Titanium In Artificial Saliva Research Articles

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants.

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.

Corrosion resistance in artificial saliva of titanium anodized by plasma electrolytic oxidation in Na3PO4

Abstract In order to improve the chemical and electrochemical resistance of titanium as well as its potential bioactivity, coatings were formed by using plasma electrolytic oxidation under galvanostatic conditions in a phosphate containing electrolyte. The grown anodized layers were characterized at different stages of the oxidation process, corresponding to different voltages. The structure and composition of the coatings were investigated by XRD, SEM-EDS and μ-Raman spectroscopy. The electrochemical behaviour of the coated materials was evaluated in acidified artificial saliva by using classical stationary methods and electrochemical impedance spectroscopy. Before the initiation of sparks, an inner layer is formed by a classical anodizing mechanism. This layer plays the role of barrier, improving the corrosion resistance of titanium in artificial saliva. As soon as the sparking phenomenon starts, a more compact overlayer grows. Due to the presence of large cracks, the corrosion resistance is no more improved.

Corrosion Behavior of Titanium in Artificial Saliva by Lactic Acid.

As one of the main products produced by oral microorganisms, the role of lactic acid in the corrosion of titanium is very important. In this study, the corrosion behavior of titanium in artificial saliva with and without lactic acid were investigated by open-circuit potentials (OCPs), polarization curves and electrochemical impedance spectroscopy (EIS). OCP firstly increased with the amount of lactic acid from 0 to 3.2 g/L and then tended to decrease from 3.2 to 5.0 g/L. The corrosion of titanium was distinctly affected by lactic acid, and the corrosion rate increased with increasing the amount of lactic acid. At each concentration of lactic acid, the corrosion rate clearly increased with increasing the immersing time. Results of scanning electron microscopy (SEM) also indicated that lactic acid accelerated the pitting corrosion in artificial saliva. A probable mechanism was also proposed to explain the experimental results.

Effect of Anodization on Titanium-Porcelain Bonding

The effects of anodization processes on titanium-porcelain bonding were investigated. The morphologies and phase structures were evaluated by field-emission scanning electron microscopy (F-SEM) and X-ray diffraction (XRD). The bonding strength was investigated by three-point flexure test. The corrosion resistance of titanium in artificial saliva was investigated. The SEM results showed that a titanium oxide film with submicron stripes and nano-pores could be prepared by anodization and HF acid pretreatment. This titanium oxide film increased chemical bonding and mechanical interlocking between titanium and porcelain. The anodization process also enhanced the corrosion resistance of the titanium, which led to the increase of corrosion durability of the Ti-porcelain bonding strength.

Corrosion behaviour of titanium in the presence of Streptococcus mutans

ObjectiveThe main aim of this in vitro study was to evaluate the influence of Streptococcus mutans on the corrosion of titanium. MethodsS. mutans biofilms were formed on commercially pure titanium (CP-Ti) square samples (10mm×10mm×1mm) using a culture medium enriched with sucrose. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the corrosion behaviour of CP-Ti in the presence of S. mutans in Fusayama's artificial saliva. The corrosion of biofilm-free CP-Ti samples was also evaluated in artificial saliva. Biofilms biomass was measured by spectrophotometry, using crystal violet staining, after 1, 2 and 7 days. ResultsThe OCP values recorded on CP-Ti in the presence of S. mutans (−0.3±0.02V vs. SCE) was lower than those on biofilm-free CP-Ti (−0.1±0.01V vs. SCE) after 2h of immersion in artificial saliva (p<0.05). That reveals a high reactivity of titanium in presence of S. mutans. Impedance spectra revealed the formation of a compact passive film on titanium in artificial saliva or in the presence of a 2 days old S. mutans biofilm even though the corrosion resistance of CP-Ti has decreased in presence of a S. mutans biofilm. ConclusionThe presence of bacterial colonies, such as S. mutans, negatively affected the corrosion resistance of the titanium.

