Dodecylmethylaminoethyl methacrylate inhibits Enterococcus faecalis in a pH-dependent manner

Area of Science:

• Biomaterials Science
• Microbiology
• Endodontics

Background:

• Enterococcus faecalis (E. faecalis) thrives in acidic environments within root canals.
• Developing effective strategies to combat E. faecalis in root canal sealers is crucial for endodontic treatment success.

Purpose of the Study:

• To investigate the potential of pH-responsive 2-(dimethylamino)ethyl methacrylate (DMAEM) monomers and their copolymers with resin-based root canal sealers to inhibit E. faecalis.
• To evaluate the impact of DMAEM incorporation on the physicochemical and biological properties of root canal sealers.

Main Methods:

• Antibacterial activity of DMAEM monomers was assessed using broth microdilution, crystal violet staining, and qPCR at varying pH levels.
• Resin-based root canal sealers were copolymerized with DMAEM, and their flow, solubility, water sorption, sealing ability, and cytotoxicity were evaluated.
• The efficacy of DMAEM-copolymerized sealers against E. faecalis was determined through direct contact tests, colony-forming unit counts, and live/dead staining.

Main Results:

• DMAEM monomers demonstrated concentration- and pH-dependent inhibition of E. faecalis growth, biofilm formation, and virulence.
• Incorporating 1.25% and 2.5% DMAEM into sealers did not compromise flowability, solubility, or apical sealing but increased water sorption.
• DMAEM copolymers significantly reduced E. faecalis counts and inhibited biofilm formation in a pH-responsive manner, with high cell viability (>90%) at neutral pH.

Conclusions:

• DMAEM monomers and their copolymers exhibit significant antibacterial and antibiofilm effects against E. faecalis, particularly in response to pH changes.
• DMAEM-modified root canal sealers offer a promising approach to inhibit intraradicular E. faecalis in its acidic niche while maintaining biosafety in periapical tissues.