Periodontal bacterial species in hopeless dentitions with severe periodontitis: comparison of levels before extraction and 90 days after immediate implant placement

The aim of this study was to evaluate changes in periodontal bacterial species during the transition from hopeless teeth to denture-supporting immediate implants. Biofilm and saliva samples were collected from 13 women and 7 men before the extraction of hopeless teeth with severe periodontitis (baseline) and 90 days after the placement of immediate implants that supported immediately loaded complete dentures (day 90). The levels of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Streptococcus oralis were analyzed by real-time polymerase chain reaction. Differences in the levels of bacterial species in the subgingival biofilm and saliva and between baseline and day 90 were evaluated by a 2-way analysis of variance followed by the Tukey test. There was a significant reduction in the levels of T forsythia from baseline to day 90 in saliva and subgingival biofilms (P < 0.05) and a tendency toward a reduction of the other bacterial species. The total bacterial load was higher in saliva than in subgingival biofilm at baseline and day 90 (P < 0.05), while the individual levels of all species were higher in the biofilm than in saliva at both times (P < 0.05). The results showed an overall reduction in the levels of pathogenic bacterial species, particularly T forsythia, during the transition from hopeless dentition to implant-supported dentures. The subgingival biofilm harbored considerable levels of pathogenic species, suggesting that implant placement immediately after extraction of teeth with severe periodontitis may induce changes that favor colonization by pathogenic microorganisms.