Functionally Graded Orthodontic Archwires - Production And Characterization Francisco M. Braz Fernandes, Patrícia Freitas Rodrigues, Rafaella Magalhães, Edgar Camacho CENIMAT / I3N - Departamento Ciência dos Materiais, Universidade Nova de Lisboa / FCT, 2829-516 Caparica, Portugal Patrick Inácio, Telmo Santos UNIDEMI – Departamento de Engenharia Mecânica e Industrial, Universidade Nova de Lisboa / FCT, 2829-516 Caparica, Portugal Norbert Schell High Energy Materials Science, PETRA-III, DESY, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max Planck-Str. 1,21502, Geesthacht, Germany Introduction The introduction of graded functionality in commercial superleastic orthodontic archwires (Morelli SE) was analyzed. There are few studies concerning the manufacturing of the functionally graded Ni-Ti orthodontic archwires reported in the literature. The load developed by these wires depends on the geometrical characteristics, the temperature and the strain. Normally, the conventional archwires generate constant forces in a wide range of displacement during the orthodontic treatment [1]. In order to have different forces of actuation in the incisive region (lower) and in the molar region (higher), different fabrication strategies have been proposed, such as (i) laser welding different wire segments [2], or (ii) separate heat treatment of different segments in a special furnace [3]. In the present study, a functional gradient was introduced in a superelastic Ni-Ti orthodontic archwire (Morelli - SE) by localized heat treatment using Joule heat effect. DSC measurements at different positions of the wire show that a microstructural gradient is present in such treated archwires (Fig. 1-a). A localized analysis along the heat-treated archwire, using synchrotron radiation based X-ray diffraction (SR-XRD) was used to identify the microstructure of the heat treated archwire with a finer spatial resolution (Fig. 1-b). Experimental results Figure 1 - Ni-Ti orthodontic archwire heat treated at 300 ºC during 10 min: (a) DSC curves of the three zones of the wire, where internal is the central part (16 mm) of the heat-treated zone (32 mm), transition is the intermediate zone (~8mm) between the central uniformly heated (16 mm) and non heat treated segment ( external). (b) SR-XRD along the Ni-Ti orthodontic wire.