Corrosion resistance of surface modified nickel titanium archwires

Abstract

Surface modification of NiTi wires proved to be effective in improving its corrosion resistance and decreasing surface roughness. However, neither factor could maintain a direct, one-to-one relationship. It meant that the type and nature of coating material can effectively influence the anticorrosive features of NiTi wires, compared with its surface roughness values.

In vitro biocompatibility of nickel-titanium esthetic orthodontic archwires

“…More specifically, Titanol Cosmetic archwires have a classical Teflon coating, whereas BioCosmetic archwires are manufactured through an innovative procedure: the metallic core is embedded in a flexible material instead of being sprayed by color particles, which usually happens for the majority of polymercoated archwires present in the market. It has been shown 22 that Teflon coating was able to improve the corrosion resistance of NiTi archwires better than does resin coating. Moreover, titanium discs with a Teflon coating had no toxic effects on MG-63 osteoblasts, 23 shown by higher expression levels of the alkaline phosphatase (ALP), osteocalcin (OC), and OPG/ RANKL ratios in cells grown on polytetrafluoroethylene (PTFE) surface in comparison to those cultured on an uncoated titanium surface.…”

Influence of surface layer on mechanical and corrosion properties of nickel-titanium orthodontic wires

“…32 Various research has found a variety of results for surface roughness parameters, and simple conclusions cannot be made regarding friction, because Ra depends on both wires' and brackets' design and material. 9,16,18,33 Also, previous research suggests that the type of material and the manufacturing process influence corrosion properties more than surface roughness parameters alone. 17,28 Furthermore, additional investigation is necessary to clarify whether the above observed differences are the sole results of the coating or if they are influenced by the coating's manufacturing process.…”

“…14,15 The surface roughness of archwires in orthodontics is still considered a controversial parameter as far as its relation to friction and corrosion are concerned as well as its relation to clinical use. 5,[16][17][18] Uncoated NiTi wires have titanium oxides (TiO x ) as anticorrosive components; rhodium-coated NiTi (Rh NiTi) has gold and rhodium in a 0.5-mm thin layer (as stated by the manufacturer). Both are noble metals and form a protective surface layer.…”

“…It is common to perform in vitro studies of corrosion processes using electrochemical methods [5][6][7]17,18,21,22 because the release of metal ions within the oral cavity occurs over a long period and is associated with discoloration of adjacent structures and teeth as well as allergic and toxic reactions. 14,15 Electrochemical impedance spectroscopy (EIS) testing determines the polarization resistance, a direct measure of corrosion resistance; cyclic polarization testing helps in the observation of the pitting tendencies of the alloy; and in vitro anodic polarization studies simulate the natural corrosion mechanism that usually happens over a protracted duration of time.…”

Corrosion resistance and mechanical properties of titanium nitride plating on orthodontic wires

“…NaCl solution was deaerated with N 2 gas at 40°C for 1 h. Anodic polarization tests were carried out in 0.9% NaCl solution at 37°C with a potentiostat (HZ-5000, Hokuto Denko, Tokyo, Japan) started from the −0.4 to 1.0 or 2.0 V at a scan rate of 0.6 mV/s, and the polarization curve of each wire was recorded to measure the breakdown potential. The potential at which there was a sharp increase in anodic current density in the curve was taken as the breakdown potential 16) . Four replicates of each wire were tested.…”