Comparative Evaluation of Silver Dioxide-Coated and Noncoated Stainless Steel Wires for Susceptibility to Corrosion:...

Stainless steel (SS) orthodontic archwires are widely used because of their mechanical properties, affordability, and biocompatibility; yet, prolonged intraoral exposure can cause electrochemical corrosion and release of metal ions (eg, Ni and Cr) that may affect clinical performance and patient safety. Surface coatings such as silver dioxide have been proposed to improve corrosion resistance, but comparative data for silver dioxide-coated versus uncoated SS orthodontic archwires across clinically relevant simulated oral environments are lacking.

This study aimed to compare the corrosion susceptibility of silver dioxide-coated and noncoated 0.019"×0.025" SS orthodontic archwires in four simulated oral solutions by measuring electrochemical behavior, cumulative metal ion release, and mass lossthereby testing our null hypothesis (H₀) that no difference exists between coated and noncoated wires.

This in vitro protocol uses 40 SS archwire specimens divided into two main groups (20 silver dioxide-coated, and 20 uncoated) and four immersion subgroups (n=5 per subgroup): (1) 0.9% NaCl, (2) phosphate-buffered solution acidified with lactic acid (pH ~6.75), (3) phosphate-buffered solution with 0.1 wt% NaF, and (4) phosphate-buffered solution with 0.1% w/v bovine serum albumin. Coatings will be deposited by radiofrequency magnetron sputtering to achieve a 15- to 20-nm silver oxide (Ag₂O/AgO) layer; coating quality will be verified through scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and profilometry. Specimens will be incubated individually at 37 °C with orbital agitation; immersion solutions will be sampled at baseline, 14 days, and 28 days. The primary outcome is corrosion current density (Icorr, µA/cm²) from potentiodynamic polarization. Secondary outcomes include pitting potential (Epit, mV vs SCE), cumulative ion release (Ag, Ni, Cr, Fe; expressed µg/mm²) analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) after acidification, percent weight loss normalized to surface area (mg/cm²), and SEM/EDS surface analyses. Electrochemical tests will follow a standardized three-electrode setup (SCE reference). Statistical analyses will be used to assess normality; we will use independent-samples tests or nonparametric equivalents for between-group comparisons and mixed-effects models for time-dependent measures. Tests were evaluated at α=.05, with effect sizes and 95% CIs reported throughout.

Institutional ethical approval was obtained in April 2024 (DMIHER(DU)/IEC/2024/253). Coating parameters and quality control procedures have been established, and 40 specimens have been prepared and characterized. Immersion and electrochemical experiments are scheduled between June and December 2025, followed by ICP-OES analysis and statistical evaluation, with study completion planned by December 2025.

This protocol will generate comparative data on electrochemical corrosion, ion release, and material degradation of silver dioxide-coated versus uncoated SS orthodontic archwires under multiple simulated oral conditions. Our findings will inform the potential of silver dioxide coatings to enhance the durability and biocompatibility of orthodontic archwires and will guide future in vivo or clinical investigations.