The endodontic microflora revisited.

The microbial flora of 35 dental root canals were examined, taking care to maintain the viability of obligate anaerobes which accounted for 45% of total isolations, while streptococcal species accounted for 24% of the total species isolated. Individual root canals yielded a maximum of eight bacterial species. A total of 40 different species was isolated of which the most prevalent were the facultative anaerobe Streptococcus sanguis and the obligate anaerobe, Peptostreptococcus micros (both in 23% of root canals), followed by Eubacterium aerofaciens and the 'Streptococcus milleri group' (both 17%) then Prevotella melaninogenica (formerly Bacteroides melaninogenicus), Enterococcus faecalis and Prevotella oralis (formerly Bacteroides oralis), which were each isolated from 14% of root canals. Highly significant associations were discovered between four pairs of species, viz P. melaninogenica with P. micros, P. melaninogenica with P. oralis, Prevotella corporis with Streptococcus morbillorum and Actinomyces odontolyticus with E. faecalis.