Supragingival Dental Plaque Research Articles

Ultracytochemical localization of hydrogen peroxide production by dental plaque bacteria

This study looked for evidence of in vitro hydrogen peroxide (HP) synthesis in human dental plaque, using an ultracytochemical technique that included incubation in a CeCl 3-rich medium. Supragingival dental plaque was obtained from periodontally healthy individuals and subgingival dental plaque from human periodontal disease sites. Specificity of the cytochemical reaction was demonstrated using catalase (as HP scavenger). HP production was indicated by an electron-dense precipitate localized at the cell envelope of unidentified Gram-positive and Gram-negative bacteria in both supra- and subgingival samples. The ultracytochemical reaction localized the HP production primarily to the plasma membrane and periplasmic space.

Composition and susceptibility to chlorhexidine of multispecies biofilms of oral bacteria.

Using a constant-depth film fermentor, we have grown a six-membered biofilm community with a bacterial composition similar to that found in supragingival dental plaque. Cryosectioning revealed the distribution of bacteria throughout the biofilm. Exposure to 0.2% chlorhexidine for up to 5 min had little effect on biofilm viability.

An approach to differentiate between antibacterial and antiadhesive effects of mouthrinses in vivo

An experimental set-up allowing differentiation in vivo between antibacterial and antiadhesive properties of mouthrinses is described. The percentage of vital bacteria (=microbial vitality) and the bacterial counts were microscopically evaluated in saliva and in supragingival dental plaque both collected simultaneously at various times during de novo plaque formation. In a cross-over design, 12 healthy participants refrained from all oral hygiene for four separate periods of 2×4 h and 2×72 h after having rinsed with either an amine fluoride/stannous fluoride solution (Meridol®) or 0.9% NaCl (placebo). Stimulated whole saliva was collected before and after the rinse. Together with whole-saliva samples, representative 4, 24 and 72-h-old plaque samples were separately taken from defined vestibular tooth surfaces that had been either exposed to the mouthrinse (unprotected sites) or temporarily covered with inert plastic films (protected sites) during rinsing. The pooled plaque and saliva were stained with fluorescent dyes to differentiate vital from dead micro-organisms which permitted the estimation of the percentages of vital bacteria. The total bacterial counts were quantified under the darkfield microscope. The Wilcoxon test was used for selected pairwise comparisons ( α=0.05). The percentage of vital bacteria in saliva fell significantly from 80–95% to about 50–60% as a result of the antibacterial activity of the test solution. These baseline values and those found in the presence of 4 and 24-h-old plaque were frequently lower than those recorded after the placebo rinse. In comparison to the placebo, microbial vitality was significantly reduced in early supragingival plaque formed on unprotected sites after applying the test solution. The similar total bacterial counts in 4-h-old plaque recorded after the use of the test solution on the unprotected and the protected areas did not point to an antiadhesive effect of the agent. It is concluded that this new experimental set-up allows decoding of the mode of action of a mouthrinse.

Dental Plaque Flora of the Dog with Reference to Fastidious and Anaerobic Bacteria Associated with Bites

Animal bite wounds are amongst the most common types of traumatic injuries in humans. The organisms isolated from these wounds generally reflect the oral flora of the biting animal, and may be fastidious in nature and difficult to identify. This study was undertaken to determine the prevalence of Eikenella corrodens, Actinobacillus actinomycetemcomitans, Porphyromonas and Prevotella spp. in supragingival dental plaque collected from the right maxillary canine and carnassial teeth and the right mandibular canine tooth of dogs. In part one of the study, 30 dogs were used. E. corrodens was found in 62% of these dogs and 44% of individual plaque samples. A. actinomycetemcomitans was not detected in any of the dogs sampled. In part two, 34 dogs were used to determine the prevalence of the black pigmented anaerobic bacilli (Porphyromonas and Prevotella spp.). Porphyromonas gingivalis was present in 68% of these dogs and 47% of individual plaque samples. Prevotella intermedia was present in 44% of the dogs and 23% of individual plaque samples. The recently described Porphyromonas canoris, Porphyromonas salivosa, Porphyromonas cangingivalis, Porphyromonas cansulci, Porphyromonas crevioricanis and Prevotella denticola species were isolated from only 9%, 6%, 3%, 3%, 3% and 3% of dogs respectively. Porphyromonas gingivicanis was not isolated from any of the animals sampled. In conclusion, black-pigmented anaerobic bacilli were isolated from 91% of the animals sampled and therefore constitute a significant risk with respect to bite wound infections. It is also suggested that the prevalence of E. corrodens in wound infections has been underestimated in previous reports because of use of inappropriate techniques for detecting this organism.

