Electropolymerization of poly(N-ethyl aniline) on mild steel: Synthesis, characterization and corrosion protection

Electrochemical Behavior of Ti6Al4V Alloy Used in Dental Implants Immersed in Streptococcus gordonii and Fusobacterium nucleatum Solutions

The titanium alloy, Ti6Al4V, is used in dentistry for dental implants because of its excellent resistance to corrosion and its high biocompatibility. However, periimplantitis is considered the main reason for treatment failure. The Ti6Al4V alloy was used to study the corrosion behavior for dental implant applications, using an experimental arrangement of three electrodes with the bacteria Streptococcus gordonii and Fusobacterium nucleatum, in addition to Ringer's lactate as electrolytes, at 37 °C and a pH of 5.6. Their electrochemical behavior was studied by open circuit potential (OCP) and cyclic potentiodynamic polarization (CPP) according to ASTM G3-14 and ASTM G61-11, respectively. Scanning electron microscopy (SEM) was employed to determine the morphology of the alloy studied. An experimental model, in situ, was established with the bacteria present in an oral environment to understand the electrochemical behavior of the alloy used in dental implants. The greatest corrosion in Ti6Al4V alloy was produced by the medium that contained the bacterium Streptococcus gordonii, which is considered a primary colonizer. In addition, the Ti6Al4V alloy presented uniform corrosion in the three solutions at the different exposure times showing a negative hysteresis in CPP.

Corrosion resistance assessment of Co-Cr alloy frameworks fabricated by CAD/CAM milling, laser sintering, and casting methods

STATEMENT OF PROBLEM

The effects of fabrication methods on the corrosion resistance of frameworks produced with Co-Cr alloys are not clear.

PURPOSE

The purpose of this in vitro study was to evaluate the electrochemical corrosion resistance of Co-Cr alloy specimens that were fabricated by conventional casting, milling, and laser sintering.

MATERIAL AND METHODS

The specimens fabricated with 3 different methods were investigated by potentiodynamic tests and electrochemical impedance spectroscopy in an artificial saliva. Ions released into the artificial saliva were estimated with inductively coupled plasma-mass spectrometry, and the results were statistically analyzed. The specimen surfaces were investigated with scanning electron microscopy before and after the tests.

RESULTS

In terms of corrosion current and Rct properties, statistically significant differences were found both among the means of the methods and among the means of the material groups (P<.05). With regard to ions released, a statistically significant difference was found among the material groups (P<.05); however, no difference was found among the methods. Scanning electron microscopic imaging revealed that the specimens produced by conventional casting were affected to a greater extent by etching and electrochemical corrosion than those produced by milling and laser sintering.

CONCLUSIONS

The corrosion resistance of a Co-Cr alloy specimens fabricated by milling or laser sintering was greater than that of the conventionally cast alloy specimens. The Co-Cr specimens produced by the same method also differed from one another in terms of corrosion resistance. These differences may be related to the variations in the alloy compositions.

Construction and electronic properties of carbon nanotube hybrids with conjugated cubic silsesquioxane

Hierarchical zero-dimensional cubic silsesquioxane/one-dimensional SWNT hybrids provided excellent charge transfer and synergistic effects compared to both SWNTs and OASQ.

The electrochemical properties of four dental casting suprastructure alloys coupled with titanium implants

Objectives:

As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions.

Material and Methods:

The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests.

Results:

The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples.

Conclusions:

Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.