An army of tiny robots scuttling about inside your mouth cleaning your teeth. It's a disquieting thought, and yet it might be one of the most effective ways to deal with the sticky bacterial biofilms that coat our choppers – as well as water pipes, catheters and other tough-to-clean items.

Run your tongue around your teeth and enjoy the feeling of the biofilms that are pretty much always coating them. Biofilms are little communities of micro-organisms, bacterial and otherwise, that gather together, sticking their cell walls together and bonding themselves to surfaces in three-dimensional structures, scaffolded together with all sorts of claggy polymers. They've been described as little microbe cities, functioning as tiny co-ordinated communities.

They form all over the place – not just in our mouths as dental plaque, but on your dirty dishes, on rocks, in pipes, surgical equipment, anywhere liquid and microbes meet – and when bacteria gang up in these gloopy films, they can become far more resistant to antibiotics than usual.

And they're tough to break – hence why dentists have to spend so much time scraping away at plaque deposits on your teeth in a fiddly and uncomfortable process that's probably about as much fun for the dentist as it is for the patient.

Send in the micro-robots, then! Researchers from the University of Pennsylvania's School of Dental Medicine and School of Engineering and Applied Science have teamed up in an inter-disciplinary study to investigate how tiny plough-like robots can be used to break up biofilms and clean a range of different surfaces.

The uPenn solution uses iron-oxide nanoparticles, and is the result of engineering and dental teams serendipitously bumping into each other and finding out they were working on complementary projects. The engineers had been using iron-oxide nanoparticles to build tiny micro-robots they could control remotely using magnetic fields, and the dental team had figured out that iron-oxide particles can catalyze a reaction that activates hydrogen peroxide, releases free radicals, kills even the most antibiotic-resistant bacteria and breaks up biofilms.

One team had the robotics, then, and the other had a job perfectly suited to that type of robot, so a collaborative study ensued in which this curious combination of engineers and scientists developed what they called Catalytic Antimicrobial Robots, or CARs – little iron-oxide nanoparticles molded into helicoid shapes – and tested how well they worked in biofilm-busting applications.

Timelapse image shows a helicoid-shaped iron-oxide microrobot as it moves through a tooth canal Alaa Babeer, Elizabeth E. Hunter and Hyun Koo

In short, they worked very well. The team suspended their CARs in a solution and steered them around magnetically to precision-clean both flat glass surfaces and enclosed glass tubes. The micro-robots not only degraded and broke up the biofilm, they also dragged the degraded gunk out with them, leaving no trace of biofilm behind.

Emboldened by success, the team moved on to a human tooth, and found that not only were they able to effectively clean the outside surface very effectively, but they could also clean out tough-to-access areas like the isthmus of the tooth – a channel in between root canals that biofilms love, and which is very hard to clean using traditional methods. What's more, when you break these biofilms right down and clear out all their building materials, it makes it substantially harder for new biofilms to begin forming.

"Existing treatments for biofilms are ineffective because they are incapable of simultaneously degrading the protective matrix, killing the embedded bacteria, and physically removing the biodegraded products," says Hyun (Michel) Koo, of uPenn's School of Dental Medicine. "These robots can do all three at once very effectively, leaving no trace of biofilm whatsoever."

Where to from here? In order to get these things into clinical use, the team has begun working with the Penn Center for Health, Devices and Technology, which is designed to help bring new health technologies into clinical applications with business mentorship and resource support. The team also says their system could find applications in reducing the risk of contamination of implants and keeping water pipes and catheters clean.

So it may not be too long before dentists can put away the scraping tools and start deep-cleaning your teeth just by filling your mouth up with liquid and steering a team of CARs around the place magnetically. It'll be a longer-lasting, more effective clean, and if they miss the fun of asking you questions when you've got your mouth held open, I guess they can just ask you while your mouth's full of robot water instead.

The study has been published in Science Robotics.

Source: University of Pennsylvania