Effect of thermomechanical aging on force system of orthodontic aligners made of different thermoformed materials

• DOI: 10.1007/s00056-024-00527-0
• Publication Date: 2024-04-23T17:02:24Z
• Authors: Tarek M. Elshazly; Ludger Keilig; Diva Nang; Bijan Golkhani; Anna Weber; Hanaa Elattar; Sameh Talaat; Christoph Bourauel
• Keywords: Thermoforming

Abstract Purpose The aim was to investigate the effect of aging by thermocycling and mechanical loading on forces moments generated orthodontic clear aligners made from different thermoplastic materials. Methods A total 25 thermoformed 5 materials, i.e., Essix ACE® Essix® PLUS™ (Dentsply Sirona, Bensheim, Germany), Invisalign® (Align Technology, San Jose, CA, USA), Duran®+ (Iserlohn, Zendura™ (Fremont, underwent a 14-day protocol involving (a 0.2 mm vestibular malalignment upper left second premolar [tooth 25]) in deionized water (temperature range 5–55 °C). 3D forces/moments exerted tooth resin model were measured at three time points: before (day 0), after 2 days 14 aging. Results Before aging, extrusion–intrusion 0.6–3.0 N, orovestibular 1.7–2.3 as mesiodistal rotation 0.3–42.1 Nmm. In all directions, multilayer exhibited lowest force/moment magnitudes. After materials showed significant decay within first days, except for vertical translation. However, following thermomechanical had equivalent or even higher (direction load). Conclusion Thermomechanical significantly reduced during 48 h. Multilayer aligner exhibit lower initial than single-layer ones, less influenced Material hardening observed subjecting some loading. Thus, orthodontists should be aware possible deterioration over time. This work also sheds light how material selection impacts behavior may provide valuable guidance regarding optimal timing changing protocol.