Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans

The antibacterial activity of quaternary ammonium polyethylenimine (PEI) nanoparticles embedded at 1% w/w with clinically used bonding, flowable and hybrid dental composite resins and cured by light polymerization was studied. The antibacterial activity was tested with Streptoccocus mutans by: (i) the agar diffusion test (ADT); (ii) the direct contact test; (iii) bacterial growth in the materials elute; (iv) and scanning electron microscope (SEM). Using the direct contact test, antibacterial activity ( p