Determinants of corrosion resistance of Ti-6Al-4V alloy dental implants in an In Vitro model of peri-implant inflammation

• Published in: PloS one 2019-01, Vol.14 (1), p.e0210530-e0210530
• Main Authors: Berbel, Larissa O, Banczek, Everson do P, Karoussis, Ioannis K, Kotsakis, Georgios A, Costa, Isolda
• Format: Article
• Language: English
• Subjects: Acid resistance; Acids - chemistry; Adsorption; Albumin; Alloys; Anodic polarization; Backup software; Biocompatibility; Biofilms; Biology and Life Sciences; Biomedical materials; Chemical properties; Computational fluid dynamics; Computer simulation; Corrosion; Corrosion (Chemistry); Corrosion effects; Corrosion products; Corrosion resistance; Corrosion resistant alloys; Corrosion resistant materials; Deaeration; Dental alloys; Dental Alloys - chemistry; Dental implants; Dental Implants - standards; Dental prosthetics; Dental restorative materials; Electrochemical impedance spectroscopy; Electrochemical Techniques - methods; Electrochemistry; Electrode polarization; Engineering and Technology; Health aspects; Humans; Hydrogen; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydrogen-Ion Concentration; Inflammation; Inflammation - chemically induced; Inflammation - complications; Materials Testing - methods; Medicine and Health Sciences; Metals (Materials); Microscopy, Electron, Scanning; Models, Chemical; Open circuit voltage; Oral cavity; Oxidation; Oxide coatings; Oxygen; Peroxides; Physical Sciences; Physiology; Proteins; Reactive oxygen species; Risk factors; Specialty metals industry; Spectroscopy; Steel corrosion; Surface Properties; Surgical implants; Titanium; Titanium - chemistry; Titanium alloys; Titanium base alloys; Titanium dioxide
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0210530

Titanium (Ti) and its alloys possess high biocompatibility and corrosion resistance due to Ti ability to form a passive oxide film, i.e. TiO2, immediately after contact with oxygen. This passive layer is considered stable during function in the oral cavity, however, emerging information associate inflammatory peri-implantitis to vast increases in Ti corrosion products around diseased implants as compared to healthy ones. Thus, it is imperative to identify which factors in the peri-implant micro-environment may reduce Ti corrosion resistance. The aim of this work is to simulate peri-implant inflammatory conditions in vitro to determine which factors affect corrosion susceptibility of Ti-6Al-4V dental implants. The effects of hydrogen peroxide (surrogate for reactive oxygen species, ROS, found during inflammation), albumin (a protein typical of physiological fluids), deaeration (to simulate reduced pO2 conditions during inflammation), in an acidic environment (pH 3), which is typical of inflammation condition, were investigated. Corrosion resistance of Ti-6Al-4V clinically-relevant acid etched surfaces was investigated by electrochemical techniques: Open Circuit Potential; Electrochemical Impedance Spectroscopy; and Anodic Polarization. Electrochemical tests confirmed that most aggressive conditions to the Ti-6Al-4V alloy were those typical of occluded cells, i.e. oxidizing conditions (H2O2), in the presence of protein and deaeration of the physiological medium. Our results provide evidence that titanium's corrosion resistance can be reduced by intense inflammatory conditions. This observation indicates that the micro-environment to which the implant is exposed during peri-implant inflammation is highly aggressive and may lead to TiO2 passive layer attack. Further investigation of the effect of these aggressive conditions on titanium dissolution is warranted.