An Electrochemical Study On Corrosion Behavior Of General Alloy Of Orthodontic In Artificial Saliva

Objective: After detecting the electrochemical parameter of orthodontic brackets coupled with three different kinds of orthodontic arch wires, to get the composite evaluation of the corrosion itself and the character of the galvanic corrosion. So that we can find out the different types of the general alloy of orthodontic and the inflection to the alloy corrosion prevention from the fluorion.Methods: Adopt the classic three-electrodes system of electrochemical method to detect the corrosion potential and corrosion current density of general orthodontic stainless steel brackets, NiTi-archwire, ?-Ti- archwire and CoCr- archwire,so that we can find out the reaction of corrosive by itself in artificial saliva. On that basis, detecting galvanic couple current density by coupling the brackets with those three kinds of arch wires separately in the different fluoride concentration. And then, we can study the phenomenon of galvanic corrosion. Results:1. In the artificial saliva, the sequence of corrosion potential of brackets and three arch wires was SS>CoCr>?-Ti>NiTi; the sequence of corrosion current density was NiTi>?-Ti>CoCr>SS. The statistic results of each group had significant difference(P<0.01).2. In the artificial saliva, the sequence of current density of three galvanic couples was SS+NiTi>SS+ ?-Ti>SS+CoCr. The statistic results of each group had significant difference(P<0.01).3. In different fluoride concentration artificial saliva , the sequence of current density of three galvanic couples was SS+NiTi>SS+ ?-Ti>SS+CoCr. Compare each other ,the statistic results had significant.4. For each couple, the largest current density was in the artificial saliva which fluoride concentration was 2%, the smallest one was in the artificial saliva which fluoride concentration was 0%.Conclusion:1. In artificial saliva, orthodontic alloy will always tend to electrochemical corrosion, and then produce relative corrosion current. 2. In artificial saliva, after the brackets be combined with three kinds of arch wires. All of them will produce relative galvanic corrosion current. Due to the biggest corrosion potential of orthodontic brackets ,having coupled with arch wires,it will be protected as cathode. And then, the counter-party will turn to be anodes with higher corrosion speed.3. During this certain test, all the coupling by the brackets with those three kinds of arch wires separately have been suffered different levels influence. The reaction of the coupled type of brackets with CoCr- arch wire is obvious lower than the other two kinds. It means the most excellent corrosive features.4. The fluorion could speed up the reaction of the couple combination of brackets with orthodontic arch wire. The higher density,the worse reaction.