A team of researchers at the University of Pennsylvania have developed a shapeshifting nanotechnology that can be used to clean teeth and gums without the use of hands. The proof-of-concept device uses iron oxide nanoparticles that can self-assemble in the mouth. They change their form and function based on magnetic fields and catalytic reactions. The device is capable of brushing teeth in a bristle-like form and flossing gums when elongated, with settings that can be customized from person to person.