An investigation into the mechanical and aesthetic properties of new generation coated nickel-titanium wires in the as-received state and after clinical use.

The orthodontic profession is constantly seeking to improve and optimize the aesthetics of orthodontic wires since the introduction of aesthetic brackets. Nickel-titanium (NiTi) wires since their introduction to orthodontics (Andreasen and Hilleman, 1971) have been extensively researched in vitro and are used as an initial levelling and aligning archwire because of its properties of springback and superelasticity (Burstone et al. , 1985; Miura et al. , 1986; Leu et al. , 1990; Bishara et al. , 1995; Bradley et al. , 1996; Biermann et al. , 2007; Berzins and Roberts 2010). Aesthetic wires are usually either coated NiTi wires or composite wires of reinforced polymers. Shape memory polymers have wide application in space technology and are being used currently in medicine and industrial applications (Jung and Cho, 2010; Hu et al. , 2012). These wires have enormous potential for clinical application in orthodontics, and polyphenylene, a self-reinforced polymer composite, is close to being introduced to orthodontic practice (Burstone et al. , 2011; Goldberg et al. , 2011). However, these wires are still at the experimental stage. A fibre reinforced polymer is in clinical use (BioMers Products, LLC, Jacksonville, FL, USA) that is manufactured using a pultrusion process with a photo-cured resin (Gopal et al. , 2005); however, these wires may be more likely to crack during bending and have been shown to deliver less consistent forces compared with alloy wires (Chang, 2012). The coated wires, which are currently available, either have an epoxy resin, polytetraflouroethylene (Teflon; Neumann et al. , 2002), or a low reflectivity rhodium coating (Iijima et al. , 2012) applied to the surface. Atomized Teflon particles are used to coat the wire using clean compressed air as a transport medium, which is then further heat treated in a chamber …