Characterization of a Novel Antimicrobial Agent for Endodontic Applications*

Recurrent endodontic infections are primarily caused by persistent bacteria Enterococcus faecalis and are more challenging to treat, compared to primary infection of the root canal system. Current treatment, calcium hydroxide (CaOH), is used despite its inefficacy against E faecalis and other common endodontic pathogens, so we developed a more effective composite material named “CASA”. This study characterizes the antimicrobial properties, cytotoxicity, and differentiation potential of CASA for dental pulp stem cells (DPSCs). To determine antimicrobial properties, agar plates were inoculated with common endodontic pathogens. Then, CASA or CaOH was inserted into wells in the agar plate with a diameter of 6 mm. They were incubated for 24 hrs, and then zones of inhibition were measured. CASA produced larger zones of inhibition than CaOH for all species tested. Cytotoxicity studies indicated a high tolerance for DPSCs for CASA, with a measured IC50 of 1.0 mg/ml, a far higher dose than tissue would be exposed to during standard treatment. Addition of 0.25 mg/ml of CASA to DPSCs in osteogenic culture, in the absence of dexamethasone, was observed to hinder differentiation and preserve stemness of the culture.