Pursuing new periodontal pathogens with an improved RNA-oligonucleotide quantification technique (ROQT)

OBJECTIVE

The aim of this study was to optimize the sensitivity, specificity and cost-effectiveness of the RNA-Oligonucleotide Quantification Technique (ROQT) in order to identify periodontal pathogens that remain unrecognized or uncultured in the oral microbiome.

DESIGN

Total nucleic acids (TNA) were extracted from subgingival biofilm samples using an automated process. RNA, DNA and Locked Nucleic Acid (LNA) digoxigenin-labeled oligonucleotide probes targeting 5 cultivated/named species and 16 uncultivated or unnamed bacterial taxa were synthesized. Probe specificity was determined by targeting 96 oral bacterial species; sensitivity was assessed using serial dilutions of reference bacterial strains. Different stringency temperatures were compared and new standards were tested. The tested conditions were evaluated analyzing samples from periodontally healthy individuals, and patients with moderate or severe periodontitis.

RESULTS

The automated extraction method at 63⁰C along with LNA-oligunucleotides probes, and use of reverse RNA sequences for standards yielded stronger signals without cross-reactions. In the pilot clinical study, the most commonly detected uncultivated/unrecognized species were Selenomonas sp. HMT 134, Prevotella sp. HMT 306, Desulfobulbus sp. HMT 041, Synergistetes sp. HMT 360 and Bacteroidetes HMT 274. In the cultivated segment of the microbiota, the most abundant taxa were T. forsythia HMT 613 and Fretibacterium fastidiosum (formerly Synergistetes) HMT 363.

CONCLUSIONS

In general, samples from severe patients had the greatest levels of organisms. Classic (T. forsythia, P. gingivalis) and newly proposed (F. alocis and Desulfobulbus sp. HMT 041) pathogens were present in greater amounts in samples from severe periodontitis sites, followed by moderate periodontitis sites.

Response to comment on "Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis"

Antibodies to leukotoxin A are markers that link Aggregatibacter actinomycetemcomitans-associated periodontitis and rheumatoid arthritis.

Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis

A bacterial etiology of rheumatoid arthritis (RA) has been suspected since the beginnings of modern germ theory. Recent studies implicate mucosal surfaces as sites of disease initiation. The common occurrence of periodontal dysbiosis in RA suggests that oral pathogens may trigger the production of disease-specific autoantibodies and arthritis in susceptible individuals. We used mass spectrometry to define the microbial composition and antigenic repertoire of gingival crevicular fluid in patients with periodontal disease and healthy controls. Periodontitis was characterized by the presence of citrullinated autoantigens that are primary immune targets in RA. The citrullinome in periodontitis mirrored patterns of hypercitrullination observed in the rheumatoid joint, implicating this mucosal site in RA pathogenesis. Proteomic signatures of several microbial species were detected in hypercitrullinated periodontitis samples. Among these, Aggregatibacter actinomycetemcomitans (Aa), but not other candidate pathogens, induced hypercitrullination in host neutrophils. We identified the pore-forming toxin leukotoxin A (LtxA) as the molecular mechanism by which Aa triggers dysregulated activation of citrullinating enzymes in neutrophils, mimicking membranolytic pathways that sustain autoantigen citrullination in the RA joint. Moreover, LtxA induced changes in neutrophil morphology mimicking extracellular trap formation, thereby releasing the hypercitrullinated cargo. Exposure to leukotoxic Aa strains was confirmed in patients with RA and was associated with both anticitrullinated protein antibodies and rheumatoid factor. The effect of human lymphocyte antigen-DRB1 shared epitope alleles on autoantibody positivity was limited to RA patients who were exposed to Aa These studies identify the periodontal pathogen Aa as a candidate bacterial trigger of autoimmunity in RA.

Exploring the microbiome of healthy and diseased peri-implant sites using Illumina sequencing

AIM

To compare the microbiome of healthy (H) and diseased (P) peri-implant sites and determine the core peri-implant microbiome.

MATERIALS AND METHODS

Submucosal biofilms from 32 H and 35 P sites were analysed using 16S rRNA sequencing (MiSeq, Illumina), QIIME and HOMINGS. Differences between groups were determined using principal coordinate analysis (PCoA), t tests and Wilcoxon rank sum test and FDR-adjusted. The peri-implant core microbiome was determined.

RESULTS

PCoA showed partitioning between H and P at all taxonomic levels. Bacteroidetes, Spirochetes and Synergistetes were higher in P, while Actinobacteria prevailed in H (p < .05). Porphyromonas and Treponema were more abundant in P while Rothia and Neisseria were higher in H (p < .05). The core peri-implant microbiome contained Fusobacterium, Parvimonas and Campylobacter sp. T. denticola, and P. gingivalis levels were higher in P, as well as F. alocis, F. fastidiosum and T. maltophilum (p < .05).

CONCLUSION

The peri-implantitis microbiome is commensal-depleted and pathogen-enriched, harbouring traditional and new pathogens. The core peri-implant microbiome harbours taxa from genera often associated with periodontal inflammation.

Low Biofilm Lysine Content in Refractory Chronic Periodontitis

BACKGROUND

Chronic periodontitis is controlled without antibiotics by scaling and root planing (SRP) to remove dental biofilm. It has been previously reported that the epithelial barrier to bacterial proinflammatory products is impaired when biofilm lysine falls below the minimal content of normal blood plasma. Aims were to examine whether being refractory and requiring antibiotics to supplement SRP were associated with low biofilm lysine contents.

