Coating stability and surface characteristics of esthetic orthodontic coated archwires

To evaluate the coating thickness of four brands of as-received esthetic coated rectangular archwires and their surface characteristics and coating stability after 21 days of oral exposure compared to those of conventional stainless steel (SS) and nickel titanium (NiTi) ones.

The labial surface of the selected archwires was observed with a stereoscope and in a scanning electron microscope, and surface roughness was assessed with an atomic force microscope. The coating thickness of as-received wires and the percentage of coating lost on the labial surface of retrieved wires were measured using Image Pro Plus 4.5 software.

All groups showed an average coating thickness of less than 0.002 inches. After oral exposure, archwires from two groups lost all coating on the labial surface. On average, 28.71% and 72.90% of the coating was lost in each of the other two groups, and the surface roughness of the remaining coating was higher than postclinical control wires.

Coated archwires had a low esthetic value as they presented a nondurable coating. The remaining coating showed a severe deterioration and a greater surface roughness than postclinical control counterparts (conventional SS and NiTi wires).