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A three-year prospective study of adult subjects with gingivitis II: microbiological parameters.

AIM
To investigate whether the clinical benefits obtained with a periodontal prevention programme in subjects with periodontal health or minimal disease were accompanied by beneficial changes in the subgingival microbiota.


MATERIAL AND METHODS
One hundred and twenty-four subjects completed the study. Subjects were clinically and microbiologically monitored at baseline, 1, 2 and 3 years. Subgingival plaque samples were taken from the mesiobuccal aspect of every tooth and were analysed for the levels of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples=13,477). The mean counts of each of the 40 test species were calculated for each subject at each time point. Significance of differences over time was sought using the Friedman test. p values were adjusted for multiple comparisons.


RESULTS
All clinical parameters, at the microbiologically sampled sites, improved over time. The clinical changes were accompanied by statistically significant decreases in the mean counts of 35 of the 40 test species. Major reductions occurred by year 2 for Actinomyces, Capnocytophaga, Campylobacter, Fusobacterium and Prevotella species. At year 3, there was a modest re-growth of the majority of the species.


CONCLUSIONS
The clinical improvements obtained through preventive measures were accompanied by a shift to a more host-compatible subgingival microbiota.