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Aim: Although the complexity of the oral ecology and the ecological differences between health and disease are well accepted, a clear view on the dynamics in relation to disease is lacking. In this study the prevalence and abundance of 20 key oral bacteria was assessed in health and disease and more importantly a closer look was given to the inter-bacterial relationships. Materials and Methods: A blinded microbiological database was analyzed in this cross-sectional, retrospective study. The database was constructed based on microbiological analyses of samples from 6308 patients, with gradations of periodontitis (healthy to periodontitis). Data concerning the abundance of 20 oral bacteria and probing pocket depth was provided. Results: P. gingivalis, T. forsythia, T. denticola, E. nodatum, P. micra and P. intermedia showed a clear increase in abundance and prevalence with increasing pocket depth. Correlation matrices illustrated that almost all microorganisms were in one way correlated to other species and most of these correlations were significant. Several beneficial bacteria showed strong correlations with other beneficial bacteria. Combining several beneficial bacteria could therefore lead to a stronger effect. Conclusion: Knowledge on bacterial correlations can pave the way for new treatment options focusing on restoring the shifted balance. ispartof: Journal of Clinical Periodontology vol:41 issue:1 pages:1-10 ispartof: location:United States status: published

DNA-based methodology for the identification and detection of specific bacteria in dental plaque offers advantages over culturing techniques. One drawback of current molecular techniques like real-time quantitative polymerase chain reaction (RT-QPCR) is that they are not able to distinguish between live or dead bacteria. To overcome this problem an assay was assessed to discriminate between viable or dead bacteria using DNA intercalating substances, propidium monoazide (PMA) and ethidium monoazide (EMA) in combination with RT-QPCR. The assay was tested on oral pathogens: Streptococcus mutans, Prevotella intermedia and Aggregatibacter actinomycetemcomitans. To determine the effectiveness of EMA and PMA, different concentrations (from 5 to 100 μg ml(-1)) of the substances were added to viable or heat-killed suspensions of both organisms (ranging from 10(8) to 10(4) colony-forming units ml(-1)). Afterwards, PMA was tested on mixtures of varying ratios of viable and dead cells. After DNA extraction, RT-QPCR was performed using species-specific primers. Both compounds inhibited PCR amplification from dead cells. The EMA treatment resulted in the largest signal decrease but EMA also inhibited DNA amplification from viable cells. For this reason, PMA was selected for use in further experiments. It was shown to be efficient in allowing selective PCR detection of only viable cells in mixtures containing both viable and dead cells. The amount of amplified DNA corresponded to the percentage of viable cells in the sample. The developed assay will potentially be useful for assessing bacterial loads remaining after disinfection protocols without interference by non-viable bacteria.

Teughels W, Loozen G, Quirynen M: Do probiotics offer opportunities to manipulate the periodontal oral microbiota? J Clin Periodontol 2011; 38 (Suppl. 11): 159–177. doi: 10.1111/j.1600-051X.2010.01665.x. Abstract Background: As in other fields of healthcare, probiotics have been introduced for prevention and treatment of periodontal diseases. Objective: This review was initiated to explore whether the use of probiotics can influence the periodontal microbiota and periodontal health. Materials and Methods: Literature on the mode of action of oral probiotics was reviewed and a systematic review was performed on the microbiological and clinical effects of oral probiotics on periodontal health. Results: Three animal and 11 in vivo human studies were retrieved. Six studies reported on microbiological effects whereas eight studies report on clinical effects. Seven studies were performed on healthy or gingivitis patients and four studies on periodontitis patients. Many of the retrieved studies are pilot in nature and with low quality. The high degree of heterogeneity between studies hampered analysis. Conclusion: Taking into consideration all limitations, the currently available data indicate an effect of probiotics on the oral microbiota and a more limited effect on clinical periodontal outcome measures. However, there is an urgent need for properly conducted clinical trials where probiotics are used as adjuncts to standard periodontal care, similar to antibiotics, using probiotic strains with, at least at an in vitro level, proven periodontal probiotic effects.

