SURFACE-ANALYSIS OF NICKEL-TITANIUM ARCHWIRE USED IN-VIVO

Objectives. The surface quality of an archwire is a critical factor in the prevention of corrosion. This study was conducted to evaluate and assess the surface of as-received and used nickel-titanium archwires for evidence of corrosion, and to analyze possible corrosion products. Methods. Round 0.4 mm and square 0.4 mm x 0.55 mm nickel-titanium arc hwires from two manufacturers were subjected to elemental analysis, ex amined, and photographed in a scanning electron microscope with an EDA X unit. The used wires had been in service from 3 wk to 4 mon. There w ere no systematic differences in surface topography or composition bet ween the as-received and used wires. Results. The examination revealed undulated surfaces with manufactural scratches and crevices. The surf ace quality within the same archwire varied slightly, with different s moothness in the anterior and posterior regions. No systematic discern ible difference was found between used and as-received arch wires. The analyses of different areas on the used archwires revealed no differe nces in the metal composition. Significance. The surface defects found on the as-received wires were evidently not large enough to act as si tes for corrosion attack.