The study “Comparison of the Superelasticity of different nickel-titanium orthodontic archwires and the loss of their properties by heat treatment” led by Dr Andreu Puigdollers, head of the Orthodontics Area at the Faculty of Dentistry, and Dr Xavier Gil, researcher at the Bioengineering Institute of Technology, has received recognition from the Journal of Material Science: Materials in Medicine for being one of its most downloaded scientific articles in 2020.

Published in 2016, the study led by the researchers from UIC Barcelona makes a comparative analysis of the mechanical properties of eight nickel-titanium archwires widely used in the field of orthodontics, and determines the influence heat treatment has on the loss of superelasticity. During the investigation, the team assessed ten archwires from two sets of eight different manufacturers.

In all cases, heat treatment at 600°C produced precipitation in the matrix, causing changes to the chemical composition and the loss of superelasticity. At 400°C, these precipitates are not produced and the forces delivered by the wires are very similar with untreated wires.

“It is important to understand the mechanical behaviour of an orthodontic archwire in order to select the appropriate size and material that will give the treatment optimal and predictable results”, explain the researchers. Therefore, nickel-titanium archwires must be selected due to their load-deflection, depending on the treatment phase, degree of deflection, periodontal support and the desired type of movement. As the study shows, the heat treatments used to modify the original shape, produce Ni-rich precipitates that prevent superelasticity.