Comparison of metal ions release and corrosion potential from different bracket archwire combinations (An in vitro study)

Abstract

Background: Esthetic treatment is the options of patient seeking orthodontic treatment. Therefore this study wasconducted to measure the concentration of Aluminum, Nickel, Chromium and Iron ions released from combinationof monocrysralline brackets with different arch wires immersed in artificial saliva at different duration, to evaluate thecorrosion point on different parts of the orthodontic appliances before and after immersion in artificial saliva, and toevaluate the corrosion potential of each group of the orthodontic appliances.Material and methods: Eighty orthodontic sets prepared. Each set represents half fixed orthodontic appliance, fromthe central incisor to the first molar, for the maxillary arch, each set consisted of molar band, five brackets, half archwire and ligature elastic.These sets are divided into two groups: Group A: with monocrystalline brackets divided intofive subgroups (each subgroup has ten sets), but differ in arch wires, as numbered stainless steel, nickel-titanium,thermally activated, coated stainless steel and coated nickel-titanium arch wires respectively. Group B: with stainlesssteel brackets divided into three subgroups (also each subgroup has ten sets), but differ in arch wires, asnumberedstainless steel, nickel-titanium, and thermally activated arch wires respectively. Used optical microscope tocheck the corrosion points, and used potentiostat techniques to indicate corrosion rate and tendency.Results: The greatest concentration of Aluminum and nickel ions release during the 1st week in group A, then sharplydecreased in the 2nd week. The release of chromium ion released increase with increase intervals, while iron ionreleased decrease with increase time. Both nickel and chromium ions increase with increase intervals in group B,whileiron increase to the maximum at 3rd weeks, then began to degrease. Optical microscope displayed pitting, crevices,and intergranular corrosion. Potentiostat techniques indicated that increase corrosion when used stainless steel andcoated nickel titanium than others arch wires with group A, while corrosion increase with nickel titanium than stainlesssteel arch wires with group B.Conclusions: Non-significant difference in the total nickel, chromium and iron release in group B. Aluminum and ironincrease in A4 and A5, while nickel and chromium increase in A1 and A2.The total released amounts of metals ions inboth groups were less than the amounts of daily intake