Stability of plasma electrolytic oxidation coating on titanium in artificial saliva

Bioactive PEO coating on titanium with high Ca/P ratio was fabricated and characterized with respect to its morphology, composition and microstructure. Long-term electrochemical stability of the coating and Ti(4+) ion release was evaluated in artificial saliva. Influence of the lactic acid and fluoride ions on corrosion protection mechanism of the coated titanium was assessed using AC and DC electrochemical tests. The PEO-treated titanium maintained high passivity in the broad range of potentials up to 2.5 V (Ag/AgCl) for up to 8 weeks of immersion in unmodified saliva and exhibited Ti(4+) ion release <0.002 µg cm(-2) days(-1). The high corrosion resistance of the coating is determined by diffusion of reacting species through the coating and resistance of the inner dense part of the coating adjacent to the substrate. Acidification of saliva in the absence of fluoride ions does not affect the surface passivity, but the presence of 0.1 % of fluoride ions at pH ≤4.0 causes loss of adhesion of the coating due to inwards migration of fluoride ions and their adsorption at the substrate/coating interface in the presence of polarisation.

Electrochemical Behavior of Ta/TaN-Coated Titanium in Artificial Saliva for Dental Applications

Electrochemical Behavior of Ta/TaN-Coated Titanium in Artificial Saliva for Dental Applications

Simultaneous degradation by corrosion and wear of titanium in artificial saliva containing fluorides

The degradation of titanium-based oral rehabilitation systems can occur by corrosion and wear processes taking place simultaneously (tribocorrosion) and influenced by the presence of fluorides. In this study, the tribocorrosion behavior of titanium in artificial saliva solutions containing fluorides is investigated. Before sliding tests were started up, electrochemical measurements such as open circuit potential (OCP) and impedance spectroscopy (EIS) were performed to get information on the corrosion behavior of titanium in artificial saliva solutions. Then, sliding wear tests were carried out at the OCP taken by the test sample. Scanning electron microscopy and weight loss measurements were performed after the tribocorrosion tests.The presence of a compact passive surface film on titanium immersed was demonstrated in artificial saliva free of fluorides and in presence of up to 227ppm F−. However, a progressive degradation of titanium was observed at a F− concentration of 12,300ppm. Additionally, the corrosion and wear resistance of the titanium oxide film formed at a F− concentration of 12,300ppm differ from the ones obtained up to 227ppm F− reflected by a decrease of the coefficient of friction although the material loss increased. The synergism between wear and corrosion processes on titanium needs thus to be further investigated to reach a reliable prediction of the long-term behavior of titanium-based prostheses and implants in the oral cavity.

Electrochemical behaviour of TiO2 nanotube on titanium in artificial saliva containing bovine serum albumin

Titanium that has been anodised to develop a nanotubular titanium oxide film is gaining interest as a dental implant material. In the present work, the corrosion behaviour of the nanotubular titanium has been investigated and compared with that of the mechanical polished titanium in artificial saliva containing bovine serum albumin (BSA, 5 g L−1). The results indicate that the diameter of TiO2 nanotube plays an important role in controlling the potentiodynamic polarisation behaviour, and the existence of TiO2 nanotube enhances the corrosion resistance and reduces the corrosion current density, which is more beneficial to the adsorption of BSA compared with the mechanical polished titanium, leading to a notable increase in the corrosion resistance of the outer TiO2 nanotubular layer.

Electrochemical Behavior of Titanium in Artificial Saliva: Influence of pH

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.

What is the role of lipopolysaccharide on the tribocorrosive behavior of titanium?