Helicobacter pylori in dental plaque and gastric mucosa

Objectives The aim of this study was to investigate the presence of Helicobacter pylori in both dental plaque and gastricmucus. Study design Dental scaling hand instruments were used to collect supragingival and subgingival dental plaque from 81 dentate participants. Denture plaque was obtained from the fitting surfaces of dentures from 41 edentulous patients. Gastric mucus from gastric mucosa of antrum and body of stomach were collected from all 122 participants (92% white) with a soft gastroscopic brush. These samples were dispersed in modified urea broth and normal saline solution before being inoculated onto selective Skirrow's agar and incubated in a microerophilic atmosphere for culturing H. pylori. Results Dental plaque from all dentate participants was negative for H. pylori culture. Only one 80-year-old edentulous patient had positive H. pylori culture in both gastric mucus and denture plaque. Conclusions Although dental plaque has a mixed flora that may act as a reservior for gastric reinfection, dental plaque could not be implicated as the major reservoir of H. pylori for gastric reinfection.

Supragingival dental plaque in the etiology of oral diseases.

Supragingival dental plaque in the etiology of oral diseases.

Microbial vitality of supragingival dental plaque during initial stages of experimental gingivitis in humans.

Although vital plaque micro-organisms are part of the natural ecosystem in the oral cavity they are also the key factor in the development of diseases induced by the human dental plaque. In a previous study (9) the portion of vital bacteria related to the total number of plaque micro-organisms (i.e. the microbial vitality) appeared low in small plaque samples. The objective of this investigation was to determine the exact relationship of microbial vitality and age of supragingival plaque during the early phases of human dental plaque formation. Between intervals of optimal oral hygiene, thirteen participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was completely sampled from a defined area situated on the vestibular surface of the teeth 13, 14, 15, 23, 24 and 25. The pooled plaque from these areas was immediately processed. Total bacterial counts (BC) as enumerated by darkfield microscopy, and colony-forming units (CFU) were recorded. The microbial vitality was calculated indirectly as plating efficiency (PE = CFU per BC) and directly assessed using a vital fluorescence (VF) technique. In the 1 h old plaque samples the median values of PE and VF were 29% and 18%, respectively. Thereafter, the microbial vitality increased significantly with plaque age. The 24 h old plaque samples yielded values of 77% (PE) and 62% (VF). It was concluded that the microbial vitality of the early dental plaque investigated was considerably lower compared to that of a more mature plaque.

Microbial generation time during the early phases of supragingival dental plaque formation.

The objective of this investigation was to determine the microbial generation time during early human supragingival plaque formation. On 2 occasions, 13 participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was sampled from defined areas of the teeth 13, 14, 15, 23, 24 and 25. Two independent methods were used to estimate the total number of viable cells: colony-forming units BCVF, total bacterial counts (BC) as enumerated by microscopic examination, and the percentage of vital bacteria using a vital fluorescence technique (VF) were recorded. The total number of vital microorganisms was calculated by BCVF (= BC x VF). The generation time based on either colony-forming units or BCVF increased significantly with plaque age. During the first interval (1-4 h), the microbial multiplication took slightly less than 1 h. After the establishment of a more mature plaque (24-72 h), the replicating time was between 12.5 h (BCVF) and 14.8 h (colony-forming units). It was concluded that the microbial generation time recorded at the initial stages of plaque formation is considerably lower than that found in older plaque.

The effects of a 0.3% triclosan‐containing dentifrice on the microbial composition of supragingival plaque

144 subjects completed a 6-month, double-blind study which examined the effects of a 0.3% triclosan/2% copolymer/0.243% sodium fluoride dentifrice on the microflora of supragingival dental plaque. The subjects were randomly assigned to use, in an oral hygiene program, either the triclosan/copolymer/fluoride test dentifrice or a control dentifrice. The latter had the same formulation as the test dentifrice except it did not contain triclosan. Supragingival plaque was collected from the buccal and lingual surfaces of 4 teeth at baseline, 3 months, and 6 months, and microbiologically examined by darkfield microscopy, gram stain morphology, immunofluorescence, and selective and non-selective media. Antimicrobial susceptibilities were determined by agar dilution and whole plaque susceptibility methodologies on plaque samples from 136 subjects at each of the above sample periods and at 6-week intervals for an additional 6 months post-therapy. Both dentifrices resulted in highly statistically significant reductions in the total cultivable flora obtained at both the 3 and 6-month samples relative to baseline as well as at 6 months relative to the 3-month sample. The relative decrease in total anaerobic counts and in strict anaerobes, while not statistically significant, was more pronounced at both the 3- and 6-month sample periods in subjects receiving the triclosan dentifrice than for the controls. Neither dentifrice resulted in detrimental shifts in the microbial composition of the normal flora nor led to the emergence of periodontal or opportunistic pathogens.(ABSTRACT TRUNCATED AT 250 WORDS)

