Effect of non-surgical periodontal treatment on clinical parameters and the numbers of Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans at adult periodontitis sites

Background, aims: The purpose of this study was to relate the numbers of Po rphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomyce temcomitans cells to clinical parameters at diseased and healthy periodonta l sites before and after non-surgical periodontal therapy using a sensitive quantitative PCR method (Q-PCR). Method: The sensitivity of the Q-PCR was less than 10 cells for all three s pecies. Subgingival plaque samples R-ere collected from 541 sites in 50 adu lt periodontitis subjects pre-treatment, post-treatment and at a follow-up visit (3-6 months posttreatment). Pocket probing depth, attachment loss and bleeding on probing were recorded at each visit and both healthy and disea sed sites in each subject were sampled. Results: Quantification revealed that P, gingivalis counts were associated with pocket depth (p=0.006) and attachment loss (p=0.010); however, neither P. intermedia nor A. actinomycetemcomitans was associated with the clinica l signs examined, Post-treatment, there was a significant decrease in the n umbers of all three species in both the diseased and healthy sites (86-99%) but none were eradicated. Positive associations were found between any two of the three species studied both pre- and post-therapy By the follow-up v isit, there was a significant improvement in the probing depth of deep site s (p=0.001) but in no other clinical parameters. Conclusion: This study demonstrates the usefulness of Q-PCR for enumerating putative pathogens in clinical periodontal specimens and that the numbers of the three organisms in all sites decrease with non-surgical periodontal therapy.