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Background: Epidemiological studies have shown a link between periodontitis and atherosclerosis. Hence the present study was chosen to assess the presence of eight anaerobic periodontal pathogens and their virulence genes in subgingival plaque (SGP) and atheromatous plaque (AP) of patients with Ischaemic heart disease., Methods: SGP and AP collected from 65 Ischaemic heart disease patients were screened for the presence of periodontal bacterial pathogens by Polymerase chain reaction. The samples positive for Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia were screened for virulence genes. Chronic periodontitis patients (ChP) without any systemic disease (n = 59) and healthy subjects free of both periodontitis and systemic disease were included as control groups (n = 100)., Results and Discussion: Statistical significance was observed for the prevalence of 16S rRNA of P. gingivalis, T. forsythia, T. denticola and P. nigrescens both in SGP and AP. Nine different periodontal bacterial co-occurrences were observed in SGP and AP of Ischaemic heart disease patients. Besides, the prevalence of these nine different bacterial co-occurrence was high in SGP OF Ischaemic heart disease patients compared to ChP without systemic disease. Among the nine different bacterial co-occurrence, only four were observed in SGP of ChP without systemic disease in spite of high prevalence of these anaerobic bacterial species. While, bacterial co-occurrences was completely absent among healthy subjects. Significant odds and risk ratio to atherosclerosis were observed for P. gingivalis, T. forsythia, T. denticola and P. nigrescens. Among the virulence genes, significance to atherosclerosis was observed for P. gingivalis type II fimA and T. forsythia bspA., Conclusion: The results of this study strongly correlate periodontal bacterial co-occurrence and periodontal bacterial adhesion factor to atherosclerosis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

As our knowledge of host-microbial interactions within the oral cavity increases, future treatments are likely to be more targeted. For example, efforts to target a single species or key virulence factors that they produce, while maintaining the natural balance of the resident oral microbiota that acts to modulate the host immune response would be an advantage. Targeted approaches may be directed at the black-pigmented anaerobes, Porphyromonas gingivalis and Prevotella intermedia, associated with periodontitis. Such pigments provide an opportunity for targeted phototherapy with high-intensity monochromatic light. Functional inhibition approaches, including the use of enzyme inhibitors, are also being explored to control periodontitis. More general disruption of dental plaque through the use of enzymes and detergents, alone and in combination, shows much promise. The use of probiotics and prebiotics to improve gastrointestinal health has now led to an interest in using these approaches to control oral disease. More recently the potential of antimicrobial peptides and nanotechnology, through the application of nanoparticles with biocidal, anti-adhesive and delivery capabilities, has been explored. The aim of this review is to consider the current status as regards non-conventional treatment approaches for oral infections with particular emphasis on the plaque-related diseases.

Background: Most clinical studies assume that the subgingival microbiota is similar from one geographic location to another. The purpose of the present investigation was to examine the composition of the subgingival microbiota in chronic periodontitis subjects from four countries., Method: Subjects with chronic periodontitis (N, Sweden=101; USA=115; Brazil=58; Chile=26) were recruited. Subjects were measured at baseline for plaque, gingivitis, bleeding on probing (BOP), suppuration, pocket depth (PD) and attachment level (AL) at six sites per tooth. Subgingival plaque samples taken from the mesial aspect of each tooth at baseline were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples=6036). % DNA probe counts comprised by each species was determined for each site and averaged across sites in each subject. Significance of differences in proportions of each species among countries was determined using ancova adjusting for age, mean pocket depth, gender and smoking status. p-Values were adjusted for multiple comparisons., Results: On average, all species were detected in samples from subjects in the four countries. Thirteen species differed significantly in adjusted mean proportions among countries even after adjusting for multiple comparisons. Porphyromonas gingivalis, one species that differed in proportions among countries, comprised adjusted means of 7.5, 11.9, 1.6 and 6.6% of the microbiota in subjects from Brazil, Chile, Sweden and USA (p<0.001), while mean proportions of Treponema denticola were 6.7, 4.2, 0.8 and 2.3, respectively (p<0.001). In contrast, a key periodontal pathogen, Tannerella forsythensis, exhibited mean proportions ranging from 6.2-8.5% and did not differ significantly among countries. Besides these species, prominent species in Brazil were Actinomyces naeslundii genospecies 1 and 2 (8.4%, 7.2%) and Prevotella intermedia (6.5%); in Chile, Prevotella melaninogenica (6.4%) and Neisseria mucosa (5.3%); in Sweden A. naeslundii genospecies 2 (8.4%), Capnocytophaga gingivalis (7.1%) and Peptostreptococcus micros (5.0%); in USA A. naeslundii genospecies 2 (7.5%), P. intermedia (6.8%) and C. gingivalis (6.1%)., Conclusions: The microbial profiles of subgingival plaque samples from chronic periodontitis subjects in four countries showed surprisingly marked differences. These differences persisted after adjusting for age, mean pocket depth, gender and smoking status., ((c) Blackwell Munksgaard, 2004)