METHODS

Sixteen patients with periodontitis and six periodontally healthy volunteers (HVs) (respective mean ages: 57 ± 6 and 36 ± 8 years) were examined. Patients with periodontitis received SRP and surgery, and HVs received prophylaxis. At quarterly maintenance or prophylaxis visits during the subsequent year, therapeutic response was good (GR, n = 9) or poor (PR, n = 7; including five cigarette smokers). Biofilm cadaverine, lysine, and other amino acid (AA) contents were determined by liquid chromatography. Cadaverine mole fraction of lysine plus cadaverine (CF) indicated biofilm lysine decarboxylase activity.

RESULTS

Biofilm lysine was 0.19 ± 0.10 and 0.20 ± 0.09 μmol/mg in GRs and HVs, but 0.07 ± 0.03 μmol/mg in PRs (Kruskal-Wallis: P <0.01). All AAs were depleted in biofilm from smokers, but only lysine was depleted in biofilm from non-smokers. CF was inversely associated with clinical attachment level (CAL) at baseline before therapy in all patients (R² = 0.28, P <0.01) and with CAL change after therapy in GR (R² = 0.49, P <0.05). Lysine and cadaverine contents discriminated PRs from GRs and HVs (Wilks' λ = 0.499, P <0.012).

CONCLUSIONS

Refractory responses requiring antibiotic therapy result from smoking and/or microbial infections that starve the biofilm and epithelial attachment of lysine. Biofilm CF is associated with periodontitis severity pretherapy and extent of therapeutic response post-therapy.

Effects of triclosan on host response and microbial biomarkers during experimental gingivitis

AIM

This exploratory randomized, controlled clinical trial sought to evaluate anti-inflammatory and -microbial effects of triclosan during experimental gingivitis as assessed by host response biomarkers and biofilm microbial pathogens.

MATERIALS AND METHODS

Thirty participants were randomized to triclosan or control dentifrice groups who ceased homecare for 21 days in an experimental gingivitis (EG) protocol. Plaque and gingival indices and saliva, plaque, and gingival crevicular fluid (GCF) were assessed/collected at days 0, 14, 21 and 35. Levels and proportions of 40 bacterial species from plaque samples were determined using checkerboard DNA-DNA hybridization. Ten biomarkers associated with inflammation, matrix degradation, and host protection were measured from GCF and saliva and analysed using a multiplex array. Participants were stratified as "high" or "low" responders based on gingival index and GCF biomarkers and bacterial biofilm were combined to generate receiver operating characteristic curves and predict gingivitis susceptibility.

RESULTS

No differences in mean PI and GI values were observed between groups and non-significant trends of reduction of host response biomarkers with triclosan treatment. Triclosan significantly reduced levels of A. actinomycetemcomitans and P. gingivalis during induction of gingivitis.

CONCLUSIONS

Triclosan reduced microbial levels during gingivitis development (ClinicalTrials.gov NCT01799226).

Abstract 858: Periodontal bone loss and risk of epithelial ovarian cancer in the Nurses’ Health Study

Periodontitis, a chronic inflammatory reaction to dysbiotic oral microbiota, is common in the adult population in the United States. It is associated with increased risk of several medical conditions, including cardiovascular diseases, and potentially with lung, oral and pancreatic cancer. One of the proposed mechanisms behind these associations is systemic inflammation, which has also been implied in ovarian cancer etiology. We investigated association between periodontal bone loss, a marker of periodontitis, and risk of epithelial ovarian cancer among 60,560 participants of the Nurses’ Health Study. We did not observe an increased risk of ovarian cancer among participants suffering from periodontal bone loss (HR = 0.86, 95% CI: 0.64-1.15). Association was unchanged after adjusting for numerous factors including smoking. Among women younger than 69 years periodontal bone loss was associated with a 40% (HR = 0.60, 95% CI: 0.36-0.98) decreased ovarian cancer risk, while there was no association in those older than 69 (HR = 1.09, 95% CI: 0.75-1.58), although this difference did not reach a statistical significance (p-heterogeneity = 0.06). There also was a suggestive decreased risk for serous tumors (HR = 0.76, 95% CI: 0.53-1.09). The number of natural teeth and number of root canals, which are other metrics of oral health, were not associated with ovarian cancer risk. Our results do not support an increased risk of ovarian cancer for women with periodontal bone loss; however, given the unexpected associations in younger women, further research is warranted.

Note: This abstract was not presented at the meeting.

Citation Format: Ana Babic, Elizabeth M. Poole, Kathryn L. Terry, Daniel W. Cramer, Ricardo P. Teles, Shelley S. Tworoger. Periodontal bone loss and risk of epithelial ovarian cancer in the Nurses’ Health Study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 858. doi:10.1158/1538-7445.AM2015-858

Periodontal bone loss and risk of epithelial ovarian cancer

PURPOSE

Periodontitis, a chronic inflammatory response to pathogenic bacteria in the oral microbiome, is common among adults. It is associated with several medical conditions, including cardiovascular diseases, and potentially with esophageal, lung, oral, and pancreatic cancer. One of the proposed mechanisms behind these associations is systemic inflammation, which has also been implicated in ovarian cancer etiology. The aim of this study was to evaluate association between ovarian cancer and periodontal bone loss.

METHODS

The association between periodontal bone loss, a marker of periodontitis, and risk of epithelial ovarian cancer was estimated among 60,560 participants of the prospective Nurses' Health Study using Cox proportional hazards analysis. Competing risks analysis was used to estimate association by histologic subtype.

RESULTS

We did not observe an increased risk of ovarian cancer among participants with periodontal bone loss (HR 0.86, 95% CI 0.64-1.15). Among women younger than 69 years, periodontal bone loss was associated with a 40 % (HR 0.60, 95% CI 0.36-0.98) decreased ovarian cancer risk, while there was no association in women older than 69 (HR 1.09, 95% CI 0.75-1.58), although this difference did not reach statistical significance (p-heterogeneity = 0.06). We observed a suggestive decreased risk for serous tumors (HR 0.76, 95% CI 0.53-1.09). The number of natural teeth and root canals, other metrics of oral health, were not associated with ovarian cancer risk.

