A throng of midget morphing robots may one day brush, rinse, and floss your teeth. Researchers at the University of Pennsylvania created microrobots out of iron oxide nanoparticles that have both catalytic and magnetic activity.
“You have to brush your teeth, then floss your teeth, then rinse your mouth; it’s a manual, multi-step process. The big innovation here is that the robotics system can do all three in a single, hands-free, automated way,”
said Hyun (Michel) Koo, a professor in the orthodontics department and in the University of Pennsylvania’s School of Dental Medicine and co-corresponding author of the study.
Antimicrobials From Catalytic Reaction
Credit: Minjun Oh/Penn Dental Medicine
Using a magnetic field, researchers were able to direct the micro-robots motion and configuration to form either bristle-like structures that sweep away dental plaque from the broad surfaces of teeth or elongated strings that can slip between teeth like a length of floss. In both configurations, a catalytic reaction drives the nanoparticles to produce antimicrobials that kill harmful oral bacteria on site.
Experiments using this system on mock and actual human teeth showed that the robotic assemblies can conform to a variety of shapes to all but eradicate sticky biofilms that lead to cavities and gum disease.
“Nanoparticles can be shaped and controlled with magnetic fields in surprising ways. We form bristles that can extend, sweep, and even transfer back and forth across a space, much like flossing. The way it works is similar to how a robotic arm might reach out and clean a surface. The system can be programmed to do the nanoparticle assembly and motion control automatically,”
says co-corresponding author Edward Steager.
Iron Oxide Nanoparticles
The motions of the microrobots were optimized by the researchers on a small slab of tooth-like material. Next, they tested the microrobots’ performance adjusted for the intricate topography of the tooth surface, interdental surfaces, and the gumline, using 3D-printed tooth models based on scans of human teeth from the dental clinic.
Finally, they trialed the microrobots on real human teeth that were mounted in such a way as to mimic the position of teeth in the oral cavity.
On these different surfaces, the researchers found that the microrobotics system could effectively eliminate biofilms, clearing them of all detectable pathogens. The iron oxide nanoparticles have been FDA approved for other uses, and tests of the bristle formations on an animal model showed that they did not harm the gum tissue.
Fully Programmable Nanoparticle Robots
The system is fully programmable. The team’s roboticists and engineers used variations in the magnetic field to precisely tune the motions of the microrobots as well as control bristle stiffness and length.
The researchers found that the tips of the bristles could be made firm enough to remove biofilms but soft enough to avoid damage to the gums. The customizable nature of the system, the researchers say, could make it gentle enough for clinical use, but also personalized, able to adapt to the particular contours of a patient’s oral cavity.
“We have this technology that’s as or more effective as brushing and flossing your teeth but doesn’t require manual dexterity. We’d love to see this helping the geriatric population and people with disabilities. We believe it will disrupt current modalities and majorly advance oral health care,”
says Koo.
Reference: Min Jun Oh, Alaa Babeer, Yuan Liu, Zhi Ren, Jingyu Wu, David A. Issadore, Kathleen J. Stebe, Daeyeon Lee, Edward Steager, and Hyun Koo.Surface Topography-Adaptive Robotic Superstructures for Biofilm Removal and Pathogen Detection on Human Teeth. ACS Nano 2022, 0.1021/acsnano.2c01950
