The periodontal status of three groups of women; pregnant, taking oral contraceptives, and nonpregnant, were evaluated clinically and microbiologically for changes in their gingiva and any corresponding changes in the subgingival microbial plaque, specifically the percentage of Fusobacterium species and Bacteroides species. Overall, the women had relatively good gingival health. However, statistically significant increased scores were observed in the Gingival Index and the gingival crevicular fluid flow in the pregnant group compared with the nonpregnant group. The most dramatic microbial changes were the increased proportions of Bacteroides species both in the pregnant group and the group taking oral contraceptives over the nonpregnant group. Increased female sex hormones substituting for the napthaquinone requirement of certain Bacteroides were most likely responsible for this increase. No statistically significant clinical difference was noted between the group taking oral contraceptives and the nonpregnant group, although a 16‐fold increase in Bacteroides species was observed in the group taking oral contraceptives.

ABSTRACT:In the human oral cavity, which is an open growth system, bacteria must first adhere to a surface in order to be able to colonize. Ability to colonize a non-shedding tooth surface is necessary prior to any odontopathic or periodontopathic process. Complex microbe-host relationships occur and must be studied before the commensal-to-pathogenic nature of the human indigenous oral flora can be understood. Medical pathogens, if present in the appropriate host, always produce specific disease. Caries and periodontal diseases are conditional diseases, requiring numbers of certain indigenous species at various sites, particularly the tooth surface. In the case of caries, the condition is related to sugar consumption. Periodontal disease/s may require certain host and environmental conditions, such as local environment or nutritional factors in gingival crevicular fluids. Nonetheless, critical numbers of certain indigenous species must be present in order for these diseases to occur. The aim of this review is to understand the acquisition of the indigenous oral flora and the development of human dental plaque. The role of the salivary pellicle and adherence of indigenous bacteria to it are critical first steps in plaque development. Bacterial interactions with saliva, nutritional factors, growth factors, and microbial physiologic processes are all involved in the overall process of microbial colonization.

A group of streptococci possessing the characteristics of Streptococcus miteor (S. mitis) was found to predominate on nonkeratinized human oral mucosa. These organisms averaged from 76 to 89%C of the total flora cultivable on anaerobically incubated blood agar plates from cheek, lip, and ventral tongue surfaces. They averaged 34, 40, and 18%tof the streptococci in dental plaque, in saliva, and on the tongue dorsum, respectively. Their ability to adhere to oral surfaces was studied by introducing mixtures of streptomycin-resistant strains of S. miteor, S. salivarius, and S. mutans into the mouths of volunteers. Samples of oral surfaces taken 1 hr later indicated S. miteor adhered far better than the other streptococci to buccal mucosa and to teeth, but S. salivarius showed a higher affinity to the tongue dorsum. Glucose-grown cells of S. mutans adhered feebly to all oral surfaces studied and wele rapidly cleared from the mouth. Cells of S. miteor and S. salivarius present naturally in saliva adhered to cleaned teeth comparable to in vitro cultivated strains. Electron microscopy of cells of S. miteor attached to buccal epithelial cells obtained from germfree rats indicated that the organisms possessed a fibrillar "fuzzy" coat which appeared to mediate their attachment to the epithelial cell membrane. This "fuzzy" coat was removed by treatment with trypsin, and it appears to be similar to that previously observed on cells of S. pyogenes and S. salivarius.

This investigation included a cross-sectional component (284, 20-40-year-old subjects/568 sites) and a longitudinal component (19 subjects with moderate to advanced periodontitis/76 sites). Subgingival plaque samples and clinical data were obtained from all upper second bicuspids and first molars in the longitudinal subjects and from both upper first molars in the cross-sectional subjects. The purpose was to: determine/confirm changes in proportions of selected subgingival microorganisms following root planning combined with conventional oral hygiene procedures in the longitudinal subjects, evaluate those changes in terms of an estimate of the naturally occurring distribution of subgingival microorganisms based on data obtained from the cross-sectional subjects and relate shifts in the subgingival microorganisms to changes in clinical measurements. Changes following treatment at sites with pre-instrumentation probing depths greater than or equal to 4.5 mm included cocci, 18.3 to 46.9%; spirochetes, 20.9 to 3.1%; total motile organisms, 28.5 to 5.9%; Fusobacterium spp., 10.2 to 2.2%; and dark-pigmented Bacteroides spp., 14.0 to 9.7%. Translating proportions of microorganisms in samples from subjects in the longitudinal treatment study to equivalent percentile ranks within the large cross-sectional data base demonstrated that at probing depths greater than or equal to 4.5 mm cocci moved from below the 50th percentile in our estimate of the naturally occurring distribution of subgingival microorganisms to above, and spirochetes, total motile organisms and Fusobacterium spp. moved from above the 50th percentile to below. The microbiological findings were consistent with statistically significant improvements in clinical measurements. Statistically significant changes also occurred in microorganisms at sites with initial probing depths less than 4.5 mm.

The distribution of Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus in healthy and diseased adult populations was studied in 3 different ways. First, supragingival plaque formation at 2 through 72 h was examined in 12 periodontally healthy adults using a removable pre-measured surface of enamel bonded to molars and premolars. Second, a cross-sectional examination of the composition of both supragingival and subgingival plaque of unknown age was conducted in 205 adults exhibiting periodontal health to moderate disease. Third, the effects of oral hygiene instruction and root planing on the subgingival microflora of a subset of 19 subjects with moderate periodontitis were examined. The evaluation of 12 adults revealed that the predominant species in early plaque formation (2, 4 and 8 h) was A. odontolyticus. A. viscosus and A. naeslundii were present in developing plaques in almost all subjects in 2-h plaque, but absent in half the subjects when 4-, 8- or 24-h plaque was examined. These two species significantly increased in numbers per mm2 enamel surface area in 48- and 72-h plaques. A. odontolyticus was not related to clinical signs of periodontal disease in 205 adults, and its subgingival proportions in plaque did not change following periodontal treatment of 19 individuals. A. naeslundii was found in significantly higher numbers in supragingival than subgingival plaques in the 205 adults examined. The mean proportion of A. naeslundii significantly decreased as the magnitude of probing depth and attachment loss increased. The proportions of A. naeslundii and A. viscosus were found to be significantly increased in subgingival plaques following periodontal treatment.