Microbial shifts during dental biofilm re-development in the absence of oral hygiene in periodontal health and disease

Abstract

Aim: To monitor microbial shifts during dental biofilm re-development.

Materials and methods: Supra- and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects at baseline and immediately after tooth cleaning. Samples were taken again from seven teeth in randomly selected quadrants during 1, 2, 4 and 7 days of no oral hygiene. Samples were analysed using checkerboard DNA-DNA hybridization. Species counts were averaged within subjects at each time point. Significant differences in the counts between healthy and periodontitis subjects were determined using the Mann-Whitney test.

Results: The total supra- and subgingival counts were significantly higher in periodontitis on entry and reached or exceeded the baseline values after day 2. Supragingival counts of Veillonella parvula, Fusobacterium nucleatum ss vincentii and Neisseria mucosa increased from 2 to 7 days. Subgingival counts were greater for Actinomyces, green and orange complex species. Significant differences between groups in supragingival counts occurred for 17 of 41 species at entry, 0 at day 7; for subgingival plaque, these values were 39/41 taxa at entry, 17/41 at day 7.

Conclusions: Supragingival plaque re-development was similar in periodontitis and health, but subgingival species recolonization was more marked in periodontitis.

Fig. 1

Mean total DNA probe counts (×10⁵, ± SEM) of supragingival biofilm samples taken at entry (pre-cleaning), immediately post-cleaning and after 1, 2, 4 and 7 days of biofilm development from 38 periodontally healthy subjects and 17 subjects with periodontitis. Total counts from each sample site were averaged in each subject at each time point and then averaged across subjects at each time point separately in each clinical group. Subjects did not perform oral hygiene procedures during the 7 days of the study. Significance of differences between clinical groups at each time point was determined using the Mann Whitney test. Mean total DNA probe counts differed significantly over time in each group (Friedman test, p < 0.001). The bars represent mean total DNA probe counts and the whiskers the SEM at each time point.

Fig. 2

Cumulative mean counts (× 10⁵) of 41 bacterial species in supragingival samples taken from 38 periodontally healthy and 17 subjects with periodontitis prior to professional removal of the dental biofilms, immediately after cleaning, and after 1, 2, 4 and 7 days of re-development. The subjects refrained from oral hygiene procedures for the 7 day test period. Samples were removed from the mesio-buccal aspect of each tooth (excluding third molars) pre-cleaning and immediately post-cleaning. In addition, supragingival samples were obtained from up to 7 teeth in randomly selected quadrants at 1, 2, 4 and 7 days after tooth cleaning. All samples were individually analyzed for their content of 41 taxa using checkerboard DNA-DNA hybridization. Species counts in the samples were averaged within each subject at each time point and then averaged across subjects in the 2 clinical groups. The plots present the cumulative mean values at each time point in each clinical group. The species were ordered and color-coded according to previously described microbial complexes (Socransky et al. 1998).

Fig. 3

Mean counts (×10⁵) of 41 bacterial species in supragingival samples taken from 38 periodontally healthy and 17 subjects with periodontitis prior to professional removal of the dental biofilms, immediately after cleaning, and after 1, 2, 4 and 7 days of biofilm re-development. The subjects refrained from oral hygiene procedures for the 7 day test period. Supragingival biofilm samples were removed from the mesio-buccal aspect of all teeth (excluding third molars) pre-cleaning and immediately post-cleaning. Supragingival samples were also obtained from up to 7 teeth in randomly selected quadrants at 1, 2, 4 and 7 days after tooth cleaning. All samples were individually analyzed for their content of 41 taxa using checkerboard DNA-DNA hybridization. For analysis, species counts in the samples were averaged within each subject at each time point and then averaged across subjects in the 2 clinical groups. Significance of differences in mean species counts between groups at each time point was determined using the Mann Whitney test; * p < 0.05, ** p < 0.01, *** p < 0.001. The species were ordered according to previously described microbial complexes (Socransky et al. 1998).

Fig. 4

Mean total DNA probe counts (×10⁵, ± SEM) of subgingival biofilm samples taken pre-cleaning, immediately post-cleaning and after 1, 2, 4 and 7 days of biofilm development. Computation of counts and data analysis was performed as described in Fig. 1.

Fig. 5

Cumulative mean counts (× 10⁵) of 41 bacterial species in subgingival samples taken from 38 periodontally healthy and 17 subjects with periodontitis prior to professional removal of the dental biofilms, immediately after cleaning, and after 1, 2, 4 and 7 days of re-development. Calculation of species counts and description of the plot were as described in Fig. 2.

Fig. 6

Mean counts (× 10⁵) of 41 bacterial species in subgingival samples taken from 38 periodontally healthy and 17 subjects with periodontitis prior to professional removal of the dental biofilms, immediately after cleaning, and after 1, 2, 4 and 7 days of biofilm re-development. Computation of counts and data analysis was performed as described in Fig. 3.