Advancement in micro-robotics may improve endodontic treatments

24 January 2023

Developments in microrobots and nanotechnology could be used in endodontics to access  “difficult-to-reach root canal surfaces, disrupt biofilm, retrieve samples for diagnosis and even deliver drugs”, according to a study from the school of dental medicine at the University of Pennsylvania.

One of the causes of endodontic treatment failure is incomplete root canal disinfection, which can result in periodontitis and infection. This can be due to the difficulties associated with effective biofilm removal.

The University of Pennsylvania researchers tested two different types of micro-robotic platforms, both using iron oxide nanoparticles (IONPs). Prof. Hyun Michel Koo of the Department of Orthodontics at Penn Dental Medicine said to The Dental Tribune, “IONPs are widely used in nanomedicine due to their minimal cytotoxicity, excellent physicochemical properties, stability in aqueous solutions and biocompatibility. Several IONP formulations have already been approved by the US Food and Drug Administration (FDA) for parenteral administration as treatment of iron deficiency anaemia.

“Our previous histopathological analysis of gingival, mucosal and other tissues, including major organs such as the liver and kidney, showed no signs of harmful effects, indicating high histocompatibility of both in-house and FDA-approved IONP formulations.”

The robots were tested on 3D-printed tooth replicas with a biofilm containing four endodontic bacterial species.

Explaining the testing phases, The Dental Tribune stated, “For the first platform, using electromagnets, the research team concentrated the IONPs in micro-swarms and magnetically controlled them to disrupt and retrieve the biofilm. Analysis of the collected sample found all four bacterial species. In addition, under the microscope, all nanoparticles appeared to have been removed from the root canal.

“For the second platform, the research team 3D-printed miniaturised helix-shaped robots and filled them with an IONP-embedded gel. They then guided the robots within the root canal using magnetic fields and observed that they disrupted the biofilm chemically and mechanically with high efficiency. Especially noteworthy is the possibility of loading the helix-shaped robots with therapeutics for targeted drug delivery at the apical region of the root canal, where the infection is in close proximity to the surrounding tissue.”

Reflecting on the findings, Dr Alaa Babeer, the study’s lead author, said, “The key limitations of current endodontic strategies are threefold: lack of precision in targeting biofilms infecting the apical region and anatomical complexities of the root canal, as well as the difficulty of retrieving biofilm samples for diagnosis. To the best of our knowledge, there does not exist an approach capable of simultaneous sample retrieval and antimicrobial treatment in endodontics.

“Our findings demonstrate the feasibility of using the versatility of micro-robotics to access difficult-to-reach endodontic surfaces to perform biofilm killing, removal and retrieval for microbial detection in real-time. Furthermore, we demonstrate the feasibility of robot tracking inside the canal using current clinical imaging modalities.”

Hyun hopes that in the future, micro-robots could be used to deliver drugs or living cells in different oral and craniofacial sites. He believes this could have “diverse applications, including anti-cancer therapy, targeted drug, gene and stem cell delivery, and minimally invasive surgery”.