Dentin Extends the Antibacterial Effect of Endodontic Sealers against Enterococcus faecalis Biofilms

Introduction: The purpose of this study was to evaluate the antimicrobial effects of root canal sealers on Enterococcus faecalis biofilms in dentinal tubules by using a novel dentin infection model. Methods: Cells of E. faecalis were introduced into the dentinal tubules by centrifugation and incubated in brain-heart infusion broth for 3 weeks. An equal thickness of AH Plus, Endosequence BC sealer (BC sealer), and pulp canal sealer EWT (PCEWT) was placed on the root canal wall of the dentin specimens for 1, 7, and 30 days in humid conditions at 37 degrees C. Gutta-percha and water were used in a similar manner as the tested sealers. The proportions of dead and live bacteria inside the dentinal tubules after exposure to root canal sealers were assessed by confocal laser scanning microscopy. Results: Significantly more bacteria were killed in the 3 sealer groups than in the 2 control groups (P < .05). BC sealer and AH Plus resulted in significantly more dead cells than PCEWT did. There was no statistically significant difference between BC sealer and AH Plus at any time point (P > .05). Thirty days of exposure to BC sealer and AH Plus resulted in significantly more dead bacteria in dentin than 7-day and 1-day exposures in the biofilms, whereas no statistically significant increase of the proportion of dead bacteria was detected between 7-day and 30-day PCEWT (P > .05). Conclusions: The 3 endodontic root canal sealers had antibacterial effects against E. faecalis in the dentinal tubules. BC sealer and AH Plus had superior antibacterial effects compared with PCEWT. The antibacterial effects of sealers in dentinal tubules continued after setting.