Introduction: The aim of this study was to investigate the anti-biofilm effect of silver citrate nanoparticles, Doxycycline, and a mixture of sodium hypochlorite-Etidronic acid on extra-radicular biofilm on the most apical part of the root of extracted teeth with persistent apical periodontitis. Methods: The apical 2mm of the distal root of thirty freshly extracted mandibular teeth with persistent apical periodontitis was resected, the presence of mature extraradicular biofilm was confirmed with CLSM then samples were treated for 5 minutes with an antimicrobial solution according to their random distribution into three groups. Group I: Silver citrate nanoparticles, Group II: Doxycycline, and Group III: Mixture of 1% NaOCl with Etidronic acid (HEBP), then samples were scanned with CLSM to detect live/dead bacteria in the bacterial biofilm Results: There was no statistically significant difference between mean percentages of dead bacteria in the three groups (P-value = 0.597), experimental root end sections showed statistically significantly lower mean percentage of live bacteria than control root end sections (P-value <0.001). Conclusions: The applied antimicrobial solutions in the diluted concentration and limited time of application failed to eradicate the mature extraradicular biofilm, therefore further investigations are needed to conclude a biocompatible chemical or mechanical method to be used during periradicular surgery for elimination of extra-radicular biofilm.
Clinical implications: Extra-radicular biofilm was present on the majority of the collected samples with persistent apical periodontitis; therefore, disinfection of the root end surface is a must when resection of the whole infected apical part of the root is not feasible.