Biofunctional properties and electrochemical behavior of loose sintering titanium alloys under simulated oral conditions and acidic dietary habits

This study investigates the effect of copper (Cu) and silver (Ag) additions on the electrochemical behavior of the Fe40Al intermetallic alloy in artificial saliva, aiming to evaluate its potential for biomedical applications such as dental implants. Alloys with varying concentrations of Ag (0.5, 1.0, and 3.0 wt%) and Cu (1.0, 3.0, and 5.0 wt%) were synthesized and exposed to a biomimetic electrolyte simulating oral conditions. Electrochemical techniques, including open circuit potential (OCP), linear polarization resistance (LPR), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS), were employed to assess corrosion performance. Results show that unmodified Fe40Al exhibits good corrosion resistance, attributed to the formation of a stable passive oxide layer. The addition of Cu, particularly at 3.0 wt%, significantly improved corrosion resistance, yielding lower corrosion current densities and higher polarization resistance and charge transfer resistance values, surpassing even 316L stainless steel in some metrics. Conversely, Ag additions led to a degradation of corrosion resistance, especially at 3.0 wt%, due to microstructural changes and the formation of metallic Ag precipitates, AgSCN, and galvanic cells, which promoted localized corrosion. EIS results revealed that Cu- and Ag-modified alloys developed less homogeneous and less protective passive layers over time, as indicated by increased double-layer capacitance (Cdl) and reduced constant phase element exponent (ndl) values. Overall, the Fe40Al alloy shows intrinsic corrosion resistance in simulated physiological environments, and Cu additions can enhance this performance under controlled conditions. However, Ag additions negatively affect the protective behavior of the passive layer. These findings offer critical insight into the design of Fe-Al-based biomaterials for dental or biomedical applications where corrosion resistance and electrochemical stability are paramount.

Background/Objectives: The purpose of this study was to assess the in vitro biocompatibility and corrosion resistance of five titanium alloys that have been recently developed for dental implant applications, whose compositions were designed to align with current approaches in the development of novel biomaterials. Priority was given to limiting the harmfulness associated with specific chemical elements present in common conventional alloys and increasing corrosion resistance to improve the biomaterial–tissue cellular interaction. Methods: For this purpose, five types of titanium alloys with original chemical compositions (Ti1–Ti5) were developed. The electrochemical behavior of the alloys was analyzed by evaluating the corrosion resistance in environments that simulate the oral environment, as well as the cellular behavior, by evaluating the viability, growth, and proliferation of human cells on osteoblasts and gingival fibroblasts. Detailed analysis of the chemical composition by scanning electron microscope (SEM/EDS) methods was used. The corrosion rate of the alloys in artificial saliva was tested using the polarization resistance technique (Tafel). Human osteoblasts (hFOB cell line) and human gingival fibroblasts (hFIB-G cell line) were used to measure biocompatibility in vitro. Results: The Ti5 alloy demonstrated the highest cell viability and the lowest corrosion rate (0.114 μm/year) among all tested compositions, with the Ti3 alloy containing Mo and Zr following closely behind. The Ti2 alloy exhibited reduced biocompatibility because of the inclusion of Ni and Fe in its composition. Conclusions: Taken together, the results of this study provide useful information on the basic characteristics of titanium alloys with original chemical compositions. The titanium alloys were analyzed in comparison with common conventional alloys (Cp–Ti and Ti6Al4V) as well as alloys such as Ti–Zr, Ti–Nb, and Ti–Nb–Zr–Ta, which are considered to be viable alternatives to conventional materials for making dental implants.

Titanium alloys are widely used in dental implants due to their superior biocompatibility and mechanical strength. However, these alloys are prone to corrosion and wear in the oral environment, thereby shortening their clinical lifespan. This study investigates the enhancement of titanium alloy surface properties using magnetic abrasive finishing (MAF) and examines the influence of magnetic needle diameters (0.2–1.5 mm) on surface modification. Titanium alloy samples were processed by MAF and systematically evaluated for surface morphology, grain size, surface hardness, residual stress, electrochemical corrosion behavior, and tribological performance. Results demonstrated that MAF improves surface morphology, significantly refines grain size, and enhances surface hardness and compressive residual stress, thereby optimizing surface properties. The 1.0 mm magnetic needle group demonstrated the best performance, achieving a Vickers hardness of 376.71 ± 12.48 HV and a compressive residual stress of −579.1 ± 8.49 MPa. In addition, this group showed a higher self-corrosion potential (−0.5661 V), a lower corrosion current density (0.0114 μA·cm−2), and the lowest wear rate ((4.49 ± 0.42) × 10−4 mm3/N·m) in artificial saliva, demonstrating superior corrosion and wear resistance. Overall, MAF technology markedly enhances the surface integrity of titanium alloys in artificial saliva through the synergistic effects of grain refinement and stress modulation. These findings provide valuable experimental evidence supporting future efforts to optimize the surface properties of titanium alloy dental implants.