Between 3-12 weeks after the beginning of supragingival plaque formation, a distinctive subgingival microflora predominantly made up of gram-negative, anaerobic bacteria and including some motile species, becomes established. In order to establish in a periodontal site, a species must be able to attach to one of several surfaces including the tooth (or host derived substances adhering to the tooth), the sulcular or pocket epithelium, or other bacterial species that are attached to these surfaces (Socransky and Haffajee 1991). Bacterial adhesion has demonstrated specificity in the mechanisms involved and studies have shown that there is a diversity of receptors on tooth surfaces, epithelial or other host cells and other bacteria. Recent studies have described bacterial complexes that are present in subgingival plaque and these studies are likely to help in current understanding of the complex ecology observed in dental plaque biofilm (Socransky, Haffajee et al. 1998). Bacterial interactions play important roles in species survival. Some interspecies relationships are favourable, in that one species produces growth factors for, or facilitates attachment of, another species. Other relationships are antagonistic due to competition for nutrients and binding sites, or to the production of substances that limit or prevent the growth of another species (Socransky and Haffajee 1991). A number of different bacterial interactions within plaque biofilm have been discussed. In the last 30-40 years, a vast amount of evidence has been published to suggest that bacteria are the primary aetiological agents of periodontal diseases. In the 1950s and early 1960s, periodontal treatment was based on the non-specific plaque hypothesis. However, the non-specific plaque hypothesis gave way after studies suggested that not all organisms in plaque are equally capable of causing destructive periodontal disease. Thus the concept of specificity re-emerged. Criteria for defining periodontal pathogens have been developed and include association, elimination, host response, virulence factors, animal studies and risk assessment (Haffajee and Socransky 1994). Until recently there were few consensus periodontal pathogens and trying to discriminate pathogenic from non-pathogenic species has been a difficult task for dental researchers for a variety of reasons. A discussion of the specific microbiota associated with gingivitis, chronic and aggressive periodontitis, NUG, HIV-associated periodontitis and implantitis has been presented. The bacteria associated with periodontal diseases are predominantly gram-negative anaerobic bacteria and may include A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, C. rectus, E. nodatum, P. micros, S. intermedius and Treponema sp. The bacterial numbers associated with disease are up to 10(5) times larger than those associated with health.

Periodontal disease result from mixed bacterial infections, in which both host resistance barriers and bacterial interactions are important. Approximately ten bacterial species are strongly implicated with various forms of periodontal disease, although species that cannot yet be cultivated are likely also to be relevant. New technologies have shown that pathogenic bacterial species are present in defined complexes within subgingival plaque, thus identifying specific targets for therapeutic intervention. In light of increasing antibiotic resistance amongst oral bacteria, new strategies for control of periodontal bacterial complexes must be developed that inhibit the bacterial factors necessary for colonization and destruction of host tissues.

Given the hypothesis that root caries is the result of acid formation by acidogenic micro-organisms, the present study was performed to relate sucrose-induced pH response of dental plaque on root surfaces to the microbial composition of the overlying plaque. Seventeen caries-active elderly Chinese with poor oral hygiene and with both sound and carious root surfaces were examined. Plaque pH was measured before and up to one hour after a controlled sucrose mouthrinse. Plaque samples for microbiologic analyses were collected from 2 sound and 2 or 3 carious pH-measurement sites in each subject. The prevalence of the following micro-organisms was assessed as % of total viable counts on Brucella agar: Prevotella intermedia, Prevotella melaninogenica, Fusobacterium nucleatum, Campylobacter rectus, Capnocytophaga spp., Actinomyces viscosus, Actinomyces naeslundi, Streptococcus spp., S. sanguis, S. mitis, S. mutans, S. sobrinus, Lactobacillus spp., and Candida spp. There was no difference in plaque pH response on sound and carious root surfaces. The plaque pH response was more pronounced in the maxilla than in the mandible for both sound and carious sites. There was no difference in microbial composition of dental plaque on sound and carious root surfaces. The pH response to sucrose was the same regardless of the presence or absence of mutans streptococci. Our results thus do not readily support the traditional concept of caries formation.

