Thermo-mechanical properties of 3D printed photocurable shape memory resin for clear aligners

Abstract

To overcome the limitations of the conventional vacuum thermoforming manufacturing method, direct 3D printing of clear aligners has been developed. 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, comparing to a conventional thermoplastic material polyethylene 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 the shape memory properties provide advantages for the clinical application.

Three-Dimensional-Printed Customized Orthodontic and Pedodontic Appliances: A Critical Review of a New Era for Treatment

“…Three articles focused on the 3D printing fabrication of appliances that included bands. One introduced 3D printing of orthodontic brackets, and three looked at direct-printed clear aligners [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…In addition, the expected force decay induced by repeated insertion of the clear aligners is reduced and a constant orthodontic force can be maintained. Furthermore, its geometric stability at high temperatures and its shape memory properties provide advantages for clinical application [ 13 , 14 , 15 ] ( Figure 8 ). Printed aligner manufacturing follows a specific protocol that should be accurately followed.…”

Advances in orthodontic clear aligner materials

“…Currently, the first fabrication process is widely adopted both commercially and clinically, including for the in-house production of aligners [ 51 ]. While, for the direct 3D printing process, with the exception of Tera Harz TC-85 (Graphy, Seoul, South Korea), which has been approved by the Korea Food and Drug Administration (KFDA), European Commission (EC) and Food and Drug Administration (FDA) as per the company website [ 52 ], there is no other 3D printable material currently available commercially that meets the standard of biocompatibility, translucency, and appropriate mechanical properties [ 39 , 40 , 42 ].…”

“…Fig. 4 illustrates a relative comparison of the stress-strain curves of different orthodontic materials [ 52 , 81 , 85 , 86 ].

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Effectiveness and Efficacy of Thermoformed and 3D Printed Aligners in Correcting Malocclusion (Spacing) and Its Impact on Periodontal Oral Health and Oral Microbiome: A Double-Blinded Parallel Randomized Controlled Multicenter Clinical Trial

“…Recently, clear aligners have been introduced for correcting intrusion, extrusion, spacing, buccolingual angulation, anterior buccal and palatal angulation, etc. [ 5 , 6 , 7 , 8 ]. There are different commercially thermoplastic materials to produce the clear aligners on dental models that express the tooth movement [ 9 , 10 , 11 , 12 ].…”