Clear aligners have revolutionized orthodontic treatment by offering an esthetic and removable alternative to fixed appliances. The recent advent of direct-printed 4D aligners introduces novel smart-material capabilities, particularly ActiveMemory™, which effectively addresses stress relaxation and viscoelastic creep of thermoformed aligners, thereby ensuring more predictable clinical outcomes.
However, one clinical observation that has emerged is the tendency for these aligners to discolor during routine wear. While discoloration is traditionally regarded as a drawback, in 4D aligners it can be reframed as a functional indicator of oral hygiene status, distinguishing them from conventional thermoformed aligners.