Work

Water Desorption Governs Glass Transition Recovery in Aligner Polymers

Year: 2026

Type: article

Abstract: The clinical effectiveness of clear orthodontic aligners mainly depends on the thermomechanical stability of the polymers in this challenging hydrothermal environment. In this study, we compare the water-induced viscoelastic changes and glass transition temperature (Tg) stability of four polymers with different microarchitectures. Specifically, we examined directly printed photopolymer networks (Tera Harz TC-85 and LuxCreo 4D Aligner), a monolithic thermoplastic (Duran+), and a multilayer thermoplastic (ClearCorrect). Samples were immersed in physiological saline (0.9 wt.% NaCl) at 37 °C for 7 days, and Dynamic Mechanical Analysis (DMA) was performed in three conditions: dry, after immersion, and after a 2 h desorption step, mimicking a typical clinical 22:2 wear cycle. All polymers showed a decrease in Tg after immersion, with TC-85 exhibiting the greatest reduction relative to the dry baseline. Tg recovery after a 2 h ambient desorption step was incomplete and was significantly associated with the amount of water retained after 2 h drying (expressed as % of initial uptake; R2 = 0.419), whereas total water absorption after 7 days was not associated with short-term thermal recovery.

Source: Polymers

DOI: 10.3390/polym18081008

Authors: Luka Šimunović, Luka Brenko, Ana Marija Miličević, Tatjana Haramina, Senka Meštrović

Institutions: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture in Zagreb

Language: English

Topic: Dental materials and restorations

Subfield: Orthodontics

Field: Dentistry

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $3,258