POSITIVE AND NEGATIVE ASSOCIATIONS BETWEEN BACTERIAL SPECIES IN DENTAL ROOT CANALS

Significant associations have been previously reported between certain pairs of bacterial species isolated from human dental root canals. Th e aim of this study was to examine microbiologically a more extensive series of cases, with particular reference to obligate anaerobes which accounted for 64% of total isolations. A total of 65 different specie s was isolated and individual root canals yielded a maximum of eleven bacterial species. Highly significant positive associations (p <0.001) were found between Peptostreptococcus spp. and Prevotella spp., betwe en Peptostreptococcus spp. and P. melaninogenica, between P. micros an d Prevotella spp., P. micros and P. melaninogenica and between Prevote lla spp. and Eubacterium spp., all with an ODDS ratio of >9.0. In cont rast, negative and highly significant associations (p <0.01) were foun d only between the four species pairs: B. vulgatus/F. necrophorum, P. magnus/Bifidobacterium spp., B. gracilis/F. nucleatum and between B. g racilis/Fusobacterium spp.; all with an ODDS ratio of <0.5. Some previ ously published associations were confirmed and some new associations were found, while some negative associations became apparent.