Doxycycline functionalized polymeric nanoparticles inhibit Enterococcus faecalis biofilm formation on dentine

Abstract

Reinfection and tooth fracture are the most common causes of failure after endodontical treatment. Aim:The purposes of this study were to evaluate the antimicrobial and inhibition of biofilmformation potential of novel remineralizing polymeric nanoparticles (NPs) when applied on the dentinesurface;and to ascertain the effectof the functionalization of these NPs with zinc, calcium or doxycycline.Methodology: The antimicrobial activity and the inhibition of biofilm formation have beenanalyzed on human dentineblocks that were infected with Enterococcus faecalisbefore orafter NPs application. LIVE/DEAD ®testing under the confocal laser scanning microscopy and bacterial culturing were employed to analyse the biofilm biovolume and the bacterial viability. Field Emission Scanning Electron Microscopy was also employed to assess thebiofilm morphology. One-way ANOVA with Welch’s correction and post-hoccomparison by the Games-Howell test were performed for comparisons between groups. Results:The un-functionalizedNPs displayed the highest antimicrobial activity against E. faecalisbiofilms as they provided the lowest biovolume (3,865.7 μm3) and the highest dead/injured cellspercentage (79.93%), followed by Dox-NPs (biovolume:19,041.55μm3, dead/injured cells: 45.53%). Doxycycline loaded NPs showed the highest values of inhibition of biofilm formation with the lowest biofilm biovolume (8,517.65 μm3) and a high dead/injured bacterial percentage (68.68%).Un-functionalizedNPs did not reduce biomass growth, but exerted the highest percentage of compromised cells (93%), being able to disrupt biofilm formation. It also produced occlusion of dentinal tubules, probably interfering with bacterial tubule penetration. Conclusions:Anew generation of bioactive nano-fillers (doxycycline-functionalizedpolymeric NPs) which may be included as primers in endodontic sealers, promoting antibacterial activity and dentinal tubules occlusionis proposed.