The army of transforming robots helps clean teeth

The micro-robot system made from iron oxide particles can change shape according to tooth shape, cleaning teeth more effectively.

Engineers at the University of Pennsylvania have developed a system of tiny robots that can change shape to form stiff hairs or floss. They not only help clean up plaque but also secrete antibacterial substances to kill harmful bacteria. The new study was published in the journal ACS Nano on June 28.

Brushing and flossing every day can be annoying. People who do this regularly can still miss some places in the mouth. One reason is that toothbrushes can't adjust to individual differences in tooth shape or spacing.

The new robotic system solves this problem by "transforming". The robot consists of iron oxide nanoparticles, which can be assembled into different shapes and controlled by magnetic fields. As a result, the particles can be arranged into a brush-like shape to brush away plaque from the surface of the teeth, or smaller fibers like dental floss to squeeze between teeth.

The army of microscopic robots doesn't just clean teeth mechanically. Iron oxide can activate hydrogen peroxide, which leads to a reaction that produces free radicals that destroy bacteria and the sticky biofilm they leave on teeth.

Scientists test a micro-robot tooth brushing system.

The team first tested the new system on a flat plate of artificial tooth-like material to track the movements of the robots. They then moved on to control them on a 3D printed tooth model. Finally, the tiny robots are tested on real human teeth mounted in a specialized device with a mouth-like arrangement.

Tests show that the robotic system can effectively remove plaque and biofilm, reducing the amount of pathogenic bacteria below detectable levels. The team was also able to precisely control the stiffness and length of the bristles by adjusting the magnetic field, making the bristles stiff enough to clean teeth but still soft enough to not cause gum damage.

The tiny robotic system's customizability makes cleaning people's teeth more efficient, the team says. Besides, because there is no need to use hands, the system will allow people with reduced motor skills to still take care of their oral health.