Persistent bacterial colonization of Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans in periodontitis and its association with alveolar bone loss after 6 months of therapy

Background, aims: The purpose of this study was to determine whether the pr esence of bacterial antigens for Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), and Actinobacillus actinomycetemcomitans (Aa) in subgingiv al plaque of periodontitis patients after periodontal treatment was associa ted with progressive alveolar bone loss. Method: 39 (39) subjects in good general health previously diagnosed with a dult periodontitis within the last 2 years, and still presenting with probi ng depth >5 mm in 2 to 6 teeth, were studied. All subjects were treated wit h scaling and root planing. Half of the subjects were randomly assigned to receive adjunctive systemic doxycycline (200 mg the Ist day, then 100 mg pe r day for 21 days). Subgingival plaque samples were taken at baseline, 1, 3 and 6 months after therapy. A modified ELISA test (Evalusite(TM), Periodon tal Test Kit, Eastman Kodak Co., Rochester, NY) was used to test for plaque antigens associated with P. gingivalis, P. intermedia and A. actinomycetem comitans. Progressive alveolar bone loss was determined using digital subtr action radiography with standardized radiographs taken at baseline and 6 mo nths after treatment. Results: The presence of P. gingivalis in plaque after treatment was signif icantly associated with progressive bone loss (positive predictive value 84 %, negative predictive value 85%, odds ratio 31.9, p<0.0001). In contrast, the presence of P. intermedia in plaque after treatment was not indicative of progressive loss (positive predictive value 39%, negative predictive val ue 82%). Too few sites had evidence of A. actinomycetemcomitans to be amena ble to statistical analysis. No significant difference in bone loss was att ributable to the systemic antibiotic therapy. Conclusion: These data indicated that, in this population, the presence of P. gingivalis in plaque after treatment might be indicative of progressive alveolar bone loss.