Innovative Integration: a new 3D-Printed Orthodontic Clear Aligner With Wire

Abstract

<p><strong>Objectives</strong>: This study investigates the static mechanical test and dynamic mechanical analysis of new orthodontic clear aligner combined with surface modified stainless steel orthodontic wires using 3D printing technology. The interfacial strength, tensile strength, and stress relaxation are compared.<br><strong>Methods</strong>: Stainless steel wire samples are divided into 3 groups with different surface treatments: control groups (C), sandblasting group (S), sandblasting, and acid etching group (SA). The disc-shaped test samples (n=10 each) for pull out test are prepared in the PTFE mould (D: 16.0 mm, t: 2.0 mm). Design and print the samples for tensile (n=10) and stress relaxation (n=3) and modified stainless steel wire is embedded in the specimens during 3D printing procedure. The pull-out test and tensile test are performed at 5mm/min speed. Stress relaxation testing with 21 cycles is performed with programmed profile: 5 seconds for stretching the specimen up to 1% of strain and keep constant for 10 minutes, then, 1 minute for load removal and keep it at zero stress for 3 minutes for one cycle and repeat 21 times.<br><strong>Results</strong>: The interfacial strength of group-SA (5.71 ± 3.99 MPa), group-S (16.41 ± 2.27 MPa), and group-C (28.83 ± 2.63 MPa) are significantly different (P<0.0001), while no significant difference is observed in the tensile strength between group-SA and group-S (p=0.0570) and between group-S and group-C (p=0.0593). Stress release is greater during the first 10 cycles, reaching a plateau that generally remained constant. Group-SA exhibits the highest initial stress (50.26 ± 1.89 MPa) than other groups and still has 30% residual stress (15.10 ± 1.07 MPa).<br><strong>Conclusions</strong>: Surface-modified metal wire enhances the interfacial bond strength between the wire and resin and static and dynamic mechanical properties of 3D-printed aligners (Figure 1). The innovative integration of clear aligners with metal wire using 3D printing technology demonstrates great potential for complex orthodontic treatment.<br></p>