Drug-Silica Co-Assembled Particles Improve Antimicrobial Properties of Endodontic Sealers.

Abstract Objectives Assess the antimicrobial activity and flow of root canal sealers after incorporating novel highly-loaded antimicrobial drug-silica co-assembled particles (DSPs). Methods DSPs were synthesized through co-assembly of silica and octenidine dihydrochloride (OCT) antimicrobial surfactant. DSPs were loaded (1 and 2% wt.) into epoxy resin sealer (AH Plus®, Dentsply (AH)) or calcium silicate-based sealer (BC SealerTM, EndoSequence (BC)). OCT release from DSP-modified sealers was determined using liquid chromatography. Antimicrobial activity of sealers against planktonic or biofilm form E. faecalis was assessed using direct contact and membrane restricted tests. Sealer flow was tested according to ISO6876, 2012. Results OCT release from BC+1% or 2% DSPs was above the minimum inhibitory concentration (MIC) following 2 days throughout the 30 days experiment, while OCT release from AH+1% or 2% DSP was significantly below the MIC against Enterococcus faecalis (4 μg/mL) over the whole 30-day experimental period. All materials (with or without DSPs) killed planktonic bacteria initially. AH±1% or 2% DSPs had no antimicrobial activity after 7 days. BC+1% or 2% DSPs maintained antibacterial activity over the 30-day period. Both modified and unmodified sealers completely inhibited the growth of E. faecalis biofilms after 24 hr. of contact. DSPs decreased the flow of AH and BC sealers; for AH the reduction was proportional to the amount of DSPs added. All modified and unmodified sealers except for AH+2% DSPs were within the acceptable limits of ISO6876 flow tests. Conclusions DSPs enhanced the antimicrobial performance of BC but not AH sealer while the material’s flow remained compliant with ISO6876 standards. Depending on the sealer, DSPs may enhance antimicrobial efficacy in root canal treatment and potentially improve treatment outcome.