Using a magnetic field, researchers say they can direct the microrobots' motion and configuration to form either bristle-like structures like a toothbrush, or elongated strings that can slip between teeth like dental floss. In either case, the building blocks of these tiny robots contain iron oxide nanoparticles, which produce both catalytic and magnetic reactions.

The catalytic reaction drives the nanoparticles to produce antimicrobials that can kill harmful bacteria on a person's teeth or gums. The team's experiments demonstrated that the robots could conform to the shape of a person's teeth — even if they're crooked — and eliminate all of the biofilms that cause tooth decay and gum disease.

"Routine oral care is cumbersome and can pose challenges for many people, especially those who have hard time cleaning their teeth" says Hyun (Michel) Koo, a professor in the Department of Orthodontics and divisions of Community Oral Health and Pediatric Dentistry in Penn's School of Dental Medicine, in a university release. "You have to brush your teeth, then floss your teeth, then rinse your mouth; it's a manual, multistep process. The big innovation here is that the robotics system can do all three in a single, hands-free, automated way."