Proof of Concept: Shapeshifting Microbots Ability to Brush and Floss Teeth

© Trifonenko Ivan / Adobe Stock (Editor's Note: This stock image is an artist's rendering of general nanobot technology and is not a depiction of the technology in this article.)

Many of our patients find routine dental care burdensome, challenging, and time-consuming. It takes proper technique for oral home care to be efficacious, a technique that not all patients can achieve despite patients’ best efforts and our best efforts with home care instruction. Even with the best technique, tooth morphology, deep grooves, furcation involvement, and crowding, among other factors, can make even the best home care attempt simply inadequate to remove biofilm from all surfaces. Patient dexterity plays an integral role as well.

A multidisciplinary team at the University of Pennsylvania might just be on the verge of disrupting the basic “bristle-on-a-stick” method of toothbrushing and further the mechanical method of interdental cleaning, all while killing pathogenic bacteria.1 This super-smart toothbrush employs a robotics system’s ability to perform these tasks in a single, hands-free, automated manner.

While the idea of a robot brushing and flossing your teeth may sound ridiculous, it’s not as far-fetched as you might think. It could be an effective way to tackle biofilm removal, in turn lowering caries and periodontal disease risks.

How It Began

According to Science Daily, “Research groups in both Penn Dental Medicine and Penn Engineering were interested in iron oxide nanoparticles but for very different reasons.”1 A professor in the Department of Orthodontics and divisions of Community Oral Health and Pediatric Dentistry in Penn’s School of Dental Medicine and co-corresponding author on the study group, Hyun (Michel) Koo “was intrigued by the catalytic activity of the nanoparticles. They can activate hydrogen peroxide to release free radicals that can kill tooth-decay-causing bacteria and degrade dental plaque biofilms. Meanwhile, Steager and engineering colleagues, including Dean Vijay Kumar and Professor Kathleen Stebe, co-director of CiPD, were exploring these nanoparticles as building blocks of magnetically controlled microrobots.”1

“With support from Penn Health Tech and the National Institutes of Health’s National Institute of Dental and Craniofacial Research, the Penn collaborators married the two applications in the current work, constructing a platform to electromagnetically control the microrobots, enabling them to adopt different configurations and release antimicrobials on site to effectively treat and clean teeth.”1

The Study

The researchers aimed to “demonstrate magnetic field-directed assembly of nanoparticles into surface topography-adaptive robotic superstructures (STARS) for precision-guided biofilm removal and diagnostic sampling.”2 These microrobots are composed of iron oxide nanoparticles with catalytic and magnetic properties. Researchers could control their movement and arrangement using a magnetic field to produce bristle-like structures that remove biofilm from the wide surfaces of teeth or elongated threads that can slide between teeth like a piece of floss. In both situations, the nanoparticles are propelled by a catalytic process to release antimicrobials that immediately eliminate pathogens.2

Study Findings

According to tests employing this technique on 3D-printed teeth and real human teeth mounted on a model, the robotic assembly may adjust to various geometries to almost completely eradicate the sticky biofilms that cause dental caries and periodontal disease.1 The Penn team published its findings demonstrating a proof-of-concept for the robotic system in the journal ACS Nano.

Surprisingly, magnetic fields can shape and control nanoparticles in many ways. The bristles, like flossing, can expand, sweep, and even move back and forth across space. It functions like a robotic arm that can reach out and clean a surface. The system can be programmed to do the motion control and nanoparticle assembly automatically.1

The researchers found that the STARS bristles can reach interdental spaces that are confined and hard to reach. “Our STARS bristles can conform to these variations through their adaptive nature. The bristle’s length can reconfigure to reach distant surfaces in confined spaces as it moves from flat to curved and through interdental spaces. We demonstrate this adaptability on a cross-sectional model of human teeth, which enables clear visualization. As bristles are swept over the interdental space, they reconfigure and conform to the curvature of the surface, transforming from a “brush-like shape” to an extended “floss-like structure” that reaches the entire narrow gap. These structures dynamically change their size with a tunable range over multiple length scales; the heights vary from submillimeter to >4.5 mm and widths range from 3 mm to submicrometer, providing structural flexibility to adaptively conform to the interdental region.”2

The researchers further demonstrated a bacterial killing effect. The researchers state, “The data show complete bacterial killing with non-detectable viable cells following treatment with the STARS bristles in the presence of H2O2 on two-dimensional slabs, indicating localized ROS (reactive oxygen species) generation during scrubbing motion for effective bacterial killing. However, the removed biofilm from the control group harbored more than 108 colony-forming units (CFU) mL–1 of viable cells after bristle treatment without H2O2, demonstrating efficacy of the magneto-catalytic bristles for biofilm removal and bacterial killing.”2

In Summary

The researchers foresee this technology being especially helpful for those with dexterity difficulties, including those with debilitating diseases or conditions and the geriatric population.1,2

While this technology is still in its early stages, these researchers seem to have proved the concept that one day, we may see shapeshifting microrobots instead of traditional toothbrushes and interdental cleaners.

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  1. Shapeshifting Microbots Can Brush and Floss Teeth. (2022, July 5). Science Daily.
  2. Oh, M.J., Babeer, A., Liu, Y., et al. Surface Topography-Adaptive Robotic Superstructures for Biofilm Removal and Pathogen Detection on Human Teeth. ACS Nano. 2022; 16(8): 11998-12012.