Mechanical properties of orthodontic aligners: A review of the literature

Background: The purpose of this study is to identify the mechanical properties of orthodontic aligners and the effect produced by thermoforming and aging in vitro. Material and Methods: A review of the literature was carried out at the end of 2022 in different search engines (PubMed, Scielo, UNAM), using the search strategy: (aligners), (transparent) and (orthodontics) to identify articles that present information on the mechanical properties and the effect of humidity and temperature on orthodontic aligners. Results: Of a total of 17,130 articles found in search engines, only 21 articles met the inclusion and exclusion criteria. For this systematic review, the most frequent criteria were: aligners, mechanical, and thermoplastic. Conclusions: With the review of the literature carried out, it was concluded that aging due to the effect of water absorption and temperature does not affect the thermomechanical properties and the molecular composition as much as the thermoforming process does.