The effect of a supragingival plaque-control regimen on the subgingival microbiota in smokers and never-smokers: Evaluation by real-time polymerase chain reaction

Background: The aim of the present study was to evaluate the effect of strict supragingival plaque control on the subgingival microbiota in smokers and never-smokers. Research into the impact of supragingival plaque control on the number of subgingival bacteria has resulted in contradictory findings. Real-time polymerase chain reaction (PCR) has been suggested as a valid alternative to current microbiologic methods based on bacteria cultures. Methods: Forty-five subjects with chronic periodontitis were selected. Twenty-four of them had never smoked, and 21 were active smokers. Four sites per patient were selected for sampling. Supragingival debridement was performed at baseline, and the subjects received weekly instructions on oral hygiene for 180 days. A clinical examination and subgingival plaque sampling were carried out at baseline and at 30, 90, and 180 days. A real-time PCR assay was used to detect and quantify Porphyromonas gingivalis, Parvimonas micra (previously Peptostreptococcus micros or Micromonas micros), Dialister pneumosintes, Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), and the total bacteria load (eubacteria) in the subgingival samples. Statistical analysis was performed using linear models adjusted for the clustering of observations within individuals. Results: Smokers and never-smokers exhibited a similar and significant reduction in total bacteria counts over time. Irrespective of smoking status, deep sites consistently harbored greater quantities of total bacteria throughout the study. Higher numbers of the bacteria investigated were associated with bleeding on probing. Conclusion: Supragingival plaque control markedly reduced subgingival microbiota counts in smokers and never-smokers.