Recently, the predation of Bdellovibrio bacteriovorus on a periodontal pathogen has been described. The current study explores the potential antimicrobial activity of a range of predatory bacteria against key periodontal pathogens. A number of representatives from the Bdellovibrio, Bacteriovorax and Peredibacter lineages (called 'BALOs') were tested for their activity towards a group of key periodontal pathogens and an optimal multiplicity of infection was established. As the oral cavity contains a wide variety of bacteria that are not preyed upon, it was investigated if they can have an effect on the predation efficiency of BALOs. It was concluded that a number of important variables involved in bacterial predation are found to be compatible with the composition of the oral microbiota. This finding makes the case for continued study of the potential for BALOs to combat periodontal pathogens.

The inflammatory response plays an important role in the tissue destruction associated with periodontitis. Bacterial species can regulate the inflammatory response of host cells, triggered by pathogens. It was hypothesized that also in the field of oral microbiology/immunology such effects of bacterial interactions on inflammatory host cell responses might be present. In this study the effect of beneficial, commensal and pathogenic species on Aggregatibacter actinomycetemcomitans-induced interleukin-8 (IL-8) production by human cells was investigated. The beneficial species, Streptococcus mitis, Streptococcus salivarius and Streptococcus sanguinis, were able to lower the IL-8 production triggered by A. actinomycetemcomitans. The inhibitory effect was also achieved by the application of streptococcal supernatants. In contrast, the commensal Streptococcus gordonii caused no reduction, and the pathogen Fusobacterium nucleatum increased the IL-8 production by the host cells. These results show that bacterial species can influence the inflammatory response of host cells triggered by infection with A. actinomycetemcomitans. ispartof: Journal of Dental Research vol:88 issue:11 pages:1026-1030 ispartof: location:United States status: published

Quantification of Bdellovibrio-and-like organisms (BALOs) by microbial culturing has a number of substantial drawbacks. Therefore a quantitative PCR (qPCR) assay was designed for the culture-independent enumeration of the Bdellovibrionaceae. After optimization, the dynamic range of the qPCR assay was assessed, the specificity was evaluated and a comparison with quantitative microbial culturing was made. To evaluate the suitability of the qPCR assay for analysing environmental samples, fresh water samples were investigated by microbial culturing and by the qPCR assay. The results revealed a substantial difference between the two techniques and indicate that most Bdellovibrionaceae cells are left undetected in environmental samples when only current microbial culturing techniques are used. The application of this new technique is therefore likely to confirm the hitherto underestimated sizes and roles of predatory bacterial populations in nature. ispartof: Environmental microbiology reports vol:1 issue:4 pages:228-233 ispartof: location:United States status: published

The predation of Bdellovibrio bacteriovorus on different periodontal pathogens has already been described. However, it is necessary to consider the polymicrobial nature of periodontal disease. The current study explores the predation of Bdellovibrio on oral pathogens organized in multispecies communities. The effect of the predator was evaluated on in vitro six species communities with microbial culturing. Additionally, the effect on ex vivo subgingival plaque and saliva samples from periodontitis patients was assessed. In the latter experiment results were examined with microbial culturing, quantitative polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE). The latter technique was used to get an overview of the whole mixed microbial population. Results showed that even in more complex models, B. bacteriovorus was still able to predate on F. nucleatum and A. actinomycetemcomitans. However predation on P. intermedia and P. gingivalis could not be validated in multispecies models. The effect of Bdellovibrio was not restricted to the target bacteria. Changes in the overall ecology of the different models were evident. It could be concluded that the efficiency of predation decreased when complexity of the models increased. However, B. bacteriovorus was able to attack two important oral pathogens, F. nucleatum, and A. actinomycetemcomitans, even when present in ex vivo clinical samples. These effects still have to be validated in in vivo models to see the impact of Bdellovibrio on the whole bacterial ecology. publisher: Elsevier articletitle: Effect of Bdellovibrio bacteriovorus HD100 on multispecies oral communities journaltitle: Anaerobe articlelink: http://dx.doi.org/10.1016/j.anaerobe.2014.09.011 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved. ispartof: Anaerobe vol:35 issue:Pt A pages:45-53 ispartof: location:England status: published