CONCLUSION

Our results do not support an increased ovarian cancer risk in women with periodontal bone loss; however, there was a significant decrease in risk in women younger than 69. Given the unexpected association between periodontal bone loss and ovarian cancer risk in younger women, further research is warranted.

Levels of gingival crevicular fluid matrix metalloproteinases in periodontally compromised teeth under orthodontic forces

OBJECTIVE

To examine levels of matrix metalloproteinases (MMPs)-1, -2, -3, -7, -8, -12, and -13 in the gingival crevicular fluid (GCF) of periodontally compromised teeth at different time points during orthodontic movement.

MATERIALS AND METHODS

Ten controlled periodontitis subjects were submitted to orthodontic treatment. One dental arch was subjected to orthodontic movement, and teeth in the opposite arch were used as controls. GCF samples were collected from the lingual sites of two movement and two control incisors 1 week before orthodontic activation (-7 d), immediately after orthodontic activation, and after 1 hour, 24 hours, and 7, 14, and 21 days. Multiplexed bead immunoassay was used to measure MMPs in GCF. Data were analyzed using Friedman and Wilcoxon statistical tests.

RESULTS

The only significant change found over time was in the levels of MMP-1 in the movement group (P < .05). When the two groups were compared after activation, the only statistically significant difference found was in levels of MMP-12 24 hours after activation (P < .05).

CONCLUSIONS

Our findings suggested that the orthodontic movement of periodontally compromised teeth without active pockets did not result in significant changes in the GCF levels of MMPs.

Immunological profile of periapical endodontic infections from HIV- and HIV+ patients

AIM

To evaluate CD4(+) CD28(+) and CD8(+) T-cell genes and the gene expression of IFN-γ, TNF-α, IL-1-β, IL-17A, IL-10, CCL-2/MCP-1, CCL-4, CCL-5 (RANTES), CXCR4, CCR5 and RANKL from cells in the periapical interstitial fluid from root canal infections in healthy patients (HIV-) and HIV-positive individuals (HIV+).

METHODOLOGY

Subjects included 20 HIV- and 23 HIV+ patients referred to the School of Dentistry at the Universidade Federal de Minas Gerais (Belo Horizonte, MG, Brazil). Almost all HIV+ patients were undergoing highly active antiretroviral therapy (HAART). Clinical samples were taken from teeth with pulp necrosis, and no patients had acute periapical symptoms at the time of the appointments. After cleaning and drying, 3 paper points were introduced into the root canal, passing passively through the root apex (2 mm) into the periapical tissues for 1 min. The samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize those gene expressions using real-time PCR.

RESULTS

Significantly higher levels of CD4(+) CD28(+) and CD8(+) T cells in teeth with restrained bacterial loads (second collection) compared with the first collection were observed in both HIV- and HIV+ samples. In HIV- patients, an increase in IL-10 and CXCR4 expression was demonstrated as well as a decrease in pro-inflammatory cytokines such as RANKL, IFN-γ, IL1-β and CCL5. However, in HIV+ patients an increase in cytokines IFN-γ, IL-1-β, TNF-α and IL-17A, and chemokines CCL-2, CXCR4 and CCR5 were observed. The chemokine CCL-5 was not detected in HIV+ individuals.

CONCLUSIONS

These findings suggest that after reducing the root canal bacterial load in HIV- individuals an anti-inflammatory response is generated whilst in HIV+ patients a pro-inflammatory response is sustained in the periapical area.

Comparison of microbial changes in early redeveloping biofilms on natural teeth and dentures

BACKGROUND

Surfaces and fluids can affect oral bacterial colonization. The aim of this study is to compare redeveloping biofilms on natural teeth and dentures.

METHODS

Supragingival plaque samples were taken from 55 dentate individuals and the denture teeth of 62 edentulous individuals before and after professional cleaning. Also, samples from seven "teeth" (samples included dentures) in randomly selected quadrants were collected after 1, 2, 4, and 7 days of no oral hygiene. Samples were analyzed using checkerboard DNA-DNA hybridization. Counts and proportions of 41 bacterial taxa were determined at each time point, and significant differences were determined using the Mann-Whitney U test. Ecological succession was determined using a modified moving window analysis.

RESULTS

Mean total DNA probe counts were similar precleaning but were higher in dentate individuals at all post-cleaning visits (P <0.01). Precleaning edentate biofilms had higher counts and proportions of Streptococcus mitis, Streptococcus oralis, and Streptococcus mutans, whereas dentate individuals had higher proportions of Tannerella forsythia, Selenomonas noxia, and Neisseria mucosa. By day 2, mean counts of all taxa were higher in natural teeth, and most remained higher at day 7 (P <0.01). Succession was more rapid and complex in dentate individuals. Both groups demonstrated increased proportions of S. mitis and S. oralis by day 1. N. mucosa, Veillonella parvula, and Eikenella corrodens increased in both groups, but later in samples from edentate individuals.

CONCLUSIONS

"Mature" natural and denture teeth biofilms have similar total numbers of bacteria but different species proportions. Post-cleaning biofilm redevelopment is more rapid and more complex on natural teeth than on denture teeth.

Microbiologic profile of endodontic infections from HIV- and HIV+ patients using multiple-displacement amplification and checkerboard DNA-DNA hybridization

OBJECTIVE

To compare the microbiota of endodontic infections in necrotic pulp from HIV-negative and HIV-positive subjects.

