Doxycycline functionalized polymeric nanoparticles inhibit Enterococcus faecalis biofilm formation on dentine.

AIM To evaluate the antimicrobial and the potential to inhibit biofilm formation of novel remineralizing polymeric nanoparticles (NPs) when applied to dentine surfaces and to ascertain the effect of the functionalization of these NPs with zinc, calcium or doxycycline. METHODOLOGY The antimicrobial activity and inhibition of biofilm formation of polymeric NPs were analyzed on human dentine blocks that were infected with Enterococcus faecalis before or after application of NPs. LIVE/DEAD ® testing under Confocal Laser Scanning Microscopy and bacterial culturing were employed to analyse biofilm biovolume and bacterial viability. Field Emission Scanning Electron Microscopy was also employed to assess biofilm morphology. One-way ANOVA with Welch's correction and post-hoc comparison by the Games-Howell test were performed for comparisons between groups. RESULTS The un-functionalized NPs displayed the greatest antimicrobial activity against E. faecalis biofilms as they provided the lowest biovolume (3865.7±2926.97 µm3 )(p 0.05), but attained the largest percentage of compromised cells (93±8.23%)(p<0.001), being able to disrupt biofilm formation. It also produced occlusion of dentinal tubules, probably interfering with bacterial tubule penetration. CONCLUSIONS A new generation of bioactive nano-fillers (doxycycline-functionalized polymeric NPs) had antibacterial activity and occluded dentinal tubules. Incorporating these NPs into endodontic sealers may have the potential to enhance the outcome of root canal treatment.