Microbial Shifts in Early Supragingival Biofilm Formation

Objectives: To compare early microbial changes in supragingival biofilm formation in periodontally healthy, periodontitis and edentulous subjects. Methods: Supragingival plaque samples were taken from the mesial aspect of each tooth in 30 periodontally healthy, 8 periodontitis and 18 denture-wearing subjects, at entry, and individually analyzed for their content of 41 bacterial species using checkerboard DNA-DNA hybridization. The teeth (or denture) were cleaned and immediately re-sampled. Subjects refrained from oral hygiene for 7 days. Plaque samples were taken from 7 teeth in randomly selected quadrants at 1, 2, 4 and 7 days and analyzed as described above. Counts of each species were determined for each sampled site and averaged in each subject at each time point. Significance of difference for each species over time was determined by the Friedman test and between clinical groups at each time point using the Kruskal-Wallis test. Results: Mean (x10⁵, ±SEM) total DNA probe counts were 45.1±6.6, 65.8±12.0 and 52.2±10.6 on entry and 5.5±1.0, 8.5±3.8 and 5.8±0.9 immediately post-cleaning in healthy, periodontitis and edentulous subjects respectively. Total counts in healthy and periodontitis subjects exceeded baseline values (60.7±10.8, 63.8±12.7) at 2 days, but took 4 days in edentulous subjects (57.2±18.3. Baseline mean counts of most species were highest in periodontitis and lowest in edentulous subjects. Counts of streptococci, A. actinomycetemcomitans, P. micros, E. corrodens, V. parvula returned to baseline levels by 2 days. Remaining species returned to baseline levels by 4-7 days. Streptococci plateaued between 2-7 days. The pattern of supragingival re-colonization in periodontitis and health was virtually identical and more rapid than in edentulous subjects. Conclusions: Supragingival plaque re-development occurs at a similar rate in periodontitis and health and faster than on dentures. Species differ in their rate and maximum level of re-colonization achieved during 7 days of no home care. Supported by NIDCR grant DE14368.