Mechanical Performance of Nickel-titanium Archwires

Daniel Jogaib Fernandes,Rafael Vidal,Carlos Nelson Elias,Alvaro De Moraes Mendes

doi:10.1590/1516-1439.003615

Daniel Jogaib Fernandes, Rafael Vidal + Show 2 more

Open Access

https://doi.org/10.1590/1516-1439.003615

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Abstract

The purpose of the present work is to compare the mechanical properties of commercially available NiTi orthodontic archwires lots. Superelastic (SE) and heat-activated (HA) NiTi archwires from two lots of six manufacturers (3M, GAC, Tp, Orthosource, Orthometric and Morelli) were partitioned into eleven groups (n=132) and tested under three-point bending tests. The difference between the highest (151.35 gf, Tp) and lowest (98.43 gf, 3M) unloading stresses among SE groups was 53.77% (p .05), whereupon there are equivalences in wires commercial offered at different costs.

Highlights

NiTi alloys are currently used for biomedical purposes because of their superelastic (SE) behavior, which can reach more than 10% strain during tension, the one way (1way) effect, good corrosion resistance and biocompatibility[1]
Besides that, considering the superelasticity may not exhibit a clearly discernible unloading plateau when testing in bending, the objective of this study is to evaluate the loading/unloading behavior under bending of six brands of superelastic and heat activated orthodontic archwires and compare their performance
The difference in SE between the highest (900.37 + 18.46 MPa, Tp) and lowest (585.52 + 31.75 MPa, 3M) unloading stresses among the 11 groups was 53.77%, while the difference between HA group was 168.20%. The fact that this difference is very high means that it is difficult to apply an adequate force to the teeth during an orthodontic treatment

Summary

Introduction

NiTi alloys are currently used for biomedical purposes because of their superelastic (SE) behavior, which can reach more than 10% strain during tension, the one way (1way) effect, good corrosion resistance and biocompatibility[1]. These properties lead to a wide use in many applications, such as medical implants, stents and orthodontic wires[2]. NiTi wires attend the requirements for an archwire performance, which include low elastic modulus, high flexibility, minimal plastic deformation, resistance to fatigue, good corrosion resistance and production of constant small forces over a wide range of displacements[3]. Note the degree of misalignment and unleveling that the wire can tolerate due to superelastic properties

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