Microbial flora in the acute phase of periodontitis and the effect of local administration of minocycline.

Periodontitis, similar to other infectious diseases, is known to progress as chronic inflammation with recurrent acute phases. The purpose of this study was to clarify the microbiological composition of the acute phase and to compare the bacterial flora with that of comparable chronic periodontal pockets. We also evaluated the effect of application of minocycline gel locally on the change in the microflora in the acute pockets. Microbial flora from the subgingival pockets of 28 patients in the acute phase of periodontitis and of 12 patients in a comparable chronic phase as the control were investigated by various bacterial culture methods including TS blood agar and TSBV plates. Minocycline gel was applied to the acute periodontal pockets. Changes in the microbiological proportion and clinical parameters at one week after baseline examination were followed by dark-field analysis, culture method, and indirect immunofluorescence technique. Characteristic features of bacterial proportions in the acute site were observed as an increase in Bacteroides forsythus. The number of Porphyromonas gingivalis and black pigmented anaerobic rods also increased. Application of minocycline gel in the acute pocket without any debridement produced improvement in clinical symptoms at one week. Black-pigmented anaerobic rods, P. gingivalis, and B. forsythus decreased significantly at one week after the application. Results indicate that periodontopathic bacteria including B. forsythus and P. gingivalis were predominant in the acute phase of periodontitis and a locally delivered antibiotic may be effective as an alternative modality of treating the acute inflammation.