Capnocytophaga haemolytica sp. nov. and Capnocytophaga granulosa sp. nov., from Human Dental Plaque

Two new Capnocytophaga species, for which we propose the names Capnocytophaga haemolytica and Capnocytophaga granulosa, were isolated from supragingival dental plaque of adults. The phenotypic characteristics of these organisms were the same as those of the genus Capnocytophaga: gram-negative rods; CO2 requirement; gliding motility; catalase negative; oxidase negative; acids produced from D-glucose, D-maltose, D-mannose, and D-sucrose; and acetate and succinate are the major end products of glucose fermentation. In addition, the cellular fatty acid contents and menaquinones of both species were similar to the cellular fatty acid contents and menaquinones of other Capnocytophaga species. Nevertheless, the levels of DNA-DNA relatedness of the two new species to each other and to other Capnocytophaga species were less than 20%. Two notable characteristics of C. haemolytica are the presence of hemolytic activity and the lack of aminopeptidase activity. C. granulosa has granular inclusions in its cells and grows aerobically. The type strains of C. haemolytica and C. granulosa are A0404 (= JCM 8565) and B0611 (= JCM 8566), respectively.

Microbiology of early supragingival plaque development after delmopinol treatment

The aim of this double blind, cross-over, microbiological study was to compare the effect of topical application of the plaque control agent 0.5% delmopinol HCl with placebo on early supragingival plaque formation. Six subjects underwent 7 periods (0.5, 1, 2, 8 and 24 h and 3 and 7 days) of placebo and delmopinol application, respectively. At the start of each study period the teeth were professionally cleaned and 2 ml of placebo and delmopinol 0.5%, respectively, were applied on all teeth (twice daily for periods lasting 24 h or more). At the end of each period, supragingival plaque samples of one upper and one lower buccal tooth surface were collected separately and cultured on anaerobically incubated Brucella blood agar, on aerobically incubated blood agar and on selective media for the enumeration of Streptococcus spp., Haemophilus spp., Actinomyces spp., Veillonella spp., Neisseria spp. and Fusobacterium spp. The total anaerobic cultivable microflora after delmopinol use was 10-100 times lower than after placebo use. Compared with placebo, the proportion of cultivable aerobes (61.3%), Streptococcus spp. (104.8%) and Haemophilus spp. (82.3%) increased and the proportion of Actinomyces spp. (86.1%), Veillonella spp. (60.5%), Neisseria spp. (96.9%) and Fusobacterium spp. (60.6%) decreased after 7 days. Short-term application of 0.5% delmopinol HCl on supragingival dental plaque regrowth resulted in a reduction of the number of cultivable microorganisms in the plaque and produced a shift in the cultivable plaque composition.

Relationship between bacterial counts, microbial vitality and the accumulation of supragingival dental plaque in humans.

Comparisons between plaque index (PlI) and bacterial counts have been made already; however, these did not take into account the area used for plaque sampling. The objective of the present study was to determine the correlation between the PlI score, the number of bacteria and the bacterial plaque vitality when dental plaque was repeatedly sampled from the same area in each subject during early plaque accumulation. Between intervals of optimal oral hygiene, 10 participants refrained from all oral hygiene measures for periods of 1, 2, 3, 4 and 5 days. The PlI was recorded on the vestibular surface of all first premolars as local PlI:LS. For statistical reasons, the scores of the independent variable LS were added for each subject giving LS* values ranging from 0 to 8. The plaque sampled from this specific surface was circumscribed by the marginal gingiva and an acrylic splint, giving reproducible areas for plaque collection. Total microscopic bacterial counts (BC), colony forming units of anaerobes (CFUan) and aerobes (CFUae), and proportions of vital bacteria (VF) were compared with LS* values. BC and LS* values were strongly correlated. CFUan and CFUae increased significantly with LS*, but this increase was higher for LS* 0 to 4 than for LS* 4 to 8. The ratio between vital and dead microorganisms, assessed by two different methods, was low when an LS* of 0 was recorded, with higher ratios registered for LS* values 4 and 8.