The aim of this study was to test the hypothesis that suspected periodontal pathogens form a minor component of the supragingival plaque of individuals without periodontal diseases. Twenty-one dental hygienist trainees with a mean age of 23.5 years were twice sampled for interdental plaque between 1st and 2nd molars in all quadrants. The samples were assessed for Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, Porphyromonas gingivalis, and the Prevotella intermedia/Prevotella nigrescens group of organisms. Bacteria of this group were predominantly P. nigrescens and showed both the highest prevalence (100%) and the highest colonization density of the investigated species. Seven of 21 samples harbored A. actinomycetemcomitans. Serotypes a, b, and c were found in three samples each, while serotype e was present in one sample. Three subjects had two different A. actinomycetemcomitans serotypes. Bacteroides forsythus and C. rectus were detected in 10 (48%) and nine (43%) subjects, respectively. The detected cell numbers accounted for approximately 0.01% to 1% of the sampled flora. In contrast, P. gingivalis was found only in a single sample, which in addition harbored B. forsythus, C. rectus, A. actinomycetemcomitans (serotypes b and e), and P. intermedia. These results suggest that the investigated periodontal bacteria are not "exogenous pathogens", but amphibiotic, opportunistic microorganisms which may have a natural habitat in the supragingival plaque of the interproximal area of molars.

Dental plaque forms naturally on teeth and is of benefit to the host by helping to prevent colonization by exogenous species. The bacterial composition of plaque remains relatively stable despite regular exposure to minor environmental perturbations. This stability (microbial homeostasis) is due in part to a dynamic balance of both synergistic and antagonistic microbial interactions. However, homeostasis can break down, leading to shifts in the balance of the microflora, thereby predisposing sites to disease. For example, the frequent exposure of plaque to low pH leads to inhibition of acid-sensitive species and the selection of organisms with an aciduric physiology, such as mutans streptococci and lactobacilli. Similarly, plaque accumulation around the gingival margin leads to an inflammatory host response and an increased flow of gingival crevicular fluid. The subgingival microflora shifts from being mainly Gram-positive to being comprised of increased levels of obligately anaerobic, asaccharolytic Gram-negative organisms. It is proposed that disease can be prevented or treated not only by targeting the putative pathogens but also by interfering with the processes that drive the breakdown in homeostasis. Thus, the rate of acid production following sugar intake could be reduced by fluoride, alternative sweeteners, and low concentrations of antimicrobial agents, while oxygenating or redox agents could raise the Eh of periodontal pockets and prevent the growth and metabolism of obligately anaerobic species. These views have been incorporated into a modified hypothesis (the "ecological plaque hypothesis") to explain the relationship between the plaque microflora and the host in health and disease, and to identify new strategies for disease prevention.

Localized prepubertal periodontitis has been described as a host-defect mediated form of bacterially induced periodontitis, with an early onset and rapid progression around a few teeth in children prior to puberty. To further our understanding of the etiology of this disease, we have examined the microbiological components of subgingival dental plaque in 9 children with localized prepubertal periodontitis to determine if patterns of putative pathogens existed, and have compared these results with those obtained from 4 children with no periodontitis. Subgingival plaque samples were plated onto a selective medium for Actinobacillus actinomycetemcomitans and onto a non-selective medium for anaerobes, and the predominant cultivable microbiota of 2 sites per child was determined. The subgingival microbiota of children with localized prepubertal periodontitis clearly differs from non-diseased children in the detection of high levels of several suspected pathogens, including A. actinomycetemcomitans, Bacteroides intermedius, Eikenella corrodens, and Capnocytophaga sputigena. These putative pathogens were found in various combinations. These findings suggest that localized prepubertal periodontitis is associated with specific subgingival bacteria which are generally not found in children without periodontitis.

Samples of subgingival plaque from 67 children, 5-7 years of age, were examined for the presence of certain suspected periodontal pathogenic species using the conventional technique of anaerobic sonification, dilution and spiral plating. When this technique was compared with a direct plating procedure which involved no preliminary dispersion and dilution of plaque specimens, it was found that the direct method resulted in double the frequency of children in whom black-pigmented Bacteroides (BPB) were detected and a 10-times increase in the number of subjects harbouring Actinobacillus actinomycetemcomitans. Samples from the tongue, tonsils and saliva were also plated using the direct technique. BPB were detected less commonly in the plaque specimens (61.3% of children) than in saliva (89.5%), or on the tongue (86.6%) and tonsils (97.1%). Expressed as percentages of a pooled sample of the total BPB population, the most frequently detected species in plaque were Bacteroides intermedius (44.4%) and Bacteroides melaninogenicus (48.0%). The most prevalent isolate in all other oral sites was B. melaninogenicus. Expressed as percentages of children in whom BPB were detected, the most frequently isolated species from plaque using the conventional dilution technique was B. intermedius (21.3%), whereas other BPB species were present in fewer than 5% of children. Fusobacterium nucleatum and Capnocytophaga species were isolated most frequently from plaque but were also commonly detected in the various other oral sites.