Experimental root canal infections in conventional and germ-free mice.

A small animal model was evaluated to study the interrelationships between microorganisms after their implantation in root canals (inferior central incisors) using germ-free (GF) and conventional (CV) mice. The selected microorganisms were: Porphyromonas endodontalis (ATCC 35406), Eubacterium lentum (ATCC 25559), Peptostreptococcus anaerobius (ATCC 27337), Fusobacterium nucleatum (ATCC 10953), Escherichia coli (ATCC 25922), and Enterococcus faecalis (ATCC 4083). Only P. anaerobius, E. coli, and E. faecalis, respectively, were able to colonize when inoculated alone into the root canal of both CV and GF mice. E. lentum, when inoculated alone colonized only in CV animals. P. endodontalis and F. nucleatum were unable to colonize in CV and GF animals after single inoculation. It is concluded that the experimental animal model presented herein is valuable for ecological studies of root canal infections and that only some strict anaerobic bacteria are able to colonize mice root canals when inoculated by themselves alone in pure culture.