Targeted Radical Delivery for Biofilm Destruction via Electrocatalytic Ceramic Probes

Objectives: In the oral cavity, populations of microbes are responsible for a number of prevalent diseases including periodontitis and pulpitis. Microbes assemble into complex, multi-organism biofilms, increasing their virulence and resistance to removal and treatment. Currently, the most effective way to remove biofilms is through mechanical disruption, although this is not always possible in difficult to access areas such as the dental pulp or in the periodontal space. Here we have adapted technology currently used to remove microbial populations in water systems; by passing low voltages current through titanium electrodes coated with anodically grown TiO₂ microtubules, free oxide radicals can be generated. Before this technology can be adapted for use in the oral cavity, it must be shown that it is both safe for resident cell populations and effective at disrupting mixed oral biofilms.
Methods: Both clonally isolated dental pulp progenitor cells (DPSCs) and mixed salivary biofilms were exposed to free oxide radicals by passing 6V current through titanium electrodes for 0, 15, 100 and 300 seconds. Apoptosis rates in the population of DPSCs were assessed by flow cytometry through the use of an APO-direct labeling kit. Bacterial biofilms were stained with DAPI in order to visualize cell number and distribution.
Results: DPSCs exposed to oxide radicals for less than 300 seconds showed no significant changes in apoptosis rates compared to controls, while exposure to more than 300 seconds resulted in increase in apoptotic cells. Bacterial biofilms that were exposed to 100 and 300 seconds showed a reduction in visible cell number and a reduction in the density of cell distribution, suggesting biofilm disruption.
Conclusions: Titanium electrolytic generated free oxide radicals demonstrated the capacity to disrupt mixed salivary microbial biofilms at exposure levels that did drive DPSC apoptosis, indicating that, with refinement, this technology has potential utility in a number of dental applications.