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Analysis of chemical composition of the surface and elasticity of nickel-titanium alloy after exposure to fluoridated re-mineralizing agents

Aim:To explore the effect of fluoridated enamel remineralisation agents on the chemical composition of the surface and elasticity of nickel-titanium archwires with various coatings. Materials and Methods: Uncoated (NiTi), rhodium-coated (RhNiTi) and titianium nitride coated (NNiTi) nickel-titanium wires (dimension 0.508 mm × 0.508 mm) were tested. Ten samples from each wire type were immersed for 1 hour at 37° into Mirafluor-k-gel, Elmex gelèe and MI Paste Plus. Wires immersed in distilled deionized water (dH2O) served as negative control. Three-point bend test was used to assess flexibiliy and resilience in load and unload. Chemical composition of surface was analyzed with the energydispersive spectroscopy. Results: Exposure of NNiTi to fluorides and dH2O induced significant decrease of flexibility in load in comparison to as- received condition (p<0.001). Resilience decreases in MiPaste and Mirafluor in load (p=0.004). In RhNiTi MiPaste, Mirafluor and dH2O increase flexibility in load in comparison to as-received condition (p=0.006), and Mirafluor and dH2O in unload (p=0.001). Flexibility of NNiTi did not change. The nickel and titanium was recorded for the both coated wires, indicating the very thin surface layers. Conclusions: Commercial fluoride agents do not decrease unloading elastic properties of orthodontic archwires and will not affect tooth movement, regardless coating of wire’s surface. Surface coatings deteriorate after immersion to fluridated agents.

topical fluoride agents ; surface coating ; NiTi wires ; elasticity

IP-2014-09-7500