Influence of the fabrication process and fluoride content on the tribocorrosion behaviour of Ti6Al4V biomedical alloy in artificial saliva

Effect of Ag on the corrosion behavior of Ti–Ag alloys in artificial saliva solutions

Based on their high mechanical strength, Ti-based high-entropy alloys (HEAs) are of great potential as materials for high-performance reduced-diameter dental implants. Despite previous studies demonstrating their corrosion resistance in various simulated body fluids, their resistance in simulated buccal conditions has yet to be confirmed. In this work, the corrosion behavior of two Ti-based HEAs, TiZrHfNb, and TiZrHfNbTa was evaluated in comparison to CP-Ti and Ti-6Al-4V in artificial saliva (AS) solution and in AS with fluoride ion content (ASF). A set of electrochemical tests (electrochemical impedance spectroscopy, cyclic polarization, and Mott-Schottky) was employed and complemented with surface characterization analyses (scanning electron microscopy and atomic force microscopy) to determine dissolution and passivation mechanisms of the alloys. In general, the HEAs exhibited a far superior corrosion resistance compared to CP-Ti and Ti-6Al-4V alloys in both solutions. In the AS solution, the TiZrHfNb exhibited the highest polarization resistance and pitting potential, indicating a high corrosion resistance due to the formation of a robust passive layer. Whilst in the ASF solution, the TiZrHfNbTa showed a greater corrosion resistance due to the synergistic effect of Nb and Ta oxides that enhanced passive film stability. This finding emphasizes the role of Ta in elevating the corrosion resistance of Ti-based HEAs in the presence of fluoride ions and confirms the importance of chemical composition optimization in the development of next-generation dental alloys. Based on its electrochemical corrosion behavior, TiZrHfNbTa HEAs are promising new materials for high-performance reduced-diameter dental implants.

Electrochemical impedance spectroscopy study of Ti–6Al–4V alloy in artificial saliva with fluoride and/or bovine albumin

Titanium and its alloys has been widely used for the design of dental implants because of its biocompatibility, mechanical properties and corrosion resistance. The powder-metallurgy process is a promising alternative to the casting fabrication process of titanium alloys for bone implants design as the porous structure mimics the natural bone structures, allowing the bone to grow into the pores which results in a better fixation of the artificial implant. However, under in vivo conditions the implants are subjected to tribocorrosion phenomenon, which consists in the degradation mechanisms due to the combined effect of wear and corrosion. The aim of this study is to evaluate the tribocorrosion behaviour of cast and sintered Ti6Al4V biomedical alloy for dental applications using the cast material as reference. Titanium samples were tested in artificial human saliva solution with three different pHs (3, 6, 9) and in an acidic saliva with 1000 ppm fluorides (AS-3-1000F−) by different electrochemical techniques (potentiodynamic curves, potentiostatic tests and tribo-electrochemical tests). Cast and sintered titanium alloys exhibit the same tribocorrosion mechanisms in AS independently of the pH which consists in plastic deformation with passive dissolution, but the addition of fluorides to the acidified solution changes the degradation mechanism towards active dissolution of the titanium alloys.

Titanium is the most common material chosen for dental implants because it is highly corrosion resistant because it constantly reforms a protective passive film layer. The formation and composition of the passive film layer is dependent on the environmental conditions. If the stable oxide layer is damaged, the titanium surface underneath can corrode. The purpose of this study was to determine if basic corrosion of commercially pure titanium (CpTi) alloy in artificial saliva was affected by pH and to understand the corrosion kinetics/mechanisms of CpTi as a function of pH. In this study, titanium alloy discs were subjected to corrosion tests. Before the tests, all samples were cleaned and polished using standard metallographic preparation methods. Artificial saliva was used as the testing medium. The following pH values were tested: 3.0, 4.5, 6.0, 6.5, 7.5, and 9.0. Different pH values were achieved by adding lactic acid (acidic) or NaOH (basic) in appropriate amounts. Potentiodynamic curves indicated behavior change at each pH. In addition, the corrosion current density value determined from the potentiodynamic curve exhibited the poorest corrosion resistance for pH 7.5. The Nyquist plot (from the electrochemical impedance spectroscopy results) indicated that pH 7.5 had the poorest resistance. Scanning electron microscopy images indicated that pH levels of 6.5, 7.5, and 9.0 had considerable surface corrosion. The results showed that the media's pH significantly influenced the corrosion behavior of CpTi. The poor corrosion behavior at the neutral pHs invites some concerns and highlights the need for further study.