MATERIALS AND METHODS

Root canal samples from necrotic pulp were collected from 40 HIV- and 20 HIV+ subjects. Pulps were amplified using multiple displacement amplification (MDA). Then, checkerboard DNA-DNA hybridization was employed to assess the levels of 107 microbial taxa. The percentage of DNA probe count and the percentage of teeth colonized by each test species were investigated. Significant differences between groups regarding proportions of taxa and prevalence of the test species were sought using the Mann-Whitney test and the Chi-square analysis, respectively.

RESULTS

The most prevalent taxa detected were Dialister pneumosintes, Stenotrophomonas maltophilia, Streptococcus sobrinus, Corynebacterium diphteriae, and Helicobacter pylori among HIV- subjects and D. pneumosintes, Prevotella tannerae, Porphyromonas gingivalis, Parvimonas micra, Prevotella nigrescens, and Corynebacterium diphtheriae among HIV+ individuals. D. pneumosintes, C. diphtheria, and C. albicans were the most abundant species in the HIV- group, whereas the predominant taxa in HIV+ samples were P. tannerae, D. pneumosintes and Olsenella uli. P. tannerae, O. uli, Veilonella dispar, Bacteroides fragilis, and Actinomyces meyeri were significantly more abundant in HIV+ samples.

CONCLUSIONS

There were significant differences in the prevalence and proportions of specific microbial taxa between HIV- and HIV+ individuals. The root canal microbiota may represent a reservoir of important oral and medical pathogens, mainly in HIV+ individuals.

Relationships among interleukin-6, tumor necrosis factor-α, adipokines, vitamin D, and chronic periodontitis

BACKGROUND

The aim of this study is to explore relationships among serum adipokines, vitamin D, and clinical and microbial parameters of chronic periodontitis before and after treatment.

METHODS

Weight, height, and smoking status were recorded for 56 patients with chronic periodontitis. Plaque, gingivitis, bleeding on probing, suppuration, probing depth, and clinical attachment level were measured at all teeth present. Subgingival biofilm samples from each tooth were analyzed for levels of 40 bacterial species using checkerboard DNA-DNA hybridization. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-α, adiponectin, leptin, resistin, and vitamin D were measured at baseline. Sample collection was then performed in a subset of the population 6 months after therapy (n = 17). Serum samples were analyzed using enzyme-linked immunosorbent assay and immunoassays. Differences in clinical, microbial, and serum factors among groups were sought using the Mann-Whitney U test. Correlations among factors were evaluated using regression analysis. Effects of therapy were sought using the Wilcoxon signed rank test.

RESULTS

There were positive correlations between adiponectin/vitamin D and between IL-6/leptin, negative correlations between IL-6/vitamin D and leptin/vitamin D, but no associations between serum analytes and clinical or microbial parameters. Sex and body mass index were associated with levels of adipokines. Periodontal therapy improved clinical and microbiologic parameters but did not influence the levels of serum analytes.

CONCLUSION

Adipokines and IL-6 levels were affected by sex and body mass index. Serum analytes were not influenced by periodontal therapy.

Early microbial succession in redeveloping dental biofilms in periodontal health and disease

BACKGROUND AND OBJECTIVE

The development of dental biofilms after professional plaque removal is very rapid. However, it is not clear whether most bacterial species return at similar rates in periodontally healthy and periodontitis subjects or if there are differences in bacterial recolonization between supragingival and subgingival biofilms in periodontal health and disease.

MATERIAL AND METHODS

Supragingival and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects immediately after professional cleaning. Samples were taken again from seven teeth in randomly selected quadrants after 1, 2, 4 and 7 d of no oral hygiene and analyzed using checkerboard DNA-DNA hybridization. The percentage of DNA probe counts were averaged within subjects at each time-point. Ecological succession was determined using a modified moving-window analysis.

RESULTS

Succession in supragingival biofilms from subjects with periodontitis and from healthy individuals was similar. At 1 d, Streptococcus mitis and Neisseria mucosa showed increased proportions, followed by Capnocytophaga gingivalis, Eikenella corrodens, Veillonella parvula and Streptococcus oralis at 1-4 d. At 4-7 d, Campylobacter rectus, Campylobacter showae, Prevotella melaninogenica and Prevotella nigrescens became elevated. Subgingival plaque redevelopment was slower and very different from supragingival plaque redevelopment. Increased proportions were first observed for S. mitis, followed by V. parvula and C. gingivalis and, at 7 d, by Capnocytophaga sputigena and P. nigrescens. No significant increase in the proportions of periodontal pathogens was observed in any of the clinical groups or locations.

CONCLUSION

There is a defined order in bacterial species succession in early supragingival and subgingival biofilm redevelopment after professional cleaning.

Microbial shifts during dental biofilm re-development in the absence of oral hygiene in periodontal health and disease

AIM

To monitor microbial shifts during dental biofilm re-development.

MATERIALS AND METHODS

Supra- and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects at baseline and immediately after tooth cleaning. Samples were taken again from seven teeth in randomly selected quadrants during 1, 2, 4 and 7 days of no oral hygiene. Samples were analysed using checkerboard DNA-DNA hybridization. Species counts were averaged within subjects at each time point. Significant differences in the counts between healthy and periodontitis subjects were determined using the Mann-Whitney test.

RESULTS

The total supra- and subgingival counts were significantly higher in periodontitis on entry and reached or exceeded the baseline values after day 2. Supragingival counts of Veillonella parvula, Fusobacterium nucleatum ss vincentii and Neisseria mucosa increased from 2 to 7 days. Subgingival counts were greater for Actinomyces, green and orange complex species. Significant differences between groups in supragingival counts occurred for 17 of 41 species at entry, 0 at day 7; for subgingival plaque, these values were 39/41 taxa at entry, 17/41 at day 7.

CONCLUSIONS

Supragingival plaque re-development was similar in periodontitis and health, but subgingival species recolonization was more marked in periodontitis.

