engleski

Poor oral hygiene, oral antiseptics and orthodontics: corrosive implications of nickel-titanium archwires

Aim: The excellent corrosion resistance of titanium alloys results from the formation of very stable, protective titanium oxide (TiOx) films on metal surfaces. The study aimed to explore the effect of oral antiseptics in low pH environment on the deterioration of protective TiOx films of nickel-titanium (NiTi) archwires. Materials and Methods: Three type of NiTi wires (uncoated, rhodium-coated and nitrified) were immersed in artificial saliva (pH 4.8, 37°C) during 28 days. Wires were immersed once-a-week for a period of 5 minutes in antiseptics based on hyaluronic acid (Gengigel), chlorhexidine (Curasept) and essential oils (Listerine). Wires immersed only in artificial saliva served as negative control. Corrosion was monitored by measuring of Ti4+ ions released in artificial saliva by inductively coupled plasma-optical emission spectroscopy after 3, 7, 14, 21 and 28 days. Mechanical characteristics were measured by a 3-point bend test in unexposed wires and in wires after the completion of immersion. Results: In nitrified wires all antiseptics induced similar titanium release as pure saliva did. In uncoated wires, the most evident release of Ti4+ ions was during the first three and last seven days of immersion in Gengigel, when compared to Listerin and saliva (p<0.05). In rhodium-coated wire, Listerin and Curasept induced higher release of Ti4+ ions than saliva and Gengigel. Mechanical characteristics were partially related to titanium release. All antiseptics increased modulus of elasticity in load and unload in uncoated wires in comparison to saliva. This was most pronounced in Gengigel, who also reduced yield strength in both load and unload. Conclusion: Corrosion of NiTi is related to type of antiseptic and wire coating.

corrosion; NiTi wires; anstiseptics

FInancirano potporom Sveučilišta u Rijeci 13.06.2.1.53