Nitinol And Stainless Steel Wire Case Study

The fixed orthodontic appliances are subjected to corrosive damage which acts to degrade the physical properties and increase the potential for failure. The oral environment because of its enzymatic phenomenon is an ideal climate for corrosive attack of orthodontic appliances. This gradual destruction of materials resulting from chemical reactions can have several adverse effects such as the release of elements from metals, roughening of wire surface, and weakening of appliances, which can lead to mechanical failure or even fracture of the orthodontic materials. Corrosion of orthodontic wires is strongly related with the acidic environment of buccal cavity and presence of fluoride ions, prophylactic agents and mouthwash solutions.
The
In this study only Nitinol archwire is subjected to anodic solution. The sample consists of eleven stainless steel wires and eleven Nitinol wires after being in clinical use from one to eight months. The used wires, unused portion of Nitinol and stainless steel wires and Nitinol wires which had been subjected to anodic dissolution for two minutes were mounted for SEM observations. The results of the study demonstrated that unused nitinol wire showed large variations in surface texture when compared to stainless steel wire. SEM studies showed no discernible difference in surface morphology between Nitinol wire before and after anodic dissolution. No pits were observed on either Nitinol or stainless steel wires after clinical use. The conclusion was drawn that there was no evidence to support that Nitinol wires have a higher corrosive potential than stainless steel wire. Other authors state that Nitinol is more prone to corrosion than stainless
The SEM examination of the pre and post polarized alloy surfaces provided evidence which was consistent with the electrochemical measurements, in that the first three alloys exhibited no appreciable corrosion damage whereas pitting corrosion was observed on Nitinol. The results obtained from x-ray analysis of the pitted surface indicated that this pitting could be due to selective dissolution of nickel from