RNA-oligonucleotide quantification technique (ROQT) for the enumeration of uncultivated bacterial species in subgingival biofilms

Approximately 35% of the species present in subgingival biofilms are as yet uncultivated, so their role in periodontal pathogenesis is unknown. The aim of the present study was to develop a high throughput method to quantify a wide range of cultivated and uncultivated taxa in subgingival biofilm samples associated with periodontal disease or health. Oligonucleotides targeting the 16S ribosomal DNA gene were designed, synthesized and labeled with digoxigenin. These probes were hybridized with the total nucleic acids of pure cultures or subgingival biofilm samples. Target species included cultivated taxa associated with periodontal health and disease, as well as uncultivated species, such as TM7 sp. OT 346, Mitsuokella sp. OT 131 and Desulfobulbus sp. OT 041. Sensitivity and specificity of the probes were determined. A Universal probe was used to assess total bacterial load. Sequences complementary to the probes were used as standards for quantification. Chemiluminescent signals were visualized after film exposure or using a CCD camera. In a pilot clinical study, 266 subgingival plaque samples from eight periodontally healthy people and 11 patients with periodontitis were examined. Probes were specific and sensitivity reached 10(4) cells. Fusobacterium nucleatum ss. polymorphum and Actinomyces gerencseriae were the most abundant cultivated taxa in clinical samples. Among uncultivated/unrecognized species, Mitsuokella sp. OT 131 and Prevotella sp. OT 306 were the most numerous. Porphyromonas gingivalis and Desulfobulbus sp. OT 041 were only detected in patients with periodontitis. Direct hybridization of total nucleic acids using oligonucleotide probes permitted the quantification of multiple cultivated and uncultivated taxa in mixed species biofilm samples.

Microbiota of deciduous endodontic infections analysed by MDA and Checkerboard DNA-DNA hybridization

AIMS

To evaluate the microbiota of endodontic infections in deciduous teeth by Checkerboard DNA-DNA hybridization after uniform amplification of DNA in samples by multiple displacement amplification (MDA).

METHODOLOGY

Forty samples from the root canal system of deciduous teeth exhibiting pulp necrosis with or without radiographically detectable periradicular/interradicular bone resorption were collected and 32 were analysed, with three individuals contributing two samples; these were MDA-amplified and analysed by Checkerboard DNA-DNA hybridization for levels of 83 bacterial taxa. Two outcome measures were used: the percentage of teeth colonized by each species and the mean proportion of each bacterial taxon present across all samples.

RESULTS

The mean amount of DNA in the samples prior to amplification was 5.2 (±4.7) ng and 6.1 (±2.3) μg after MDA. The mean number of species detected per sample was 19 (±4) (range: 3-66) to the nearest whole number. The most prevalent taxa were Prevotella intermedia (96.9%), Neisseria mucosa (65.6%), Prevotella nigrescens (56.2%) and Tannerella forsythia (56.2%). Aggregatibacter (Haemophilus) aphrophilus and Helicobacter pylori were not detected. P. intermedia (10%), Prevotella tannerae (7%) and Prevotella nigrescens (4.3%) presented the highest mean proportions of the target species averaged across the positive samples.

CONCLUSION

Root canals of infected deciduous teeth had a diverse bacterial population. Prevotella sp. were commonly found with P. intermedia, Prevotella tannerae and Prevotella nigrescens amongst the most prominent species detected.

Relationships between subgingival microbiota and GCF biomarkers in generalized aggressive periodontitis

AIM

To examine relationships between subgingival biofilm composition and levels of gingival crevicular fluid (GCF) cytokines in periodontal health and generalized aggressive periodontitis (GAP).

MATERIALS AND METHODS

Periodontal parameters were measured in 25 periodontally healthy and 31 GAP subjects. Subgingival plaque and GCF samples were obtained from 14 sites from each subject. Forty subgingival taxa were quantified using checkerboard DNA-DNA hybridization and the concentrations of eight GCF cytokines were measured using Luminex. Cluster analysis was used to define sites with similar subgingival microbiotas in each clinical group. Significance of differences in clinical, microbiological and immunological parameters among clusters was determined using the Kruskal-Wallis test.

RESULTS

GAP subjects had statistically significantly higher GCF levels of interleukin-1beta (IL-1beta) (p<0.001), granulocyte-macrophage colony-stimulating factor (GM-CSF) (p<0.01) and IL-1beta/IL-10 ratio (p<0.001) and higher proportions of Red and Orange complex species than periodontally healthy subjects. There were no statistically significant differences in the mean proportion of cytokines among clusters in the periodontally healthy subjects, while the ratio IL-1beta/IL-10 (p<0.05) differed significantly among clusters in the aggressive periodontitis group.

CONCLUSIONS

Different subgingival biofilm profiles are associated with distinct patterns of GCF cytokine expression. Aggressive periodontitis subjects were characterized by a higher IL-1beta/IL-10 ratio than periodontally healthy subjects, suggesting an imbalance between pro- and anti-inflammatory cytokines in aggressive periodontitis.

Factors affecting human supragingival biofilm composition. I. Plaque mass

BACKGROUND AND OBJECTIVE

Little is known about the factors that affect the microbial composition of supragingival biofilms. This study was designed to examine the relationship between total DNA probe counts of supragingival biofilm samples, clinical parameters and supragingival biofilm composition.

MATERIAL AND METHODS

Supragingival plaque samples were taken from 187 systemically healthy adult subjects (n = 4745 samples). All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The relationship between total DNA probe counts and microbial composition was examined by subsetting the data into 10 groups based on 10 percentile increments of the total DNA probe counts. Differences among groups in terms of species counts and proportions were sought, as well as relationships of total plaque DNA probe count and clinical parameters.

