Comparison of coating stability and surface characterization of different esthetic NiTi arch wires – An in vivo study

Abstract

The article aimed to compare the coating stability and surface characterization of different esthetic nickel-titanium (NiTi) archwires. A total of 48 esthetic NiTi archwires were categorized into four groups based on the type of coating material that was selected and studied (Groups: I. Epoxy coated, II. Polymer coated, III. Teflon coated, and IV. Rhodium coated). These wires were ligated in patients undergoing fixed mechanotherapy in the department. The surface details and coating stability were studied in the wires removed from patient’s mouth after 21 days using 3D profilometer, scanning electron microscope (SEM), and stereomicroscope. A maximum percentage of coating loss was observed in Group II (epoxy coated) and the minimum in Group III (polymer coated). Maximum surface roughness was observed in Group II (epoxy coated) and minimum in Group III (polymer coated). The average coating thickness of as received wires was observed to be 0.002” in dimension. All the wires had low esthetic values, as they presented a non-durable coating after oral exposure. On visual examination of SEM image, all four group esthetic wires showed variations ranging from microcracks and large sized striations to overall destruction of coating regularity.