Tribo-electrochemical behavior of bio-functionalized TiO2 nanotubes in artificial saliva: Understanding of degradation mechanisms

Abstract

It has been shown that the synthesis of TiO 2 nanotubes by anodization provides outstanding properties to Ti surfaces intended for dental and orthopedic implants applications. Beyond the very well-known potential of these surfaces to improve osseointegration and avoid infection, the knowledge on the adhesion and degradation behavior of TiO 2 nanotubes under the simultaneous action of wear and corrosion is still poorly understood and these are issues of tremendous importance. The main aim of this work is to investigate, for the first time, the tribo-electrochemical degradation behavior of Ti surfaces decorated with TiO 2 nanotubes before and after biofunctionalization treatments. Well-aligned TiO 2 nanotubes (NTs) were produced containing elements natively present in bone such as calcium (Ca) and phosphorous (P), in addition of zinc (Zn) as an antimicrobial agent and stimulator of bone formation. The synthesis of Ca/P/Zn-doped nanotubes (NT-Ca/P/Zn) was achieved by reverse polarization and anodization treatments applied to conventional TiO 2 nanotubes grown by two-step anodization. The nanotube surfaces were analyzed by scanning electron microscopy (SEM) while dark-field scanning transmission electron microscopy (STEM-DF) was used to characterize the Ti/TiO 2 nanotubular films interfaces. Tribo-electrochemical tests were conducted under reciprocating sliding conditions in artificial saliva. The open circuit potential (OCP) was monitored before, during and after sliding tests, and the coefficient of friction (COF) values were registered during rubbing action. The wear tracks resulting from sliding tests were characterized by SEM and wear volume measurements were carried out by 2D profilometry. The results show that the tribo-electrochemical behavior of TiO 2 nanotubes was significantly improved after bio-functionalization treatments. The higher electrochemical stability and lower mechanical degradation of these films was correlated with their improved adhesion strength to Ti substrate, which is granted by the nanothick oxide film formed at the interface region, during bio-functionalization processes. A first insight on the degradation mechanisms taking place during tribo-electrochemical action is proposed. The outcomes of this study may contribute in a great extent for the development of new implant surfaces with improved biomechanical stability and thus contribute for the long term success of dental implants.

Progression of Bio-Tribocorrosion in Implant Dentistry

“…After screening full texts, a total of 44 studies were included considering the tribocorrosion analyses for dental implants and frameworks applications. The characteristics of the 44 studies (Vieira et al, 2006;Banu et al, 2008;Richard et al, 2010;Souza et al, 2010aSouza et al, , 2012Sivakumar et al, 2011;Dimah et al, 2012;Mardare et al, 2012;Mathew et al, 2012a,b;Albayrak et al, 2013;Alves et al, 2013Alves et al, , 2014Alves et al, , 2017Alves et al, , 2018Benea et al, 2013Benea et al, , 2015Benea et al, , 2017Licausi et al, 2013a,b;Fazel et al, 2015;Figueiredo-Pina et al, 2015;Golvano et al, 2015;Oliveira et al, 2015;Buciumeanu et al, 2016Buciumeanu et al, , 2017Correa et al, 2016;Guinon Pina et al, 2016;Marques et al, 2016;Mindivan et al, 2016;Pontes et al, 2016;Sampaio et al, 2016b;Silva et al, 2016;Bryant and Neville, 2017;Danaila and Benea, 2017;Mindivan and Mindivan, 2018;Sikora et al, 2018;Trino et al, 2018;Wang et al, 2018;Branco et al, 2019;Corne et al, 2019;Cui et al, 2019a,b;…”

“…The human body represents a challenging condition for any biomaterial due to mechanical, chemical, biochemical, and microbiological degradation processes (Apaza-Bedoya et al, 2017). In this context, bio-tribocorrosion studies can enable understanding the irreversible degradation mechanisms that biomedical devices are exposed by analyzing the synergistic effect of wear and corrosion Alves et al, 2017). Hence, the bio-tribocorrosion provides valuable information on mechanisms that influence the performance of implants in biological systems (Mathew et al, 2011).…”

Advanced Surface Treatments on Titanium and Titanium Alloys Focused on Electrochemical and Physical Technologies for Biomedical Applications

“…Therefore, tribocorrosion studies become of fundamental importance, not only because of the high probability of adhesion failure of the nanotubular systems, but also because of their high clinical relevance, since implant degradation in vivo can seriously compromise osseointegration or even its long-term stability. In the attempt to construct effective nanotubular systems based on an integrated and multidisciplinary approach that addresses the development of tribocorrosion resistant implant surfaces with potential to avoid infection, and simultaneously, promote osseointegration, Alves and co-workers have recently reported, for the first time, important findings on the tribocorrosion field [101,102].…”

“…Alves et al [101] studied the tribo-electrochemical behavior of bio-functionalized TiO 2 NTs in AS, providing a first insight on their degradation mechanisms under reciprocating sliding conditions. Titanium surfaces decorated with TiO 2 NTs of 50-90 nm diameter were bio-functionalized by anodizing in an electrolyte containing Ca, P and Zn.…”

Preliminary investigation on the tribocorrosion behaviour of nanotubular structured Ti6Al4V surfaces

“…However, knowledge on the tribocorrosion behaviour of these surfaces are scarce. A recent study on the tribocorrosion behaviour of NT arrays formed on commercially-pure Ti surfaces showed that cracking and detaching of the NT arrays is critical for the tribocorrosion performance of these surfaces [10]. However, the tribocorrosion behaviour of NT arrays formed on Ti alloys is yet to be evaluated.…”