Enterococcus faecalis - a mechanism for its role in endodontic failure

Aim The aim of this study was to identify a possible mechanism that would e xplain how E. faecalis could survive and grow within dentinal tubules and r einfect an obturated root canal. Methodology Cells of Streptococcus gordonii DL1, Streptococcus mutans NG8, or E. faecalis JH2-2 were grown in brain heart infusion broth containing va rious amounts of human serum for 56 days. The ability of the three species to invade dentine and bind to immobilized type 1 collagen in the presence o f human serum was assessed by dentine invasion and microtitre well experime nts. Results All three species remained viable over the period of the experiment when grown in human serum. Cells of all, three bacteria were able to invad e dentine and bind to immobilized collagen. Both of these properties were i nhibited by the presence of collagen in the cell solution. Human serum inhi bited dentine invasion and collagen adhesion by S. gordonii DL1 and S. muta ns NG8, whilst dentine invasion by E. faecalis JH2-2 was reduced in the pre sence of serum, but not inhibited, and binding to collagen was enhanced. Conclusions It is postulated that a virulence factor of E. faecalis in fail ed endodontically treated teeth may be related to the ability of E. faecali s cells to maintain the capability to invade dentinal tubules and adhere to collagen in the presence of human serum.