Nano-sized robots that can transform dental cleaning for root canal procedures

Theranautilus is working to commercialize nano-sized robots that have developed deep clean teeth for root canal procedures. It is a start-up incubated at the Indian Institute of Science (IISc). The company received funding from institutes MeITy, DST (Department of Science and Technology), Nano Mission, Wellcome Trust India Alliance, and DBT (Department of Biotechnology).

These nano-sized robots are controlled using a magnetic field that can help kill the bacteria deep inside dentinal tubules and boost the results of root canal treatments. Root canal treatments are routinely carried out to treat tooth infections in millions of patients.

The dental procedure involves:

• Removing the infected soft tissue inside the tooth is called the pulp.
• Flushing the affected tooth with antibiotics or chemicals to kill the harmful bacteria that caused the infection.

But this treatment often fails to remove all the bacteria – particularly antibiotic-resistant bacteria such as Enterococcus faecalis, that remain hidden inside microscopic canals of the tooth called dentinal tubules.

“The dentinal tubules are tiny, and bacteria reside deep in the tissue, and current techniques are not efficient enough to go inside and kill the bacteria,” Shanmukh Srinivas pointed out. He is the Research Associate at the Centre for Nano Science and Engineering (CeNSE) of the Indian Institute of Science (IISc) and the co-founder of Theranautilus.

In the study regarding the same published in Advanced Healthcare Materials, the researchers designed helical nanobots made of silicon dioxide coated with iron that can be controlled using devices that generate a low-intensity magnetic field. These nanobots were then injected into the extracted tooth samples, and one could track their movement using a microscope.

By tweaking the frequency of this magnetic field, the researchers were thus able to make the nanobots move as they desired and penetrate deep into the dentinal tubules. “We have also established that we can retrieve them … we can pull them back out of the patient’s teeth,” claimed Srinivas.

“We were able to manipulate this magnetic field to make the surface of our nanobots generate heat, which can kill the bacteria nearby. “No other technology in the market can do this right now,” claimed Debayan Dasgupta. He is a research associate at CeNSE and a co-founder of Theranautilus.

The researchers have also tested the dental nanobots in mice models and found them safe and effective. These studies have also proven safe to use in biological tissues. Now efforts are made to develop a new kind of medical device which can easily fit inside the mouth allowing the dentists to inject and control the nanobots inside the teeth during root canal procedures. “Since we are convinced that the dental nanobots are not toxic going by the studies done before, we are in talks with a dental college,” Dasgupta added.

Earlier, ultrasound or laser pulses were being used to create shockwaves in the fluid used for flushing out bacteria and tissue debris to improve the efficiency of root canal treatment. But these pulses penetrated up to a distance of only 800 micrometers. Instead, the nanobots were able to penetrate up to 2,000 micrometers. Using the heat to kill the bacteria also provides a safer alternative to the currently used harsh chemicals or antibiotics, commented the researchers.

Theranautilus was born of several years of work on magnetically-controlled nanoparticles carried out in the lab of Ambarish Ghosh – a Professor at CeNSE. His group, along with collaborators, had previously shown that such nanoparticles could trap and move objects using light, swim through blood, and stick firmly to cancer cells. “We are very close to deploying this technology in a clinical setting, considered futuristic even three years ago.”