Electrochemical behavior of Ti–Cr alloys in artificial saliva

Copper barrel brandy can be taken orally with dilution of bisleri water or soda water and without dilution. People clipped with orthodontic wires may take copper barrel brandy orally, with dilution of without dilution. How far the orthodontic wires will be affected by these items? To find an answer the present research work is undertaken. Corrosion resistance of orthodontic wires made of Ni-Ti alloy and Ni-Cr alloy in artificial saliva in the absence and presence of copper barrel, water and soda water has been evaluated by AC impedance spectra. It is generally observed that Ni-Ti alloy is more corrosion resistant than Ni-Cr alloy in artificial saliva in the presence of copper barrel, water and soda water. When orthodontic wire made of Ni-Ti is immersed in artificial saliva, the charge transfer resistance (Rt) value is 31945Ohmcm2 . When it is immersed in copper barrel + artificial saliva (AS) system, Rtvalue increase to 80000Ohmcm2 . When it is immersed in soda water + artificial saliva (AS) system, Rtvalue increase to 76450Ohmcm2 . When it is immersed in water + artificial saliva (AS) system, Rtvalue increase to 82620Ohmcm2 . On the other hand, when orthodontic wire made of Ni-Cr is immersed in artificial saliva, the charge transfer resistance (Rt) value is 80930Ohmcm2 . When it is immersed in copper barrel + artificial saliva (AS) system, Rtvalue decrease to 11104Ohmcm2 . When it is immersed in soda water + artificial saliva (AS) system, Rtvalue decrease to 10437Ohmcm2 . It implies that the people who have been clipped with orthodontic wire made of Ni-Ti alloy can take copper barrel in any form, namely, with dilution or without dilution. The people who have been clipped with orthodontic wire made of Ni-Cr alloy should avoid taking copper barrel in any form, namely, with dilution or without dilution.

Electrochemical behaviour of titanium and dental alloys in artificial saliva

Electrochemical corrosion study of CH-xTiO2 (x=Ag, Mg, Sr, and Zn) coated Ti–6Al–4V alloy for dental implant

Dental implants are exposed to a wide range of pH values of saliva and different concentrations of fluoride. In order to prevent plaque and caries formation, prophylactic products have been used more commonly for dental treatments. These products contain different concentrations of fluoride, for example; bucal rinses, toothpastes and gels contain 200ppm, 1000-1500 ppm and 10000-20000 ppm of fluoride respectively with the pH varying from acidic values to neutral ones. In this study, the effects of fluoride concentration and pH value on the corrosion behavior of Nb-10Ta-1Re and Ti-6Al-4V alloys in artificial saliva at 37°C were investigated by electrochemical measurements. For both alloys, electrochemical impedance spectroscopy and potentiodynamic polarization results showed that the corrosion rate increased with decreasing pH; also, increasing fluoride concentrations resulted in an increase in the corrosion rate. EIS results suggested that the oxide layer of Ti-6Al-4V alloy became porous in artificial saliva with high fluoride concentrations; on the contrary, Nb-10Ta-1Re alloy retained its compact oxide layer. Scanning electron microscopy results showed that after 5 days of immersion the oxide layer was washed away from the surface of Ti-6Al-4V alloy. For Nb-10Ta-1Re alloy; however, the polishing scratches were evident. At low pH values and high fluoride concentrations Nb-10Ta-1Re alloy showed better corrosion resistance in comparison with Ti-6Al-4V alloy.

Titanium alloys are used in odontology applications owing to their excellent biocompatibility. The corrosion resistance of titanium alloys is an important component of their biocompatibility. In this study, the electrochemical corrosion resistance of Ti6Al4V, Ti6Al7Nb, Ti6Al2Nb1Ta1Mo, Ti5Al2,5Fe and commercial titanium in Afnor saliva was investigated. Maintaining titanium and Ti6Al7Nb alloy in Afnor saliva for 7 days results in the formation of a protective layer, the resistance of which is high and could be comparedwith that of a passive layer resulting from electrochemical treatment. The replacement of vanadium with niobium or iron favours the passivation, thus increasing the corrosion resistance.