Antibacterial Properties Of Soft-liner Materials Incorporated With Quaternary-ammonium Polyethylenimine Nanoparticles

Objectives: The aim of the present study was to evaluate the antibacterial activity of crosslinked quaternary ammonium polyethylenimine (PEI) nanoparticles incorporated at 1-2% w/w in soft liner materials compared to the non-modified soft liners. Methods: The antibacterial activity was tested against: Enterococcus fecalis, Streptoccocus mutans, Candida albicans, Staphylococcus aureus, Pseudomonas aeruginos and Staphylococcus epidermidis using: (i) the agar diffusion test (ADT); (ii) the direct contact test (DCT); (iii) and bacterial growth in the materials' elute was also tested. Additionally, flexural modulus and flexural strength of the soft liner materials were also tested using a loading machine. Results: DCT results showed antibacterial activity in all three types of soft liner materials incorporating PEI nanoparticles. The effect lasted for at least 1 month. ADT showed no inhibition halo in all tested bacteria, indicating the antibacterial nanoparticles are not diffusing into the agar. Bacterial growth curves for the 1-2%w/w added nanoparticles in the elution test were similar to the appropriate control. Flexural modulus and the flexural strength were not affected at 1%w/w when compared to controls. Conclusion: Quaternary ammonium PEI nanoparticles incorporated in soft liner materials have a strong antibacterial activity without leaching-out and without compromising mechanical properties. Will be presented.