1. Influence of the oxidizing technique on the biocompatible and corrosion properties of Ti6Al4V in a physiological environmentMirjam Bajt Leban, Tadeja Kosec, Aleksandra Kocijan, Marjetka Conradi, Ita Junkar, Janez Kovač, 2025, izvirni znanstveni članek Povzetek: This work aims to evaluate the corrosion and biocompatibility properties of oxide films generated on Ti6Al4V alloys using both traditional and novel methods. Oxide films were generated by anodization and plasma treatment to achieve a blue surface finish. The oxide films were then characterized and compared to a native film formed on the Ti6Al4V.
Electrochemical tests, incorporating potentiodynamic tests and electrochemical impedance spectroscopy, were employed to define the electrochemical resistance of oxides in an environment simulating biological exposure. In vitro tests were conducted to study ion release and biocompatible properties over a 6-week period of exposure to a 0.9 wt% NaCl solution, at body temperature. Various spectroscopic techniques, including ToF-SIMS, XRD, and Raman analysis, were used to study the structure and chemistry of the oxide films. The sub-surface layer was analysed by microstructural investigation.
The type of oxidation was found to have a key influence on the oxide composition, especially with respect to the depth distribution of the individual alloy elements through the oxide film. The oxidation process determines which of the alloying elements are released into the environment, as a result of the corrosion reactions.
Ključne besede: oxide film, biocompatibility, surface characterization, ion release, simulated body fluid
Objavljeno v DiRROS: 16.10.2024; Ogledov: 1364; Prenosov: 885
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2. A critical appraisal of the use and properties of nickel–titanium dental alloysPetra Močnik, Tadeja Kosec, 2021, pregledni znanstveni članek Povzetek: Nickel–titanium (NiTi) archwires are used in dentistry for orthodontic treatment. NiTi alloys have favourable mechanical characteristics, such as superelasticity and shape memory, and are also known as a corrosion-resistant alloy. In specific cases, an archwire could be attacked by certain types of corrosion or wear degradation, which can cause the leaching of metal ions and a hypersensitive response due to increased concentrations of Ni in the human body. A systematic search of the literature retrieved 102 relevant studies. The review paper focuses on three main fields: (i) electrochemical properties of NiTi wires and the effect of different environments on the properties of NiTi wires (fluoride and low pH); (ii) tribocorrosion, a combination of chemical and mechanical wear of the material, and (iii) the biocompatibility of NiTi alloy and its subsequent effect on the human body. The review showed that corrosion properties are affected by microstructure, pH of saliva and the presence of fluorides. A high variation in published results should be, therefore, interpreted with care. The release of nickel ions was assessed using the same unit, showing that the vast majority of metal ions were released in the first few days of exposure, then a stable, steady state was reached. In tribocorrosion studies, the increased concentrations of Ni ions were reported.
Ključne besede: NiTi alloy, archwires, corrosion, NI ion release
Objavljeno v DiRROS: 23.02.2024; Ogledov: 1534; Prenosov: 823
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3. Corrosion characterization and ion release in SLM-manufactured and wrought Ti6Al4V alloy in an oral environmentMirjam Bajt Leban, Tadeja Kosec, Matjaž Finšgar, 2022, izvirni znanstveni članek Povzetek: As-produced and heat-treated TiAlV samples were prepared by selective laser melting and compared to wrought samples of identical chemical composition. Microstructural, corrosion, and spectroscopic studies of additively manufactured samples in artificial saliva at 37 °C, with NaF and at pH 2.3 were as a novelty combined with metal ion release during 42 days immersion. In artificial saliva higher amount of ions was released on SLM specimen when compared to wrought alloy. The total amount of ions released from SLM specimen in AS containing NaF was 10-times higher than in AS, while in AS with lactic acid it was 100-times higher.
Ključne besede: Ti6Al4V, SLM, corrosion, ion release, XPS, ToF-SIMS
Objavljeno v DiRROS: 31.05.2023; Ogledov: 1425; Prenosov: 1479
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4. Differences between 3-D printed and traditionally milled CoCr dental alloy from casted block in oral environmentMirjam Bajt Leban, Matej Kurnik, Igor Kopač, Matic Klug Jovičević, Bojan Podgornik, Tadeja Kosec, 2023, izvirni znanstveni članek Povzetek: The aim of this study was to compare corrosion resistance and ion release in CoCr dental alloys with identical chemical compositions produced using different technologies (SLM – selective laser melting and milling from cast blocks) and heat treatment (SLM parts only). The corrosion properties were tested in artificial saliva, artificial saliva with fluoride ions, and artificial saliva with added lactic acid to simulate inflammations. The study included electrochemical tests, microstructural investigation and ion release tests in the three different environments for a total of 42 days. The best performance of CoCr as a result of potentiodynamic polarization was observed in the artificial saliva with added lactic acid, which is in contradiction with the highest ion release measured from all the materials tested and electrochemical impedance spectroscopy that showed a deterioration of the passive layer in an acidic environment. Microstructural investigation revealed that different phases precipitated by heat treatment trigger increased release of Mo and W ions. The printing method does not raise critically ion release from CoCr alloy, while the state of the surface greatly impacts the extent of the ion release. This study demonstrates the importance of an interdisciplinary approach to the study of corrosion and biocompatibility in dental alloys.
Ključne besede: CoCr dental alloy, selective laser melting, corrosion, ion release, artificial saliva
Objavljeno v DiRROS: 29.05.2023; Ogledov: 1570; Prenosov: 1377
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