Mechanical properties of thermoformed and 3D-printed aligners after cleansing solution exposure: An in vitro study

The impact of common cleaning solutions on the mechanical properties of clear orthodontic aligners made from PET-G, polyurethane and resin-based materials is of interest. Nanoindentation tests measured elastic modulus, hardness, elastic index and load relaxation after exposure to Retainer Brite®, Fresh Guard® and artificial saliva. The results showed that peroxide-based cleaners significantly degrade aligner properties, while Fresh Guard® causes moderate changes and artificial saliva has minimal effects. Resin-based aligners showed superior chemical stability, making them more resistant to cleaning agents. Thus, mild cleaners are recommended for maintaining aligner performance.