Identification of proteases from periodontopathogenic bacteria as activators of latent human neutrophil and fibroblast-type interstitial collagenases.

Activation of latent human fibroblast-type and neutrophil interstitial procollagenases as well as degradation of native type I collagen by supra- and subgingival dental plaque extracts, an 80-kDa trypsinlike protease from Porphyromas gingivalis (ATCC 33277), a 95-kDa chymotrypsinlike protease from Treponema denticola (ATCC 29522), and selected bacterial species commonly isolated in periodontitis was studied. The bacteria included were Prevotella intermedia (ATCC 25261), Prevotella buccae (ES 57), Prevotella oris (ATCC 33573), Porphyromonas endodontalis (ES 54b), Actinobacillus actinomycetemcomitans (ATCC 295222), Fusobacterium nucleatum (ATCC 10953), Mitsuokella dentalis (DSM 3688), and Streptococcus mitis (ATCC 15909). None of the bacteria activated latent procollagenases; however, both sub- and supragingival dental plaque extracts (neutral salt extraction) and proteases isolated from cell extracts from potentially periodontopathogenic bacteria P. gingivalis and T. denticola were found to activate latent human fibroblast-type and neutrophil interstitial procollagenases. The fibroblast-type interstitial collagenase was more efficiently activated by bacterial proteases than the neutrophil counterpart, which instead preferred nonproteolytic activation by the oxidative agent hypochlorous acid. The proteases were not able to convert collagenase tissue inhibitor of metalloproteinase (TIMP-1) complexes into active form or to change the ability of TIMP-1 to inhibit interstitial collagenase. None of the studied bacteria, proteases from P. gingivalis and T. denticola, or extracts of supra- and subgingival dental plaque showed any significant collagenolytic activity. However, the proteases degraded native and denatured collagen fragments after cleavage by interstitial collagenase and gelatinase. Our results indicate that proteases from periodontopathogenic bacteria can act as direct proteolytic activators of human procollagenases and degrade collagen fragments. Thus, in concert with host enzymes the bacterial proteases may participate in periodontal tissue destruction.

Comparative effects of 2 chemotherapeutic mouthrinses on the development of supragingival dental plaque and gingivitis

Comparative effects of 2 chemotherapeutic mouthrinses on the development of supragingival dental plaque and gingivitis

Comparative effects of 2 chemotherapeutic mouthrinses on the development of supragingival dental plaque and gingivitis

Comparative effects of 2 chemotherapeutic mouthrinses on the development of supragingival dental plaque and gingivitis

Synergistic Degradation of Transferrin by Mutans Streptococci in Association with other Dental Plaque Bacteria

Streptococcus mutans strains Ingbritt and NCTC 10449 and S. sobrinus strains K 1 and SL1 exhibited low, but measurable, ability to degrade human transferrin, a serum-derived glycoprotein. However, when incubated in the presence of other members of the supragingival dental plaque miciroflora, synergistic degradation of transferrin was observed. S. oralis and Fusobacterium nucleatum were most effective, giving rise to levels of degradation up to 3-fold above those observed with either bacterium singly; Actinomyces viscosus gave rise to lower levels of synergy. Combinations of one strain of mutans streptococci with two other strains of dental plaque bacteria gave rise to levels of transferrin degradation which were up to 2–4-fold greater than those of individual bacteria. Supragingival plaque bacteria elaborated a range of complementary glycosidase and peptidase activities which interact in the degradation of glycoproteins resulting in the observed synergistic effects.

Comparative effects of 2 mouthrinses on the development of supragingival dental plaque and gingivitis

