Novel bioactive root canal sealer to inhibit endodontic multispecies biofilms with remineralizing calcium phosphate ions

Objective: The objectives of this study were to: (1) develop a bioactive endodontic sealer via dimethylaminohexadecyl methacrylate (DMAHDM), 2-methacryloyloxyethyl phosphorylcholine (MPC) and nanoparticles of amorphous calcium phosphate (NACP) for the first time; and (2) evaluate inhibition of early-stage and mature multispecies endodontic biofilm, bond strength to root canal dentine, and calcium (Ca) and phosphate (P) ion release. Methods: A series of bioactive endodontic sealers were formulated with DMAHDM, MPC, and NACP. Root dentine bond strength was measured via a push-out test. Three endodontic strains, Enterococcus faecalis, Actinomyces naeslundii, and Fusobacterium nucleatum, were grown on endodontic sealer disks to form multispecies biofilms. Biofilms were grown for 3 days (early) and 14 days (mature). Colony-forming units (CFU), live/dead assay, metabolic activity and polysaccharide were determined. Ca and P ion release from endodontic sealer was measured. Results: Incorporating DMAHDM, MPC and NACP did not decrease the push-out bond strength (p > 0.1). Adding DMAHDM and MPC reduced endodontic biofilm CFU by 3 log. DMAHDM or MPC each greatly decreased the biofilm CFU (p < 0.05). Endodontic sealer with DMAHDM + MPC had much greater killing efficacy than DMAHDM or MPC alone (p < 0.05). Endodontic sealer with DMAHDM + MPC had slightly lower, but not significantly lower, Ca and P ion release compared to that without DMAHDM + MPC (p > 0.1). Conclusions: A novel bioactive endodontic sealer was developed with potent inhibition of multispecies endodontic biofilms, reducing biofilm CFU by 3 log, while containing NACP for remineralization and possessing good bond strength to root canal dentine walls. Clinical significance: The new bioactive endodontic sealer is promising for endodontic applications to eradicate endodontic biofilms and strengthen root structures. The combination of DMAHDM, MPC and NACP may be applicable to other preventive and restoration resins. (C) 2017 Elsevier Ltd. All rights reserved.