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 Ni 2+ and Ti 4+ 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 (K p = 2.48 μg 2 /cm 4 h) > NiTi wire (K p = 1.6 × 10 -3 μg 2 /cm 4 h) > N NiTi wire (K p = 6.0 × 10 -4 μg 2 /cm 4 h). These results indicate that in comparison with uncoated NiTi wire, rhodium coating significantly increases corrosion susceptibility, while nitrification effectively suppresses the release of Ni 2+ and Ti 4+ ions.

Aim was to determine effect of pH, fluoride (F − ) and hydrofluoric acid concentration (HF) on dynamic of nickel (Ni 2+ ) and titanium (Ti 4+ ) ions release. Nickel-titanium wires with untreated surface (NiTi), rhodium (RhNiTi) and nitride (NNiTi) coating were immersed once a week for five min in remineralizing agents, followed by immersion to artificial saliva. Ion release was recorded after 3, 7, 14, 21 and 28 days. Pearson correlations and linear regression were used for statistical analysis. Release of Ni 2+ from NiTi and NNiTi wires correlated highly linearly positively with HF (r=0.948 and 0.940, respectively); for RhNiTi the correlation was lower and negative (r=−0.605; p<0.05). The prediction of Ti 4+ release was significant for NiTi (r=0.797) and NNiTi (r=0.788; p<0.05) wire. Association with F − was lower; for pH it was not significant. HF predicts the release of ions from the NiTi wires better than the pH and F − of the prophylactic agents.

No abstract

No abstract

No abstract