US Patent 11766314 Methods for making multilayer dental aligners

A multilayer sheet comprising first and second layers is provided. The first layer consists of a co-polyester. The second layer consists of a thermoplastic polyurethane elastomer having an elongation at break of greater than 200%, a hardness of 60A to 85D, an ultimate tensile strength of greater than about 5000 psi, and a light transmission between 400 nm and 800 nm of greater than about 75%. A mold is provided and the multilayer sheet is thermoformed over the mold to form a plurality of tooth-receiving cavities configured to receive and reposition a patient's teeth from a first arrangement toward a second arrangement. Excess material is trimmed from the thermoformed multilayer sheet to form a multilayer dental aligner.