In an oral environment, titanium dental implants are exposed to a complex degradation process which is predominantly influenced by the intermittent mechanical events (mastication), continuous exposure to varying chemical solutions (saliva and food) and formation of microbiological (biofilm). Several studies have investigated the chemical corrosion and mechanical resistance of titanium; however, very few attempted to report on the effects of combined chemical, mechanical and microbiological interactions, which simulates the oral environment. A new multi-disciplinary research area, “tribocorrosion” (a combined study of wear and corrosion), was used to address such issues. The tribocorrosive nature of titanium in artificial saliva (pH 6.5) with lipopolysaccharide (LPS) was investigated. Twenty-four titanium discs (12 mm diameter, 7 mm thickness), were divided into 8 groups (n=3) as a function of material (commercially pure titanium (cpTi) and titanium–aluminum–vanadium (TiAlV) alloy) and LPS concentrations (0, 0.15, 15 and 150 μg/ml). Sliding duration (2000 cycles), frequency (1.2 Hz) and load (20 N) parameters mimicked the daily mastication process. Electrochemical impedance spectroscopy was conducted before and after tribocorrosion to comprehend the changes in corrosion kinetics. Worn surfaces were examined using white-light-interferometry and scanning electron microscopy. Total weight loss and roughness values were calculated. LPS affected the tribocorrosive behavior of both titanium types. LPS statistically accelerated the ion exchange between titanium and saliva, and reduced the resistance of the titanium surface against corrosion (p<.05). Sliding events decreased the protectiveness of the titanium surface. In general, TiAlV exhibited better corrosion behavior, but both titanium types showed similar in total weight loss (p>.05). LPS significantly increased the cpTi weight loss (p=.041), and the roughness of the surface (p<.001). In summary, LPS negatively affected the corrosion/wear behavior of titanium, which may contribute to the failure of dental implants.

Repassivation behavior of titanium in artificial saliva investigated with a photon rupture method

Repassivation kinetics of titanium were investigated in artificial saliva by the photon rupture method, PRM, combined with anodizing. PRM uses focused pulsed Nd–YAG laser beam irradiation to remove oxide film and metal. The effects of the applied potential and F − ions on the repassivation kinetics of titanium were examined electrochemically. All conditions in this study use specimens that were repassivated within about 100 ms after the laser beam irradiation. The current transients after the laser beam irradiation showed a rapid increase, followed by a decrease with a slope of the log i vs. log t plots of about −1.5. The measured slope is steeper than what would be expected with the high field oxide film formation theory. This result suggests that the oxidation of titanium takes place through a combination of electrochemical and chemical reactions. More NaF results in a higher peak current density and amount of charge after laser beam irradiation. The influence of F − ions on the repassivation kinetics may be explained by localized pH changes caused by dissolution of titanium immediately after the laser beam irradiation.

The Effect of Mucine, IgA, Urea, and Lysozyme on the Corrosion Behavior of Various Non-precious Dental Alloys and Pure Titanium in Artificial Saliva

The corrosion of dental alloys has biological, functional, and aesthetic consequences. Various studies have shown that protein solutions can inhibit the corrosion of alloys. This study is planned to determine the relationship of organic constituents of saliva and the corrosion of dental alloys. The organic constituents are IgA, mucine, urea, and lysozyme which are encountered in the highest amounts in saliva and the dental materials are titanium (Ti), Co-Cr-Mo and Ni-Cr-Mo alloys, and dental amalgam, the most often used metallic components in dentistry. In particular, the interactions between the commonest salivary proteins, IgA, mucine, urea and lysozyme, and Ti, Co-Cr-Mo, Ni-Cr-Mo and dental amalgam were investigated. Each alloy was evaluated by cyclic polarization in each medium. The general anodic and cathodic behavior during forward and reverse cycles, the corrosion and passivation current densities (muA/cm2 ), and the corrosion and the pitting potentials (mV) were determined. The results have shown that Ni-Cr-Mo and dental amalgam alloys are highly susceptible to corrosion in all the investigated media. The Co-Cr-Mo alloy has shown high passive current densities in the solution of mucine and lysozyme in artificial saliva. Titanium instead, has shown a high resistance to corrosion and a stable passive behavior in all media, especially in a solution of mucine and IgA in synthetic saliva. Mucine and IgA, as well as urea and lysozyme, appeared to enhance the formation of a passive film layer on the Ti metal surface, thus inhibiting the corrosion. Based on the study findings, and especially considering the problem of nickel allergy and toxicity of mercury released from dental amalgam, the use of Co-Cr-Mo alloys and Ti to Ni-Cr-Mo alloys is recommended and alternatives to dental amalgam should be sought for patients with impaired salivary flow.

