TC-85, new material for direct 3D printed clear aligners exhibits significant benefits

A study was conducted to overcome the limitations of the conventional vacuum thermoforming manufacturing method, and direct 3D printing of clear aligners has been developed.

Clear aligners have been investigated since Kesling first introduced a tooth positioner fabricated with an elastic polymer in 1945, to move the teeth without bands, brackets, or wires, while Nahoum reported a 'vacuum-formed dental contour appliance' in 19642. Align Technology Inc. (Santa Clara, CA, USA) has collated several concepts across literature and applied computer-aided design (CAD)/computer-aided manufacturing (CAM) technology to the manufacturing process of clear aligners. As a result, the efficiency of manufacturing clear aligners has increased and expanded their range of applications. Accordingly, several efforts have been made to develop advanced materials that are suitable for the CAD/CAM technology.

The present study investigated the thermo-mechanical and viscoelastic properties of a photocurable resin TC-85, which is a new material for the direct 3D printed clear aligners, compared to a conventional thermoplastic material polyethene terephthalate glycol. Dynamic mechanical analysis was performed to analyse the mechanical behaviours of the two materials at 37 °C and 80 °C, respectively. Furthermore, the shape memory property of the two materials was evaluated using a U-shape bending test, and the shape recovery ratio for 60 min at 37 °C was calculated. The results indicate that TC-85 can constantly apply a light force to the teeth when used for the 3D printed clear aligners, owing to its flexibility and viscoelastic properties.

In addition, it is expected that the force decay induced by repeated insertion of the clear aligners will be reduced and a constant orthodontic force will be maintained. Furthermore, its geometric stability at high temperatures and shape memory properties provide advantages for clinical application.

Therefore, TC-85 presents favourable properties and demonstrates significant advantages for the clinical application of aligners.

Reference:

Thermo-mechanical properties of 3D printed photocurable shape-memory resin for clear aligners by Se Yeon Lee, et al. published in the Scientific Reports.

https://doi.org/10.1038/s41598-022-09831-4