Bacteriology of Human Experimental Gingivitis: Effect of Plaque Age

Abstract

Twenty-five subjects with previously excellent hygiene and healthy gingiva developed heavy plaque accumulations and bleeding or nonbleeding gingivitis about certain papilla after 21 days of no oral hygiene. Gingival marginal plaque about a single papilla was collected at 0, 1, 2, and 3 weeks of no oral hygiene.in each subject. The plaque was dispersed, serially diluted, and plated on MM10 sucrose agar in an oxygen-free atmosphere. From 50 to 100 colonies from a single high-dilution plate were characterized for each sample. Over 8,500 isolates were partially characterized and placed into one of 29 taxonomic species or groups. The flora was predominantly gram-positive at all time periods. Streptococcal species dominated in the 0-and 1-week-old plaques, i.e. 62 and 43% of the colonyforming units (CFU), but dropped to 26 to 32% of the CFU in the 2-and 3-weekold plaques. Actinomyces species dominated in the older plaques, i.e., 40 to 50% of the CFU. Actinomyces israelii was the most prominent species in the older plaques. Veillonella accounted for 15 to 20% of the CFU at all time periods. Although the other gram-negative species increased with time, collectively they averaged less than 5% of the CFU at week 3. The shift from a Streptococcusdominated plaque to an Actinomyces-dominated plaque was the most striking microbial change observed as the plaque aged.

Changes in subgingival microbiota during puberty A 4-year longitudinal study

“…In agreement to the findings of Delaney et al (1986), the majority of all microorganisms cultivated in the present study were Gram-positive and facultatively anaerobic. These are the or- Chronological Age 689 ganisms which predominate in the microbiota of healthy sites, in gingivitissites in young adults without periodontal disease (Slots 1977, Slots et al 1978, Syed & Loesche 1978 and from normal prepubertal children (Moore et al 1984). Among the Gram-positive bacteria, A. odontolyticus showed a significant time trend of increase.…”

The role of histopathology in the diagnosis and prognosis of periodontal diseases

“…The repeated, renewed insult to the host may have arisen due to a change and/or increase in level of insult from a more aggressive plaque fiora (Slots et al, 1978, Syed & Loesche 1978 and/or from an influx of stimuli due to changes in the epithelium, Saglie et al (1982aSaglie et al ( , 1985 suggest that the event which triggers a burst of activity is invasion of the connective tissue by pocket bacteria, probably following micro-ulceration of the sulcular epithelium (Saglie et al, 1982b), but this view has been questioned by Frank (1988), despite the latter's earlier work showing that bacterial invasion could be found in advanced disease (Frank 1972, Frank & Voegel 1978, Listgarten et al, (1965) have shown clear electron microscopic evidence of connective tissue invasion and colonisation by spirochaetes in acute ulcerative nccrotising gingivitis, an observation confirmed in several other studies (Courtois et al, 1983, Hey-Iings 1967, Listgarten & Socransky 1984, Similarly, Gillett & Johnson (1982) found Gram-negative organisms invading connective tissue in two cases of juvenile periodontitis, an occurrence later confirmed by others (Carranza et al, 1983, Saglie et al, 1982b, Saglie et al 1985, Examination of tissue from two further cases of juvenile periodontitis in the original study failed to reveal bacteria, however, and in none of the patients was there any sign of bacterial proliferation within the tissues. Rather than such invasion being a triggering event, many now believe it to occur at a late stage in the disease process (Frank 1988), Though there is a considerable volume of recent literature regarding bacterial invasion into gingival tissue this does not add significantly to our understanding of the process and its relative importance in disease progression.…”

Microbiological and clinical effects of a dentifrice containing zinc citrate and Triclosan in the human experimental gingivitis model

“…At the completion of the tudy, the test group exhibited over 40% :ewer sites with severe gingivitis. The link between plaque accumulation and gingivitis is well established (Loe et al 1965, Syed & Loesche 1978. However, there is still some debate about whether the onset of gingivitis is simply due to the mass of plaque or the presence of specific pathogens accumulating in the plaque as it ages (Tanner 1988).…”

“…The onset of chronic gingivitis has been correlated with plaque accumulation (Loe et al 1965, Kornman 1986) and an increase in the proportions of Gramnegative anaerobic bacteria (Syed & Loesche 1978). These changes in the oral flora that occur as plaque ages and gingivitis develops have been well documented (Ritz 1967, Syed & Loesche 1978, Moore et al 1982. Their studies have shown that young plaque associated with gingival health contains high numbers of Streptococcal species whereas older plaque, often associated with gingivitis, contains high numbers of Actinomyces species and anaerobic bacteria.…”