concentration of 3 × 10 8 bacteria mL -1 and maintained at 37°C. MIC was measured through the open circuit potential, E oc , and electrochemical impedance spectroscopy from 2 to 28 days. Potentiodynamic curves showed the typical passive behavior for all the surface modifications. The titanium ion release after immersion was below 3 ppb. In situ bacteria monitoring showed the decrease in E oc from -0.065 (SD 0.067) V vs. Ag/AgCl in mach and -0.115 (SD 0.084) V vs. Ag/AgCl in op V, to -0.333 (SD 0.147) V vs. Ag/AgCl in mach and -0.263 (SD 0.005) V vs. Ag/AgCl in op V, after 2 and 28 days, respectively. A reduction of the oxide film resistance, especially in op V (54 MΩ cm 2 and 6 MΩ cm 2 , after 2 and 28 days, respectively) could be seen. Streptococcus mutans negatively affected the corrosion resistance of titanium. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 997-1009, 2018., (© 2017 Wiley Periodicals, Inc.)