RESULTS

There was a wide distribution in mean total DNA probe counts among the 187 subjects. With increasing total plaque levels there was a change in the proportions of individual species and microbial complexes. 'Small plaques' were characterized by high proportions of species in the yellow, orange, purple and 'other' complexes; plaques of moderate mass were characterized by high proportions of Actinomyces and purple complex species, while 'large plaques' exhibited increased proportions of green and orange complex species. Measures of gingival inflammation, pocket depth and recession were significantly positively associated with total DNA probe counts. Increased plaque numbers were related to increased pocket depth irrespective of presence or absence of gingival inflammation.

CONCLUSION

The proportions of individual species and microbial complexes in supragingival biofilms are influenced by the total numbers of organisms in the biofilm.

Application of the checkerboard immunoblotting technique to the quantification of host biomarkers in gingival crevicular fluid

BACKGROUND

The aim of this study was to describe the development and validation of the checkerboard immunoblotting (CBIB) technique for the high-throughput quantification of multiple inflammatory mediators in gingival crevicular fluid (GCF) samples.

METHODS

Monoclonal antibodies were used to bind GCF interleukin (IL)-1beta and -8 and matrix metalloproteinase (MMP)-8 to the surface of membranes. Biotinylated antibodies were used to detect bound antigens in a checkerboard format. Signals were developed using chemiluminescence, captured on film, and quantified using software for array analysis. The assay was tested for potential cross-reactions among the three pairs of antibodies. Eleven CBIBs were processed to determine the analytical sensitivity of the assay. Forty GCF samples were analyzed using CBIB and enzyme-linked immunosorbent assay (ELISA) in parallel, and the significance of the correlations among the results was tested using the Pearson correlation coefficient. Nine hundred thirty-one GCF samples were collected from 20 periodontally healthy subjects and 20 periodontitis subjects and analyzed using CBIB to test the assay's sensitivity and dynamic ranges using clinical samples.

RESULTS

The CBIB was capable of distinguishing among the three analytes. The sensitivity and dynamic ranges of the assay were suitable for the detection of the three targets in the majority of GCF samples. There were highly statistically significant (P <0.0001) positive correlations between CBIB and ELISA data for all three biomarkers. The periodontitis subjects had statistically significantly higher mean levels of IL-1beta and -8 compared to healthy subjects.

CONCLUSION

The CBIB technique is a sensitive and specific assay for the high-throughput quantification of MMP-8 and IL-8 and -1beta in GCF.

Salivary cytokine levels in subjects with chronic periodontitis and in periodontally healthy individuals: a cross-sectional study

BACKGROUND AND OBJECTIVE

Saliva has been proposed as a noninvasive diagnostic fluid that could be used in the diagnosis of oral and systemic diseases. The levels of salivary biomarkers, such as cytokines, could potentially be used as a surrogate to distinguish periodontally healthy individuals from subjects with periodontitis. Therefore, the goal of the present investigation was to determine if the levels of 10 different cytokines in saliva differed between a group of periodontally healthy individuals and a group of subjects with periodontitis. Correlations between the concentrations of these 10 cytokines and clinical parameters of periodontal disease were also examined.

MATERIAL AND METHODS

In this cross-sectional study, 74 subjects with chronic periodontitis and 44 periodontally healthy individuals were periodontally examined and had the levels of granulocyte-macrophage colony-stimulating factor, interleukin-1beta, interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-8, interleukin-10, interferon-gamma and tumor necrosis factor-alpha measured in whole saliva using a multiplexed bead immunoassay (Luminex). Significance of statistical differences in the levels of salivary cytokines between groups was determined using nonparametric analysis of covariance, adjusting for age and smoking status. The Spearman rank correlation coefficient was used to explore associations between the mean levels of salivary cytokines and mean clinical parameters.

RESULTS

There were no statistically significant differences between groups for any of the cytokines. There were weak, statistically significant positive associations between salivary interleukin-8 and pocket depth (r(s) = 0.2, p < 0.05) and bleeding on probing (r(s) = 0.2, p < 0.05), and weak negative correlations between salivary interleukin-10 and attachment level (r(s) = -0.2, p < 0.05) and bleeding on probing (r(s) = -0.3, p < 0.001).

CONCLUSION

Mean salivary levels of granulocyte-macrophage colony-stimulating factor, interleukin-1beta, interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-8, interleukin-10, interferon-gamma and tumor necrosis factor-alpha could not discriminate between periodontal health and disease.

Effect of herbal, essential oil, and chlorhexidine mouthrinses on the composition of the subgingival microbiota and clinical periodontal parameters

OBJECTIVE

The purpose of the present investigation was to determine if antimicrobial mouthrinses with different formulations could affect the composition of the subgingival microbiota and clinical parameters of adjacent tissues in periodontal maintenance subjects.

METHODS

One-hundred and sixteen subjects, who had been treated for chronic periodontitis and were in a maintenance program, were randomly assigned one of four mouthrinses, to be used twice daily for three months. The mouthrinses were herbal 1, herbal 2, essential oil, and chlorhexidine. Clinical measurements and subgingival plaque samples were taken at baseline and at three months. Plaque samples were individually evaluated for 18 test species/taxa using checkerboard DNA-DNA hybridization. Significance of differences between baseline and three months for both microbiological and clinical parameters were determined using the Wilcoxon Signed Ranks test. Significance of difference among groups for change in clinical and microbiological parameters was determined using analysis of covariance (ANCOVA), adjusting for baseline values.

RESULTS

Shifts in species proportions differed significantly for 9/18 test species/taxa among the four mouthrinse groups. Streptococcus and Capnocytophaga species were reduced most in the herbal rinse groups, while Veillonella parvula was reduced most in the essential oil and chlorhexidine groups. Actinomyces were also markedly reduced in the chlorhexidine group. Mean Plaque (PI) and Gingival Indices (GI) were reduced between baseline and three months in each group. Results emphasize that chlorhexidine (p < 0.001) and herbal (p < 0.05) rinses significantly reduced PI. Some subjects in each group responded better than others.

