Microbiological response of localized sites with recurrent periodontitis in maintenance patients treated with tetracycline fibers

Background: Whether adjunctive tetracycline fibers can provide an additive effect to scaling and root planing in treating non-responsive sites in main tenance subjects is still controversial. Recolonization of the bacteria fro m untreated sites or from the extracrevicular region may explain the insign ificant response to local therapy. The purpose of the present study was to evaluate the microbiological response of sites treated with tetracycline fi bers combined with scaling and root planing. Methods: The study was conducted in a spit-mouth design. Thirty patients on maintenance therapy having at least 2 non-adjacent sites in separate quadr ants with probing depths between 4 to 8 mm with bleeding on probing, or asp artate aminotransferase enzyme levels > 800 mu IU in the gingival crevicula r fluid, were treated with scaling and root planing plus tetracycline fiber s or with scaling and root planing only. Subgingival plaque samples were co llected at baseline, and 1, 3, and 6 months following treatment. A. actinom ycetemcomitans, C, rectus, B. forsythus, E. corrodens, E nucleatum, P. ging ivalis, and P. intermedia were detected by culture, immunofluorescence, or PCR technique. Results: There was a reduction of total bacterial cell count, as well as of certain periodontal pathogens, following treatment. The prevalence of A. a ctinomycetemcomitans, B. forsythus, and P. gingivalis and the mean proporti ons of C. rectus, P. intermedia, F. nucleatum, and P. gingivalis decreased after therapy, but there was no statistically significant difference betwee n the 2 treatment groups with respect to bacterial proportions or the numbe r of positive sites. Besides, the pathogens could not be eliminated from th e periodontal pocket, and recolonization of the pocket was noted at 3 month s post-treatment. Conclusions: Bacteria located within the cheek, tongue mucosa, saliva, or u ntreated sites may contribute to reinfection of the pockets and explain the insignificant response to local tetracycline therapy.