A new generation of nanobots can kill bacteria in your teeth with heat

Penetrating 2,000 micrometers inside dentinal tubules.
Mert Erdemir
Human tooth with red dots on the blue plexus background.onurdongel/iStock

Teeth are strong, like, really strong. But when problems arise, they can also be very tough and painful. Toothaches, for example, can be total bummers by causing severe pain and sometimes even fever and headache, which make it difficult to maintain the daily routine.

Thankfully, solutions for these very painful dental problems are being developed by scientists. An artificial enamel that's stronger than actual enamel is just one of them. And now, scientists from the Indian Institute of Science (IISc), in collaboration with IISc-incubated startup Theranautilus, have come up with a new tool that can increase the success of root canal treatments.

The team of scientists has developed a set of nano-sized cleaning robots that can clean the hard-to-reach areas deep inside dentinal tubules and kill bacteria via heat. The helically shaped material is made of silicon dioxide coated with iron, which can be controlled using a device that generates a low-intensity magnetic field, according to the official release published by the institute.

A better way to remove the bacteria

One of the problems with the current root canal treatment method is it uses chemicals to kill off the bacteria. However, antibiotic-resistant bacterias, such as Enterococcus faecalis, can resist the attacks and remain hidden inside microscopic canals called dentinal tubules.

“The dentinal tubules are very small, and bacteria reside deep in the tissue," stated Shanmukh Srinivas, a member of the team. "Current techniques are not efficient enough to go all the way inside and kill the bacteria."

Earlier practices like using lasers and ultrasound to wash away the bacteria had their limitations, like being able to penetrate only about 800 micrometers into the tooth. But the new miniaturized robots provide a solution that gives an even deeper cleaning.

The iron coating of the new robots enables them to be controlled by a magnetic field and taken to depths of up to 2,000 micrometers. Being penetrated deep into the dentinal tubules, the tool is tweaked to generate heat and flush out the bacteria.

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Do the nano-sized robots remain inside?

The answer, briefly, is no. It has been established by the team that they can retrieve the nanorobots by drawing them out of the tooth once the operation is done. “No other technology in the market can do this right now,” said team member Debayan Dasgupta. 

The dental nanobots were tested in mice models and proved to be safe and effective. Now, the team is working on a new medical device that can fit inside the mouth and allow the dentist to inject and operate nanobots within the tooth during root canal treatment.

“We are very close to deploying this technology in a clinical setting, which was considered futuristic even three years ago,” says Ambarish Ghosh, a professor at the Centre for Nano Science and Engineering (CeNSE). “It is a joy to see how a simple scientific curiosity is shaping into a medical intervention that can impact millions of people in India alone.”

The results of the research were published in the journal Advanced Healthcare Materials.

Abstract:
Millions of root canal treatments fail worldwide due to remnant bacteria deep in the dentinal tubules located within the dentine tissue of human teeth. The complex and narrow geometry of the tubules renders current techniques relying on passive diffusion of antibacterial agents ineffective. Here, the potential of actively maneuvered nanobots is investigated to disinfect dentinal tubules, which can be incorporated during a standard root canal procedure. It is demonstrated that magnetically driven nanobots can reach the depths of the tubules not possible with current clinical practices. Subtle alterations of the magnetic drive allow both deep implantations of the nanobots isotopically distributed throughout the dentine and spatially controlled recovery from selected regions, further supported by numerical simulations. Finally, the integration of bactericidal therapeutic modality with the nanobots is demonstrated, thereby validating the tremendous potential of nanobots in dentistry and nanomedicine in general.

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