Water sorption, solubility, and relative deformation of thermoplastic materials used for clear aligners: An in vitro study

Lopez-Beraun P.; Liñan-Duran C.; Achachao-Almerco K. · Journal of Clinical and Experimental Dentistry (2026) · DOI: 10.4317/jced.64490

Resumen

Background: Thermoplastic materials used in the fabrication of clear aligners are continuously exposed to the oral environment; therefore, properties such as water sorption, solubility, and dimensional stability may influence their clinical performance. The objective is to compare, through an in vitro study, the physical properties of thermoplastic materials used for the fabrication of orthodontic aligners, under non-thermoformed and thermoformed conditions, after immersion in distilled water. Materials and Methods: A total of 104 specimens obtained from four commercial thermoplastic materials: Claris, Pro Aligner X, Taglus Premium, and Essix ACE® were evaluated under non-thermoformed and thermoformed conditions (n=13 per group). Water sorption and solubility were determined according to ISO 20795–2 after immersion in distilled water at 37°C for seven days. Relative deformation was calculated from changes in thickness before and after immersion. Data were analyzed using one-way ANOVA or the Kruskal-Wallis test, according to data distribution (α=0.05). Results: Significant differences in water sorption were observed among commercial brands in both non-thermoformed (p=0.008) and thermoformed samples (p<0.001). Thermoformed Claris showed the highest water sorption value (22.48 ± 3.20 μg/mm3). Solubility showed no significant differences among materials under any experimental condition (p>0.05). Relative deformation differed significantly among brands in both non-thermoformed and thermoformed samples (p<0.001), with the highest value recorded for thermoformed Claris (1.70 ± 0.79%). Conclusions: The evaluated thermoplastic materials showed different behaviors in water sorption and relative deformation after immersion in distilled water. Thermoformed Claris showed the highest water sorption and relative deformation values, suggesting greater dimensional susceptibility under the evaluated experimental conditions. © (2026), (Medicina Oral S.L.). All rights reserved.

Instituciones: Universidad Peruana Cayetano Heredia