The outgrowth of Porphyromonas gingivalis within the inflammatory subgingival plaque is associated with periodontitis characterized by periodontal tissue destruction, loss of alveolar bone, periodontal pocket formation, and eventually, tooth loss. Potential virulence factors of P. gingivalis are peptidylarginine deiminase (PPAD), an enzyme modifying free or peptide-bound arginine to citrulline, and the bacterial proteases referred to as gingipains (Rgp and Kgp). Chemokines attract leukocytes during inflammation. However, posttranslational modification (PTM) of chemokines by proteases or human peptidylarginine deiminases may alter their biological activities. Since chemokine processing may be important in microbial defense mechanisms, we investigated whether PTM of chemokines by P. gingivalis enzymes occurs. Upon incubation of interleukin-8 (IL-8; CXCL8) with PPAD, only minor enzymatic citrullination was detected. In contrast, Rgp rapidly cleaved CXCL8 in vitro . Subsequently, different P. gingivalis strains were incubated with the chemokine CXCL8 or CXCL10 and their PTMs were investigated. No significant CXCL8 citrullination was detected for the tested strains. Interestingly, although considerable differences in the efficiency of CXCL8 degradation were observed with full cultures of various strains, similar rates of chemokine proteolysis were exerted by cell-free culture supernatants. Sequencing of CXCL8 incubated with supernatant or bacteria showed that CXCL8 is processed into its more potent forms consisting of amino acids 6 to 77 and amino acids 9 to 77 (the 6-77 and 9-77 forms, respectively). In contrast, CXCL10 was entirely and rapidly degraded by P. gingivalis , with no transient chemokine forms being observed. In conclusion, this study demonstrates PTM of CXCL8 and CXCL10 by gingipains of P. gingivalis and that strain differences may particularly affect the activity of these bacterial membrane-associated proteases.

Background: The aim of the current study was to compare the prevalence of commensal bacteria, with beneficial properties, for healthy and diseased individuals and additionally to examine the inhibitory effect of some commercial dietary probiotics on periodontopathogens comparing this inhibitory effect with that of orally derived beneficial bacteria. Methods: Subgingival plaque samples from 35 patients (healthy and periodontitis patients), were analyzed. Growth inhibition of the periodontal pathogens Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans was examined using the agar overlay technique and agar well diffusion method. The quantification of the inhibitory effect was checked with the agar well diffusion method. Results: Using the agar overlay technique the prevalence of strains antagonistic towards P. gingivalis, A. actinomycetemcomitans and F. nucleatum was found to be higher in healthy individuals than in individuals suffering from periodontitis, this could not be validated by the agar well diffusion assay. Compared with the antagonistic activity of the isolated strains, the probiotic strains overall showed a stronger inhibition of the periodontal pathogens. Conclusion: It was shown that some oral bacteria can cause antagonism towards periodontopathogens and these observations underline the therapeutic potential of applications that stimulate oral health by the application of beneficial effector strains. ispartof: Journal of periodontology vol:84 issue:6 pages:801-811 ispartof: location:United States status: published

As in other fields of healthcare, probiotics have been introduced for prevention and treatment of periodontal diseases.This review was initiated to explore whether the use of probiotics can influence the periodontal microbiota and periodontal health.Literature on the mode of action of oral probiotics was reviewed and a systematic review was performed on the microbiological and clinical effects of oral probiotics on periodontal health.Three animal and 11 in vivo human studies were retrieved. Six studies reported on microbiological effects whereas eight studies report on clinical effects. Seven studies were performed on healthy or gingivitis patients and four studies on periodontitis patients. Many of the retrieved studies are pilot in nature and with low quality. The high degree of heterogeneity between studies hampered analysis.Taking into consideration all limitations, the currently available data indicate an effect of probiotics on the oral microbiota and a more limited effect on clinical periodontal outcome measures. However, there is an urgent need for properly conducted clinical trials where probiotics are used as adjuncts to standard periodontal care, similar to antibiotics, using probiotic strains with, at least at an in vitro level, proven periodontal probiotic effects.

