Gomes, B.P.F.A.*(a), Drucker, D.B.(b) and Lilley, J.D.(b)
(a) Dental School, UNICAMP, Piracicaba, Brazil & *b Turner Dental School, Manchester University, Manchester, UK.

Seventy root canals of patients were originally examined. Of this group, 13 patients subsequently presented with endodontic infection of additional teeth. The aim of this study was to determine whether the microbial flora of the second root canal would correlate with that of the first dental root canal infected. Thus 13 pairs of root canal infections were studied. We collected clinical data, viz. pain, TTP, wet canal, purulent exudate and swelling. Microbiological data were also collected by extensive use of commercial kits to speciate isolates that were cultivable. Associations were sought between data obtained at the first and second attendances and also between clinical features and microbiological features of infection. Statistical analysis used a Pearson X2 test or a one-sided Fisher's Exact test as appropriate. Significant associations were found between a) bacterial species and the presence of Gram-negative bacteria (p=0.03), in particular Prevotella spp. (p=0.01), at both attendances and b) infection of a similar tooth type, whether anterior, posterior, lower or upper, at the first and subsequent attendance (p=0.01).
It is concluded that when two distinct episodes of endodontic infection occur in the same mouth, then similar bacterial species may occur in both cases. Furthermore, a second endodontic infection will tend to affect a similar type of tooth to that initially infected. (Supported by CNPq).