Various chemicals and adherence of Enterococcus faecalis to root-canal-dentine substrate

Enterococcus faecalis (Ef) is the most frequently isolated bacteria in root-filled tooth with persistent periapical lesions. Adherence of bacteria to the dentine substrate and its ability to form biofilm has been suggested to be strategies in bacteria to survive harsh environmental conditions. Atomic Force Microscopic investigations have shown that EthyleneDiamine Tetra-acetic Acid (EDTA) when used to remove smear layer during Root Canal Treatment (RCT) would expose an organic layer on the root canal surface. Objective: The aim of this study was to examine the in vitro adherence of Ef to root-canal-dentine and collagen substrates after treatment with chemicals commonly employed in RCT. Materials and Methods: Experiments were conducted in two stages. In stage-1: Dentine sections were prepared and treated with water, EDTA, Sodium hypochlorite (NaOCl) and NaOCl + EDTA. In stage-2: A collagen type-I membrane model derived from pepsinised eggshell membranes were used. Calcium Hydroxide (Ca(OH)₂), Chlorhexidine, EDTA, and Ca(OH)₂+EDTA were used to treat the collagen substrate. All specimens were incubated with Ef for 24 hours and vortexed to remove loosely adherent bacteria. Scanning Electron Microscopy (SEM) and Laser Confocal Scanning Microscopy (LCSM) were used to examine the adherence of Ef on substrates. Results: Both SEM and LCSM showed EDTA treated groups had more bacteria attached to the dentine and Type-I collagen substrate than the other groups. Conclusion: EDTA treated dentine and Type-I collagen substrate displayed greater adherence to Ef.