Synthesis Characterization and Highly Protective Efficiency of Tetraglycidyloxy Pentanal Epoxy Prepolymer as a Potential Corrosion Inhibitor for Mild Steel in 1 M HCl Medium.

Anticorrosive protection efficiency of novel tetrafunctional epoxy prepolymer, namely 2,3,4,5-tetraglycidyloxy pentanal (TGP), for mild steel in 1 M HCl medium was assessed through potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), contact angle (CA), adsorption isotherm model, temperature effect and thermodynamic parameters. The synthesized TGP was characterized and confirmed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR). The inhibitory efficiencies found at lower concentration of the prepolymer TGP were85% (PDP) and 87.17% (EIS). PDP measurement illustrated that the TGP behaved as a mixed-type inhibitor in the realized solution. SEM and EDS analysis showeda significant decrease in the corrosion of the MS surface in the presence of the inhibitory prepolymer compared with the blank (1 M HCl). Langmuir adsorption isotherm is the most acceptable modelto describe the TGP epoxy prepolymer on the MS area.

Effects of sterilization and disinfection procedures on the corrosion of orthodontic ligature cutters.

OBJECTIVE: The objective of our study was to investigate the corrosion resistance of orthodontic ligature cutters subjected separately to two different sterilization procedures, namely, autoclaving and chemical disinfection with main focus on the cutting section of each instrument. MATERIALS AND METHODS: Twenty-four ligature cutters were obtained from three different manufacturers: Hu-Friedy, ETM, and Nadir & Co. The study included a control group (G0) and four experimental groups (G1-4). G1 was subjected to 50 autoclave sterilization cycles. G2, G3, and G4 were subjected to 50 chemical disinfection cycles using, respectively, Peridiol E, Hexanios G+R, and Steranios 2%. Manufacturer recommendations were followed. The instruments' blades were studied via SEM and X-ray microanalysis (EDX spectrum). RESULTS: These cutters have inserts made from various resistant alloys. SEM micrographs revealed different forms of corrosion depending on whether autoclaving or chemical disinfectant sterilization procedures were used, and depending on the alloys present. Chemical disinfection is more aggressive than autoclave sterilization, and is responsible for localized corrosion in the form of pitting. This is more detrimental to the lifespan of orthodontic cutters. CONCLUSION: Sterilization/disinfection procedures should be adapted to the chemical profile of the metal alloys present. Recommendations for use published by instrument manufacturers must be followed.

Behavior of NiTi in the presence of oral bacteria: corrosion by Streptococcus mutans.

The aim of this study was to investigate the electrochemical behavior of nickel titanium (NiTi) orthodontic wires in a solution containing Streptococcus mutans oral bacteria. In this article, we explain our choice of bacterial species before describing the culture process in artificial saliva and the precautions needed to prevent contamination by other bacteria. The electrochemical behavior of the alloy (NiTi) was analyzed electrochemically in Ringer sterile artificial saliva and in artificial saliva enriched with a sterile broth and modified by addition of bacteria. The electrochemical procedures chosen for this study were: free corrosion potential, potentiodynamic curves and impedance spectroscopy. In this way, we were able to show that the free corrosion potential of the NiTi in the Ringer solution increases with time and then stabilizes, thus passivating the alloy. We also demonstrated that colonization of the metal surface by bacteria triggered a drop in the free corrosion potential. The electrochemical impedance findings revealed no significant difference in NiTi behavior between the two media. Finally, we observed a slight difference between the two corrosion currents in favor of the bacteria-enriched solution, in which the NiTi underwent greater corrosion. These findings demonstrate the impact of acidogenic bacteria on corrosion behavior of the NiTi wires investigated. However, further research is required, notably incorporating longer immersion times in the two media.