Electrochemical Behavior of Titanium in Artificial Saliva: Influence of pH

Electrochemical behaviour of titanium and dental alloys in artificial saliva

A comparative study of the corrosion resistance of CoCr and NiCr alloys in artificial saliva (AS) containing tryptic soy broth (Solution 1) and Streptococcus mutans (S. mutans) species (Solution 2) was performed by electrochemical methods, including open circuit potential measurements, impedance spectroscopy, and potentiodynamic polarization. The adherence of S. mutans to the NiCr and CoCr alloy surfaces immersed in Solution 2 for 24 h was verified by scanning electron microscopy, while the results of electrochemical impedance spectroscopy confirmed the importance of biofilm formation for the corrosion process. The R(QR) equivalent circuit was successfully used to fit the data obtained for the AS mixture without S. mutans, while the R(Q(R(QR))) circuit was found to be more suitable for describing the biofilm properties after treatment with the AS containing S. mutans species. In addition, a negative shift of the open circuit potential with immersion time was observed for all samples regardless of the solution type. Both alloys exhibited higher charge transfer resistance after treatment with Solution 2, and lower corrosion current densities were detected for all samples in the presence of S. mutans. The obtained results suggest that the biofilm formation observed after 24 h of exposure to S. mutans bacteria might enhance the corrosion resistance of the studied samples by creating physical barriers that prevented oxygen interactions with the metal surfaces.

To investigate the effect of pH value and fluoride ions on the corrosion resistance of pure Ti and Ni-Cr-Ti alloy in the artificial saliva. Electrochemical technique was used to measure the electric potential of corrosion (Ecorr), current density of corrosion (Icorr) and polarization resistance (Rp) of pure titanium and Ti-Ni-Cr alloy in the artificial saliva with different pH value and fluoride concentrations. After electrochemical analysis, microstructure and phase diffraction were examined by FSEM. With the lower pH value, the Ecorr and Icorr of pure titanium and Ti-Ni-Cr alloy increased, the Rp decreased, there was a significant difference (P<0.05). The Ecorr and Icorr increased markedly, the Rp significantly reduced in the artificial saliva containing 0.2% NaF (P<0.01). FSEM showed that pure titanium and Ti-Ni-Cr alloy surface corrosion, pure titanium in the artificial saliva containing 0.2% NaF was most serious. Lower pH value decreases the corrosion resistance of pure titanium and Ti-Ni-Cr alloy and the artificial saliva containing fluoride ions decreases the corrosion resistance of pure titanium.

Fretting corrosion behaviour of Ti–6Al–4V alloy in artificial saliva containing varying concentrations of fluoride ions

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.

The goal of this study was to determine corrosion behavior of three orthodontic wires based on nickel-titanium alloy (NiTi) in artificial saliva at temperature of 37 °C as function of immersion time. Following orthodontic wires were used: uncoated (NiTi), rhodium coated (Rh NiTi) and nitrified (N NiTi) orthodontic wires. Corrosion of investigated orthodontic wires were monitored by measuring of Ni2+ and Ti4+ ions released in artificial saliva by inductively coupled plasma- optical emission spectroscopy (ICP-OES) after 3, 7, 14, 21 and 28 days of immersion. Obtained results indicate that corrosion reaction of the NiTi wires in artificial saliva follows the parabolic rate law. According to the obtained values of parabolic corrosion rate constants, corrosion susceptibility of orthodontic wires decreases in the following order: Rh NiTi wire (Kp = 2.48 μg2/cm4 h) > NiTi wire (Kp = 1.6 × 10–3 μg2/cm4 h) > N NiTi wire (Kp = 6.0 × 10–4 μg2/cm4 h). These results indicate that in comparison with uncoated NiTi wire, rhodium coating significantly increases corrosion susceptibility, while nitrification effectively suppresses the release of Ni2+ and Ti4+ ions.

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

The effect of hydrogen peroxide on the electrochemical behavior of Ti and some of its alloys for dental applications

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.

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.

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.

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The aims of this study were to quantify the elements released from a Ni-Cr dental alloy in artificial saliva and saline solution and to test whether immersion time and different immersion media are factors influencing elemental release from a nickel-based dental alloy. Standard sized Ni-Cr alloy castings were put into different immersion media (saline solution or artificial saliva) randomly. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to test the elemental release of the alloy at 1, 3, 7, 30 and 82 days. The surfaces of alloy were observed by scanning electron microscope (SEM). It has been found that except Ni in the artificial saliva, all the other elements remained unchanged statistically in the first week after initial release. The accumulative elemental release showed Cr in both media and Ni in the artificial saliva increased statistically in 30-day period and Ni, Cr, Be, Al, Co increased significantly in 82 days, while Mo in both media and Co in artificial saliva were not yet detected. The total mass of elements released in saline solution was greater than that in artificial saliva. Conclusion: With the immersion time increasing，more kinds of elements were released and more amount of elements released was detected in solutions. The alloy was prone to corrosion in saline solution than in artificial Saliva.

Electrochemical behavior of Ti–Cr alloys in artificial saliva

This work involves study the effect of tobacco smoking (cigarette, water-pipe smoking) yields on the corrosion of dental alloys (Co-Cr-Mo, Ni-Cr and T i-Al-V alloy) in artificial saliva with pH=4 and temperature of 37oC. This study was performed with electrochemical technique by using potentiostat to predict the potentiodynamic polarization and cyclic polarization. Some corrosion parameters were measured for comparison among the dental alloys. Generally, the presence of tobacco smoking yields shift the corrosion rate (CR) to higher values, and the data of corrosion rate indicate that the risk of waterpipe smoking more than cigarette smoking for three dental alloys. Increasing of anodic Tafel slopes inferred that the rate of change of current with change of potential was smaller during cathodic polarization than during anodic polarization.