The European Journal of Orthodontics Advance Access originally published online on January 20, 2006
The European Journal of Orthodontics 2006 28(3):298-304; doi:10.1093/ejo/cji102
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Galvanic corrosion between orthodontic wires and brackets in fluoride mouthwashes
* L.E.I.B.O, Faculty of Odontology, UCBL, Lyon, CNRS, Saint Martin d'Hères, France
** LEPMI National Polytechnic Institute of Grenoble, CNRS, Saint Martin d'Hères, France
Address for correspondence Dr N. Schiff, Faculté d'Odontologie, Laboratoire d'Etude des Interfaces et des Biofilms en Odontologie, rue Guillaume Paradin, F-69372 Lyon cedex 08, France. E-mail: charmant.som{at}wanadoo.fr
The aim of this investigation was to determine the influence of fluoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution of FusayamaMeyer artificial saliva and in two commercially available fluoride (250 ppm) mouthwashes, Elmex® and Meridol®. Corrosion resistance was assessed by inductively coupled plasma-atomic emission spectrometry (ICP-MS), analysis of released metal ions, and a scanning electron microscope (SEM) study of the metal surfaces after immersion of different wire-bracket pairs in the test solutions. The study was completed by an electrochemical analysis.
Meridol® mouthwash, which contains stannous fluoride, was the solution in which the NiTi wires coupled with the different brackets showed the highest corrosion risk, while in Elmex® mouthwash, which contains sodium fluoride, the CuNiTi wires presented the highest corrosion risk. Such corrosion has two consequences: deterioration in mechanical performance of the wire-bracket system, which would negatively affect the final aesthetic result, and the risk of local allergic reactions caused by released Ni ions.
The results suggest that mouthwashes should be prescribed according to the orthodontic materials used. A new type of mouthwash for use during orthodontic therapy could be an interesting development in this field.