[The surface roughness of orthodontic wires--a laser optical and profilometric study]

The surface roughness of orthodontic wires is an essential factor that determines the effectiveness of arch guided tooth movement. Using the nondestructive technique of laser specular reflectance, the surface roughness of 11 nickel titanium orthodontic wires and a standard steel as well as a beta-titanium wire was measured. The results were compared with the results from surface profilometry. The smoothest wire, standard steel Hi-T, has an optical roughness of 0.10 microns, while the roughness from profilometry reached a value of 0.06 microns. The titanium molybdenum wire has an optical as well as a profilometric roughness of about 0.20 microns, while the roughness of the NiTi wires ranges from 0.10 microns to 1.30 microns. As the surface roughness not only influences the effectiveness of sliding mechanics, but also the corrosion behaviour and aesthetics, the manufacturers of orthodontic wires are asked to improve the surface quality of their products.