A 6-month double-blind, controlled clinical study was completed with 124 healthy adult subjects to determine the efficacy of 2 mouthrinses, Listerine (LA) and Peridex (PX), used as supplements to regular oral hygiene measures in reducing supragingival dental plaque and gingivitis. Following screening examinations for entry levels of existing gingivitis and plaque, baseline gingival and plaque area indices, extrinsic tooth stain, supragingival calculus, bleeding and soft tissue condition were recorded. All subjects then received a complete dental prophylaxis to remove plaque, calculus and extrinsic stain. Subjects were randomly assigned to 1 of 3 groups and performed supervised rinses twice daily for 30 s in addition to their normal oral hygiene, for 6 months. All indices were again evaluated at 3 and 6 months. After 6 months, LA and PX significantly (p less than 0.001) inhibited development of plaque by 36.1% and 50.3%, respectively, and the development of gingivitis by 35.9% and 30.5%, respectively, compared to a hydroalcohol control. PX was more effective in inhibiting plaque and both mouthrinses appeared to be equally effective in inhibiting gingivitis. LA patients did not develop significant levels of stain or supragingival calculus at 6 months, compared to baseline or control. PX patients developed significant levels of extrinsic stain and supragingival calculus compared to baseline and control. Though PX was more effective than LA in the control of plaque, this study indicates that both LA and PX were effective agents in a regimen for the control of plaque and gingivitis.

Adaptive Changes in a Strain ofStreptococcus mutansduring Colonisation of the Human Oral Cavity

When a bacterial strain undergoes a change in environment, its ability to colonise a new niche is optimised over time by the process of natural selection. In this study, a readily identifiable strain of Streptococcus mutans was recovered from supragingival dental plaque of human subjects 3 y after implantation. Fifty fresh isolates were compared to the original laboratory strain that was used to infect these subjects. It was found that the fresh isolates adhered less well than the laboratory strain to saliva-coated hydroxyapatite. The fresh isolates also produced more acetoin and less lactic acid, and had a greater cell yield during aerobic growth in glucose-containing medium. During growth in the presence of sucrose, the fresh isolates produced slightly greater amounts of plaque than the laboratory strain. No differences were observed between fresh and laboratory adapted strains with regard to bacteriocin production, antigenic composition, nutrient requirements, growth rates, or resistance to tetracycline. These results indicate that environmental factors operating in the oral cavity of human subjects select variants of S. mutans that are better adapted to proliferate in vivo . Identification of these factors is important to our general understanding of the ecology of S. mutans and to the development of therapeutic methods. Keywords: Streptococcus mutans ; Adaptation; Implantation.

Adhesion of Non-coccal Dental Plaque Microorganisms to Buccal Epithelial Cells: Inhibition by Saliva and Amphipathic Agents

In the present investigation, the in vitro adhesion of dispersed non-coccal dental plaque bacteria to buccal epithelial cells was examined. Human buccal epithelial cells, incubated in the presence of dispersed supragingival dental plaque, bound averages of ca. 6-15 non-coccal forms/epithelial cell, as opposed to indigenous levels of only 0.2-0.6 on buccal epithelial cells incubated in buffer alone. Adhesion was strongly inhibited by amphipathic agents (Tween 80, sodium dodecyl sulphate, and emulsan), and by saliva. The data suggests firstly that non-coccal bacteria can adhere to epithelial cells in vitro , but may be prevented from doing so in situ by saliva, and secondly that hydrophobic interactions may help mediate the observed adhesion. Keywords: Adhesion; Dental plaque; Epithelial cells; Saliva; Amphipathic agents.

The Role of Surface Free Energy in the EarlyIn vivoFormation of Dental Plaque on Human Enamel and Polymeric Substrata

Strips of teflon and cellulose acetate were glued to the upper lateral incisors of human volunteers in a split mouth, double blind study on the influence of the substratum surface free energy (s.f.e.) on supragingival dental plaque accumulation during a three day period of no oral hygiene. Plaque accumulation, microbial composition of the plaque and s.f.e. of the microorganisms were determined and compared to plaque developed on natural enamel surfaces. Significantly less microorganisms colonised the polymer surfaces (p < 0.002). Streptococcus sanguis I was the predominant microorganism found in enamel samples, comprising about one-third of the total microflora, whereas it was recovered infrequently and in lower numbers from the polymeric surfaces, which predominantly contained Streptococcus sanguis II. Only on cellulose acetate sometimes high numbers of Streptococcus mitis and Streptococcus morbillorum were detected. The mean s.f.e. of the total plaque flora was lowest on teflon (84.5 mJ m -2 ) followed by cellulose acetate (86.0 mJ m -2 ), whereas enamel harboured a microflora with a significantly higher mean s.f.e. (93.0 mJ m -2 ; p<0.05). Also within the same bacterial species lower s.f.e. strains were isolated from the polymer surfaces compared to enamel. The results conform to a previously postulated model in which the interfacial free energy is the driving force for adhesion of microorganisms to solid surfaces. Keywords: Surface free energy; Bioadhesion; Oral microflora; Bacteria; Foreign Bodies.