In de uterus is de menselijke foetus steriel, maar na passage door het geboortekanaal gaan er zich vaginale en fecale micro-organismen nestelen. Ook de kolonisatie van de mondholte start kort na de geboorte. Slechts enkele uren nadien wordt de steriele mondholte gekoloniseerd door lage aantallen van vooral facultatieve en aerobe bacterien (Socransky en Manganiello, 1971). Vanaf de tweede dag kunnen er reeds anaerobe bacterien worden gedetecteerd in de tandeloze mond van de zuigeling (Rotimi en Duerden, 1981). Binnen twee weken heeft zich een bijna mature microbiota gevestigd in de darm van de pasgeborene. Na het spenen (> 2 jaar), is de hele menselijke microbiele flora gevormd. Deze flora is een zeer complexe verzameling van ongeveer 1014 microorganismen. Vanaf dat moment bevat ons lichaam tien keer meer bacterien dan cellen. In het algemeen leven deze bacterien in harmonie met de gastheer, maar onder bijzondere omstandigheden (verhoogde massa en/of pathogeni- citeit, en/of verminderde gastheerrespons) kan ziekte optreden. Vaak hebben bacterien en gastheercellen een commensale relatie, die voordelig is voor beide partijen.

INTRODUCTION: Microbial interactions are considered to be important for bacterial colonization. Interactions that inhibit colonization of pathogens could possibly be used as a new treatment approach for periodontitis. The aim of this study was to test this hypothesis on soft surfaces in vitro, taking into account the hydrodynamic forces continuously present in vivo. METHODS: Cultured epithelial cells were precolonized with Streptococcus sanguinis KTH-4, Streptococcus cristatus CC5A, Streptococcus salivarius TOVE and Streptococcus mitis BMS before Aggregatibacter actinomycetemcomitans colonization. Experiments were performed in a modified Robbins-device-type flow cell. Bacterial colonization and the number of epithelial cells were evaluated by microbial culturing and quantitative polymerase chain reaction. RESULTS: The streptococci were able to inhibit A. actinomycetemcomitans colonization on soft tissue surfaces under flow conditions. Statistically significant differences were found between streptococcal pretreatments and the controls, with the most pronounced effect caused by S. sanguinis. CONCLUSION: These data confirm the possibility of applying beneficial bacteria in periodontal treatment. ispartof: Oral Microbiology and Immunology vol:24 issue:5 pages:390-5 ispartof: location:Denmark status: published

Root resorption of maxillary lateral incisors caused by erupting canines is well known and a relatively common phenomenon. However, much debate and conflicting evidence exists with regard to the actual resorption trigger and potential etiological factors involved. Consequently, there are no obvious clinical clues concerning prevention and diagnosis as well as subsequent treatment decisions. The introduction of cone beam computer tomography has recently allowed drawing a new and much more documented light on the diagnostic and therapeutic strategies. However, no investigations have determined that this new information may result in another and better diagnostic approach and an improved treatment outcome. Therefore, the present review will attempt to summarize the existing evidence on two- and three-dimensional images and try to link the radiological observations to any further preventive, diagnostic, and/or therapeutic measures. Detection thresholds, accuracy, and reliability of impacted canine localization and neighboring root resorption risks will also be considered. This review demonstrates how adding a third-dimension to the radiographic information may notably alter the prevalence of root resorptions and descriptions of this prevalence. In any case, further investigation is needed to determine resorption detection thresholds in various two-dimensional and three-dimensional imaging techniques, as well as to determine therapeutic thresholds and criteria for strategic tooth extraction based on radiographic manifest and not manageable resorption lesions.