Supragingival and subgingival microbiota of adult patients with Down's syndrome. Changes after periodontal treatment

In this longitudinal study, five adult Down's syndrome patients with periodontitis were placed on a frequent recall visit schedule (every 6 weeks) after treatment, in order to investigate: 1) the microbiological status, both supragingivally and subgingivally, and the changes that occurred after treatment and 2) the effect of frequent professional supragingival plaque control on the subgingival microbiota and clinical variables in these patients. The clinical variables recorded were probing pocket depth, probing attachment level, bleeding on probing and presence of plaque (full mouth, six surfaces per tooth). Microbiological examination was performed separately for supragingival and subgingival samples from the same site for 14 species, using whole genomic DNA probes and the "checkerboard" DNA-DNA hybridization technique. The findings indicate that, although a reduction of periodontal indices was noticed, plaque levels remained high (60%) even at the end of the experimental period. Periodontal pathogens including Porphyromonas gingivalis, Bacteroides forsythus and Actinobacillus actinomycetemcomitans were frequently detected both supragingivally and subgingivally (>30%). The presence of a species supragingivally and the presence at the same time points subgingivally were correlated. This finding suggested that supragingival plaque acts as a reservoir for reinfection of treated sites. A reduction of the percentages of detection of these species was noticed 1 month after an oral hygiene period as well as at 3 and 6 months after treatment. Inadequate oral hygiene as performed by these patients probably affected supragingival, and consequently subgingival, plaque composition.