Nanostructural Changes in Surface of Stainless Steel Archwires Combined with Orthodontic Conventional and Self-Ligating Brackets

摘要

It is well-known that the frictional force between the archwire (AW) and the bracket reduces the efficiency of orthodontic treatment. It is affected not only by geometry of self-ligating brackets (SLBs) but also by physical changes between bracket slots and AW surfaces during sliding movement. This study observed the effect of SLBs on the surfaces of stainless steel (SS) AWs during sliding tooth movement in vivo utilizing atomic force microscope (AFM). From the first bicuspid extraction case, 0.019 × 0.025 inch SS-AWs with sliding movement were selected and four groups of SS-AWs were employed; with SS-SLBs and ceramic SLBs, conventional SS brackets and intact SS-AWs. The sections engaged with brackets of second bicuspids were cut and scanned in the air at resolution of 256 × 256 pixels, with scan speed of 1 line/sec using AFM. All the SS-AWs with sliding movement showed severe scratches caused by the fictional interaction between bracket slots and AWs. The SS-AWs interacted with SS-SLBs showed the smoothest surface roughness among the three brackets. Those interacted with conventional SS brackets showed the second smooth surface. The SS-AWs interacted with ceramic SLBs showed the roughest surface compared to the others. The findings suggest that the orthodontic treatment with SS-SLBs might be more effective than that with ceramic SLBs or conventional SS brackets.