CONCLUSION

All four mouthrinses tested produced shifts in the composition of subgingival microbiota, although the results differed among the groups. The observed microbial changes were accompanied by improvements in clinical parameters in the periodontal maintenance subjects.

Factors affecting human supragingival biofilm composition. II. Tooth position

BACKGROUND AND OBJECTIVE

Little is known regarding the factors that affect the microbial composition of supragingival biofilms. This study was designed to test the hypothesis that tooth location affects the microbial composition of supragingival plaque beyond the effect due to plaque mass as reflected by total DNA probe count.

MATERIAL AND METHODS

Supragingival plaque samples were taken from the mesiobuccal aspect of each tooth in 187 subjects (n = 4745 samples). All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. Significance of differences in mean species counts and proportions were determined among tooth surfaces and six tooth type categories: molars, bicuspids, incisors/canines in the mandible and maxilla separately using the Kruskal-Wallis test. Stepwise multiple linear regression was employed to examine the relationship between species proportions and total DNA probe count, tooth location, periodontal and smoking status, age and sex.

RESULTS

All species differed significantly among tooth types and among the six tooth categories. Higher plaque levels were seen on molars and lower incisors. Some differences observed between tooth types could be partly explained by the level of plaque. Teeth with high plaque mass exhibited high levels of Capnocytophaga gingivalis, Actinomyces naeslundii genospecies 2, Campylobacter rectus and Campylobacter showae. However, certain species, such as Veillonella parvula and Streptococcus sanguinis, differed significantly at different tooth locations despite similarities in plaque mass. Twenty of the test species exhibited a significant association with tooth location after adjusting for total DNA probe count and subject level factors.

CONCLUSION

While plaque mass was associated with differences in proportions of many species in supragingival biofilms, tooth location also was strongly associated with species proportions in both univariate and multivariate analyses.

Clinical and Microbiologic Changes Associated With the Combined Use of a Powered Toothbrush and a Triclosan/Copolymer Dentifrice: A 3-Year Prospective Study

BACKGROUND

Different means are available for self-performed oral hygiene. The aim of this study was to evaluate the clinical and microbiologic effects of a preventive homecare program including the combined use of a powered toothbrush and a triclosan/copolymer-containing dentifrice.

METHODS

A total of 160 adult subjects without signs of destructive periodontal disease were recruited for this 3-year randomized controlled trial. The subjects were assigned to a homecare program using an oscillating/rotating powered toothbrush and a triclosan/copolymer/fluoride-containing dentifrice (test) or a manual toothbrush and a standard fluoride-containing dentifrice (control). Supragingival polishing and reinforcement of homecare procedures were provided every 6 months. Plaque, bleeding on probing (BOP), and probing depth (PD) were scored at baseline and after 1, 2, and 3 years. Subgingival plaque samples were taken from the mesial aspect of each tooth at baseline and after 1, 2, and 3 years and were analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. All data analyses were based on "intention-to-treat" with the subject as the statistical unit.

RESULTS

Compared to baseline, no significant changes in clinical parameters were observed during the 3 years, except for a reduction in the mean PD at the 2- and 3-year follow-up examinations (P <0.05). No significant differences were found between the two groups with regard to plaque, BOP, or PD or in the mean counts of the 40 species at any time point.

CONCLUSION

The study failed to prove additional benefits of the combined use of a powered toothbrush and a triclosan/copolymer-containing dentifrice in adult subjects without signs of destructive periodontal disease.

Use of multiple-displacement amplification and checkerboard DNA-DNA hybridization to examine the microbiota of endodontic infections

Multiple-displacement amplification (MDA) has been used to uniformly amplify bacterial genomes present in small samples, providing abundant targets for molecular analysis. The purpose of this investigation was to combine MDA and checkerboard DNA-DNA hybridization to examine the microbiota of endodontic infections. Sixty-six samples were collected from teeth with endodontic infections. Nonamplified and amplified samples were analyzed by checkerboard DNA-DNA hybridization for levels and proportions of 77 bacterial taxa. Counts, percentages of DNA probe counts, and percentages of teeth colonized for each species in amplified and nonamplified samples were computed. Significance of differences for each species between amplified and nonamplified samples was sought with Wilcoxon signed-rank test and adjusted for multiple comparisons. The amount of DNA in the samples ranged from 6.80 (+/- 5.2) ng before to 6.26 (+/- 1.73) mug after MDA. Seventy of the 77 DNA probes hybridized with one or more of the nonamplified samples. All probes hybridized with at least one sample after amplification. Most commonly detected species at levels of >10(4) in both amplified and nonamplified samples were Prevotella tannerae and Acinetobacter baumannii at frequencies between 89 and 100% of samples. The mean number of species at counts of >10(4) in amplified samples was 51.2 +/- 2.2 and in nonamplified samples was 14.5 +/- 1.7. The endodontic microbiota was far more complex than previously shown, although microbial profiles at teeth with or without periradicular lesions did not differ significantly. Species commonly detected in endodontic samples included P. tannerae, Prevotella oris, and A. baumannii.

A three-year prospective study of adult subjects with gingivitis II: microbiological parameters

AIM

To investigate whether the clinical benefits obtained with a periodontal prevention programme in subjects with periodontal health or minimal disease were accompanied by beneficial changes in the subgingival microbiota.

