A shape-shifting swarm of tiny robots will soon be able to brush your teeth without a brush!

PHILADELPHIA — A “shapeshifting robotic microswarm” from nanobots could be in your future for flossing and brushing your teeth! Researchers at the University of Pennsylvania say their microscopic dentists “could one day act as a toothbrush, rinse aid and dental floss all in one.”

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

The catalytic reaction causes the nanoparticles to produce antimicrobials that can kill harmful bacteria on a person’s teeth or gums. The team’s experiments showed that the robots can adapt to the shape of a person’s teeth — even if they are crooked — and eliminate any biofilms that cause tooth decay and gum disease.

“Routine oral care is cumbersome and can be challenging for many people, especially those who have trouble brushing their teeth,” said 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 and then rinse your mouth; it is a manual, multi-step process. The big innovation here is that the robotic system can do all three in a single, hands-free, automated way.”

“Nanoparticles can be shaped and controlled in surprising ways with magnetic fields,” added Edward Steager, senior researcher in Penn’s School of Engineering and Applied Science. “We form bristles that can stretch, sweep and even move back and forth across a space, just like flossing. The way it works is similar to how a robotic arm can reach out and clean a surface. The system can be programmed to perform nanoparticle assembly and motion control automatically.”

microswarm dentistry
Arranged in brush-like structures, a robotic microswarm of iron oxide nanoparticles effectively removed plaque. The nanoparticles have both magnetic and catalytic properties; catalyzed hydrogen peroxide produced free radicals that also eliminated tooth decay-causing pathogens. (Image: Minjun Oh/Penn Dental Medicine)

The next generation of dental care is here

“Toothbrush design has remained relatively unchanged for millennia,” explains Koo, adding that even electric toothbrushes still use the brush-on-a-stick template. “It’s a technology that hasn’t been disrupted in decades.”

Interestingly, the team’s robotic breakthrough started as two separate projects. Koo’s group tried to harness the catalytic activity of nanoparticles to release free radicals that would kill tooth decay-causing bacteria. Meanwhile, Steager’s team studied how nanoparticles could serve as building blocks for magnetically controlled microrobots.

Their collaboration married the two ideas and created a platform to electromagnetically control the microrobots and make them change shape to release antimicrobial agents that clean teeth.

In particular, the iron particles self-assemble in the presence of a magnetic field. Then the field can be manipulated to change the shape of the nanoparticle structure to conform to the teeth and gums. As a by-product of the process, the nanoparticles generate free radicals that help eliminate bacteria and pathogens.

“It doesn’t matter if you have straight or misaligned teeth, it adapts to different surfaces,” Koo adds. “The system can adapt to every nook and cranny in the oral cavity.”

Are the robots safe from human mouths?

The researchers note that bristles can become firm enough to clean, but soft enough not to hurt the user! Tests of the bristles on animals showed that they do not damage the gums. Researchers are fine-tuning the system in hopes it could help people in a clinical setting or even at home — especially for older adults and people with disabilities who don’t have the motor skills to brush regularly.

“We have this technology that is as or more effective than brushing and flossing, but does not require manual dexterity,” Koo concludes. “We would like to see this help the geriatric population and people with disabilities. We believe it will disrupt current modalities and significantly improve oral health.”

The study is published in the journal ACS Nano

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