Influence of fluoride concentration and pH on corrosion behavior of titanium in artificial saliva

Titanium (Ti) exhibits excellent corrosion resistance in most aqueous media due to the formation of a stable oxide film and is chosen for surgical and odontological implants for this resistance and its biocompatibility. Treatment with fluorides (F) is the main method to prevent plaque formation and dental caries. Toothpastes, mouthwashes and prophylactic gels can contain from 200 to 20,000 ppm F and have neutral to acidic character, which can affect the corrosion behavior of titanium devices present in the oral cavity. In this work the behavior of Ti has been evaluated in artificial saliva of pH 2, 5 and 7 and different fluoride concentrations (0, 1,000, 5,000 and 10,000 ppm F), through open-circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy. Limits of pH value and fluoride concentration at which Ti corrosion behavior changed could be established. Active behavior was observed for pH 2 and 1,000–10,000 ppm F, and for pH 5 and 5,000 and 10,000 ppm F. The other conditions led to passive behavior. Decrease in corrosion resistance and less tendency for passivation were observed as fluoride concentration increased and pH decreased.

Influence of pH and corrosion inhibitors on the tribocorrosion of titanium in artificial saliva

Dental implants are used to replace teeth lost due to decay, trauma, or periodontal diseases. Dental implants are most of the times subjected to micro-movements at the implant/bone interface or implant/porcelain interface (due to the transmitted mastication loads) and chemical solicitations (oral environment). Such implant becomes part of a tribocorrosion system, which may undergo a complex degradation process that can lead to implant failure. In this work, the fretting–corrosion behaviour of titanium grade 2 in contact with artificial saliva was investigated under fretting test conditions. Citric acid was added to artificial saliva to investigate a pH variation on the tribocorrosion behaviour of the material. Additionally, three different inhibitors were added to investigate cathodic and anodic reactions on the electrochemical response. Also, the influence of inhibitors included in the formulation of tooth cleaning agents or medicines was investigated. Degradation mechanisms were investigated by electrochemical noise technique that provided information on the evolution of corrosion potential and corrosion current during fretting tests. Depassivation and repassivation phenomena occurring during the tests were detected and discussed. Considering the influence of corrosion inhibitors, it was observed that the degree of protection varies with the nature of the inhibitors.

Electrochemical behaviour of titanium and dental alloys in artificial saliva

The electrochemical behaviour of titanium in artificial saliva was compared to those of a gold alloy, two CoCr alloys, and a non-gamma-2 dental amalgam. The potentiodynamic anodic polarization curve of Ti has an extremely weak passivation current density (= 1.5 μA cm −2) even at high polarization potentials. No breakdown potential has been observed, at least up to 1200 mV vs. sce. Repassivation of Ti is immediate, and its corrosion resistance is very high. The galvanic currents between Ti and CoCr alloys are extremely weak. Ti also shows a low sensitivity to crevice corrosion. When corrosion is uniform or localized, Ti has a nearly identical or better behaviour than CoCr alloys in artificial saliva.

Corrosion of gold alloys and titanium in artificial saliva.

Two types of gold alloys and one type of pure titanium have been submitted to corrosion in artificial saliva for periods of up to about 2 months. The release of copper, gold or silver from the gold alloys as well as titanium from the titanium matrix was measured with nuclear tracer technique. The physical/chemical state of the corrosion products of gold alloys referring to the ionic state or presence in particulate form has been examined retaining the particulate matter on a glass filter. Copper was observed to be mainly present in the ionic state. Considerable amounts of gold were observed to be retained on the glass filter explained by the presence of gold in particular form or as a component of a dispersed colloidal phase. The estimation of the release of titanium was registered by the tracer nuclide 46Sc assuming particulate matter to be deteriorated from the titanium surface.