Miniscrews for orthodontic anchorage: nanoscale chemical surface analyses.

OBJECTIVES The goal of this study was to determine the chemical composition of the passivation layer of three clinically available orthodontic miniscrews at different depths. MATERIALS AND METHODS The miniscrews used were Aarhus Mini-Implant (AAR), IMTEC Ortho (IMT), and VectorTAS (VEC). The chemical compositions of the as-received miniscrews were determined by X-ray photoelectron spectroscopy (XPS). Data was acquired before etching the miniscrews with argon, as well as after etching at depths of 10 nm, 20 nm, 30 nm, and 80 nm. RESULTS The elements found in all miniscrews were mainly C, O, and Ti. Also found were other metals in small amounts, and other trace elements. All three miniscrews showed very different characteristics in surface composition. IMT had the greatest increase in Ti, as well as the most titanium metal at 80 nm. VEC remained stable at all tested depths and contained no titanium metal at 80 nm. AAR was an intermediate between the two. CONCLUSIONS The passivation layer of the orthodontic miniscrews has different compositions depending on the brand, as well as the depth analyzed. VEC appeared to have the largest passivation layer, and IMT appeared to have the thinnest passivation layer.