Understanding growth mechanisms and tribocorrosion behaviour of porous TiO2 anodic films containing calcium, phosphorous and magnesium

Abstract

The growth of the dental implant market increases the concern regarding the quality, efficiency, and lifetime of dental implants. Titanium and its alloys are dominant materials in this field thanks to their high biocompatibility and corrosion resistance, but they possess a very low wear resistance. Besides problems related to osteointegration and bacterial infections, tribocorrosion phenomena being the simultaneous action between corrosion and wear, are likely to occur during the lifetime of the implant. Therefore, tribocorrosion resistant surfaces are needed to guarantee the preservation of dental implants. This work focused on the incorporation of magnesium, together with calcium and phosphorous, in the structure of titanium oxide films produced by micro-arc oxidation (MAO). The characterization of morphology, chemical composition, and crystalline structure of the surfaces provided important insights leading to 1) a better understanding of the oxide film growth mechanisms during the MAO treatment; and 2) a better awareness on the degradation process during tribocorrosion tests. The addition of magnesium was shown to support the formation of rutile which improves the tribocorrosion properties of the surfaces.

Tribocorrosion Behavior of Calcium- and Phosphorous-Enriched Titanium Oxide Films and Study of Osteoblast Interactions for Dental Implants

“…The corrosion and tribocorrosion behaviors of the anodic films synthesized in the Cβ electrolyte were undoubtedly better than for cp-Ti_Reference and PEOtreated samples in CE electrolyte. The same trend was observed by Oliveira et al [63] after tribocorrosion studies carried out in PEO-treated samples. They observed that the electrochemical behavior of all PEO-treated samples was improved as compared to cp-Ti group, from the point of view of both corrosion and tribocorrosion.…”

“…x behavior was also reported by Oliveira et al [63]. All PEOtreated samples in CE electrolyte displayed lower OCP values and so, higher corrosion tendency, when compared to samples treated in the Cβ electrolyte.…”

“…3a), revealing an increase on corrosion tendency. This indicates the fast After sliding, the OCP increased straight away to more noble values due to a re-growth of the passive film (repassivation) in the wear track [18,30,63]; however, it did not come back to the level before reciprocating sliding. This might indicate that the electrochemical state of the cpTi surface has been modified by the wear induced during mechanical solicitation, and therefore the newly formed passive film has dissimilar features when compared with the naturally one formed before mechanical loading [2].…”

“…The authors hypothesized that the reason for the much better tribocorrosion behavior of samples anodized in the higher calcium acetate concentration electrolyte, was the crystalline structure (presence of anatase/rutile) and calcium content on those samples. More recently, Oliveira et al [58] produced and investigated the tribocorrosion behavior of porous TiO 2 anodic films containing calcium, phosphorous, and magnesium. They concluded that micro-arc oxidation treatments induced the formation of a nanocomposite gradient crystalline structure and that the addition of magnesium to the anodizing electrolyte increased the percentage of crystalline rutile, which are thought to be determining factors for achieving an improved tribocorrosion behavior of the surfaces.…”

“…This electrolyte was chosen once on one side, it has been generally used in previous research works [2,18,61,62,63] but also because the electrochemical behavior of metallic materials in Fusayama's saliva, its similar to the one observed in human saliva [64]. It is aimed to simulate the highly corrosive oral cavity environment with Cl − , F − , and H + ions playing a significant role on corrosion of dental implant materials [20].…”