MATERIAL AND METHODS

One hundred and twenty-four subjects completed the study. Subjects were clinically and microbiologically monitored at baseline, 1, 2 and 3 years. Subgingival plaque samples were taken from the mesiobuccal aspect of every tooth and were analysed for the levels of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples=13,477). The mean counts of each of the 40 test species were calculated for each subject at each time point. Significance of differences over time was sought using the Friedman test. p values were adjusted for multiple comparisons.

RESULTS

All clinical parameters, at the microbiologically sampled sites, improved over time. The clinical changes were accompanied by statistically significant decreases in the mean counts of 35 of the 40 test species. Major reductions occurred by year 2 for Actinomyces, Capnocytophaga, Campylobacter, Fusobacterium and Prevotella species. At year 3, there was a modest re-growth of the majority of the species.

CONCLUSIONS

The clinical improvements obtained through preventive measures were accompanied by a shift to a more host-compatible subgingival microbiota.

Association of Eubacterium nodatum and Treponema denticola with human periodontitis lesions

BACKGROUND

The purpose of the present investigation was to compare the levels, proportions and percentage of sites colonized by 40 bacterial species in subgingival plaque samples from periodontally healthy subjects and patients with chronic periodontitis to seek possible pathogens other than the consensus pathogens Porphyromonas gingivalis and Tannerella forsythia.

METHOD

Subgingival plaque samples were taken from the mesial aspect of each tooth in 635 subjects with chronic periodontitis and 189 periodontally healthy subjects. The samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples = 21,832). Mean counts, % DNA probe counts and percentage of sites colonized at >10(5) were determined for each species in each subject and then averaged in each clinical group. Significance of difference between groups was determined using the Mann-Whitney test. Association between combinations of species and periodontal status was examined by stepwise logistic regression analysis. Analyses were repeated using a subset of subjects from both clinical groups who had proportions of P. gingivalis plus T. forsythia less than the median (4.42%) found in periodontally healthy subjects. All analyses were adjusted for multiple comparisons.

RESULTS

For the 824 subjects the consensus pathogens P. gingivalis and T. forsythia as well as Eubacterium nodatum and Treponema denticola had significantly higher mean counts, proportions and percentage of sites colonized in samples from subjects with periodontitis than from periodontally healthy subjects. There were significantly more Capnocytophaga gingivalis, Streptococcus gordonii and Veillonella parvula in periodontally healthy subjects. E. nodatum, T. denticola, Streptococcus oralis, Streptococcus intermedius, Fusobacterium nucleatum ssp. vincentii all had higher counts and proportions in diseased than healthy subjects who had low proportions of P. gingivalis and T. forsythia. Logistic regression analysis indicated that the same species groups were associated with disease status after adjusting for the proportions of the other species.

CONCLUSIONS

This investigation confirmed the strong association of P. gingivalis and T. forsythia with chronic periodontitis and emphasized a strong association of E. nodatum and T. denticola with periodontitis whether in the presence or absence of high levels of the consensus pathogens. Other species, including S. oralis, Eikenella corrodens, S. intermedius and F. nucleatum ssp. vincentii, were associated with disease when P. gingivalis and T. forsythia were present in low proportions.

Salivary IgA to cariogenic bacteria in HIV-positive children and its correlation with caries prevalence and levels of cariogenic microorganisms

The interrelationship of HIV infection, dental caries and mucosal immune responses remains controversial. In our study population of 40 HIV-infected and 40 healthy control children (ages 2-5 years) there was a significantly higher prevalence of dental caries in HIV-infected children (P<0.05). The extent of caries correlated with the severity of HIV disease. To determine whether the immunosuppression that ensues after HIV infection could contribute to the increased caries prevalence, the concentrations of total IgA and IgA specific to cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus) were determined in whole saliva by enzyme-linked immunosorbent assay. Levels of the same bacteria were also quantified in saliva using checkerboard DNA-DNA hybridization. A significantly increased level of total salivary IgA was found in the HIV-positive population (P < 0.05), but there were comparable titers of specific IgA to cariogenic bacteria in HIV-positive and healthy controls. The microbiological assessment also demonstrated similar levels of cariogenic microorganisms in both groups. We conclude that HIV-positive children appear to maintain the capacity to mount a mucosal immune response to cariogenic microorganisms, at least until late stages of disease.

Subgingival microbiota of Brazilian subjects with untreated chronic periodontitis

BACKGROUND

Different periodontopathogenic microbiota have been associated with periodontal diseases in several populations. The present investigation determined the subgingival microbiota of untreated chronic periodontitis Brazilians using the checkerboard DNA-DNA hybridization technique.

METHODS

Twenty-five periodontitis patients (mean age, 41 +/- 2; mean probing depth [PD], 3.3 +/- 0.2; mean attachment level [AL], 3.6 +/- 0.2) with no history of previous periodontal therapy and a control group of 14 healthy subjects (mean age, 34 +/- 0.6; mean PD, 1.8 +/- 0.2; mean AL, 1.7 +/- 0.1) were selected. Measurements of PD, AL, bleeding on probing, plaque accumulation, and suppuration were recorded at 6 sites/tooth. Subgingival plaque samples were obtained from 4 sites in each tooth/subject in both groups. The presence and levels of 41 subgingival species were determined in 4,032 plaque samples using whole genomic DNA probes and the checkerboard method.

RESULTS

Periodontal pathogens, as well as some unusual species (E. faecalis, E. coli and Bartonella sp.), were detected significantly more often and/or in higher levels in the periodontitis group (P < 0.05). Most species were more frequently detected in interproximal sites. B. forsythus, P. gingivalis, E. nodatum, and F. nucleatum ss vincentii showed a significant positive correlation with mean PD and AL (P < 0.05).

CONCLUSIONS

The subgingival microbiota of Brazilians with untreated chronic periodontitis were complex, including high proportions of periodontopathogens commonly found in other populations, as well as some unusual species.