Discovery, validation, and diagnostic ability of multiple protein-based biomarkers in saliva and gingival crevicular fluid to distinguish between health and periodontal diseases.

AIM: To discover and validate differential protein biomarker expression in saliva and gingival crevicular fluid (GCF) to discriminate objectively between periodontal health and plaque-induced periodontal disease states. MATERIALS AND METHODS: One-hundred and ninety participants were recruited from two centres (Birmingham and Newcastle upon Tyne, UK) comprising healthy, gingivitis, periodontitis, and edentulous donors. Samples from the Birmingham cohort were analysed by quantitative mass spectrometry proteomics for biomarker discovery. Shortlisted candidate proteins were then verified by enzyme-linked immunosorbent assay in both cohorts. Leave-one-out cross validation logistic regression analysis was used to identify the best performing biomarker panels. RESULTS: Ninety-five proteins were identified in both GCF and saliva samples, and 15 candidate proteins were selected based upon differences discovered between the donor groups. The best performing panels to distinguish between: health or gingivitis and periodontitis contained matrix metalloproteinase-9 (MMP9), S100A8, alpha-1-acid glycoprotein (A1AGP), pyruvate kinase, and age (area under the curve [AUC] 0.970); health and gingivitis contained MMP9, S100A8, A1AGP, and pyruvate kinase, but not age (AUC 0.768); and mild to moderate and advanced periodontitis contained MMP9, S100A8, A1AGP, pyruvate kinase, and age (AUC 0.789). CONCLUSIONS: Biomarker panels containing four proteins with and without age as a further parameter can distinguish between periodontal health and disease states.

Treatment of periodontitis reduces systemic inflammation in type 2 diabetes.

AIMS: To assess the impact of periodontal treatment on systemic inflammation in type 2 diabetes. MATERIALS AND METHODS: Adults with type 2 diabetes (n = 83) and without diabetes (controls, n = 75) were recruited, and participants with periodontitis received periodontal treatment and 12 months' follow-up. Biomarkers for periodontal inflammation (gingival crevicular fluid interleukin-6, tumour necrosis factor-α, interleukin-1ß, interferon-γ, matrix metalloproteinase-8, matrix metalloproteinase-9, adiponectin) and serum markers of inflammation and diabetes control (glycated haemoglobin, high sensitivity C-reactive protein, interleukin-6, tumour necrosis factor-α, interleukin-1ß, interferon-γ, leptin, adiponectin) were measured. Structural equation modelling was used to evaluate periodontal treatment effects on oral and systemic inflammation. RESULTS: Periodontal treatment resulted in significant improvements in clinical status and reductions in gingival crevicular fluid biomarkers from baseline to month 12. Structural equation modelling identified that, at baseline, individuals with diabetes and periodontitis had significantly higher systemic inflammation than non-diabetic controls with periodontitis (Δ = 0.20, p = .002), with no significant differences between groups for oral inflammation. There was a greater reduction in systemic inflammation following periodontal treatment in individuals with diabetes and periodontitis compared to those with periodontitis but not diabetes (Δ = -0.25, p = .01). CONCLUSIONS: Diabetes and periodontitis together appear to increase systemic inflammation, with evidence of reductions following periodontal treatment.

Fluid-driven interfacial instabilities and turbulence in bacterial biofilms.

Biofilms are thin layers of bacteria embedded within a slime matrix that live on surfaces. They are ubiquitous in nature and responsible for many medical and dental infections, industrial fouling and are also evident in ancient fossils. A biofilm structure is shaped by growth, detachment and response to mechanical forces acting on them. The main contribution to biofilm versatility in response to physical forces is the matrix that provides a platform for the bacteria to grow. The interaction between biofilm structure and hydrodynamics remains a fundamental question concerning biofilm dynamics. Here, we document the appearance of ripples and wrinkles in biofilms grown from three species of bacteria when subjected to high-velocity fluid flows. Linear stability analysis suggested that the ripples were Kelvin-Helmholtz Instabilities. The analysis also predicted a strong dependence of the instability formation on biofilm viscosity explaining the different surface corrugations observed. Turbulence through Kelvin-Helmholtz instabilities occurring at the interface demonstrated that the biofilm flows like a viscous liquid under high flow velocities applied within milliseconds. Biofilm fluid-like behavior may have important implications for our understanding of how fluid flow influences biofilm biology since turbulence will likely disrupt metabolite and signal gradients as well as community stratification.

Historical and contemporary hypotheses on the development of oral diseases: are we there yet?

Dental plaque is an oral biofilm that much like the rest of our microbiome has a role in health and disease. Specifically, it is the cause of very common oral diseases such as caries, gingivitis, and periodontitis. The ideas about oral disease development have evolved over time. In the nineteenth century, scientists could not identify bacteria related to disease due to the lack of technology. This led to the "Non-Specific Plaque Hypothesis" or the idea that the accumulation of dental plaque was responsible for oral disease without discriminating between the levels of virulence of bacteria. In the twentieth century this idea evolved with the techniques to analyze the changes from health to disease. The first common hypothesis was the "Specific Plaque Hypothesis" (1976) proposing that only a few species of the total microflora are actively involved in disease. Secondly, the "Non-Specific Plaque Hypothesis" was updated (1986) and the idea that the overall activity of the total microflora could lead to disease, was enriched by taking into account difference in virulence among bacteria. Then, a hypothesis was considered that combines key concepts of the earlier two hypotheses: the "Ecological Plaque Hypothesis" (1994), which proposes that disease is the result of an imbalance in the microflora by ecological stress resulting in an enrichment of certain disease-related micro-organisms. Finally, the recent "Keystone-Pathogen Hypothesis" (2012) proposes that certain low-abundance microbial pathogens can cause inflammatory disease by interfering with the host immune system and remodeling the microbiota. In this comprehensive review, we describe how these different hypotheses, and the ideas around them, arose and test their current applicability to the understanding of the development of oral disease. Finally, we conclude that an all-encompassing ecological hypothesis explaining the shifts from health to disease is still lacking.

Smoking decreases structural and functional resilience in the subgingival ecosystem.

AIMS: Dysbiotic microbial communities underlie the aetiology of several oral diseases, especially in smokers. The ability of an ecosystem to rebound from the dysbiotic state and re-establish a health-compatible community, a characteristic known as resilience, plays an important role in susceptibility to future disease. The present investigation was undertaken to examine the effects of smoking on colonization dynamics and resilience in marginal and subgingival biofilms. MATERIALS AND METHODS: Marginal and subgingival plaque and gingival crevicular fluid samples were collected from 25 current and 25 never smokers with pre-existing gingivitis at baseline, following resolution, after 1, 2 4, 7, 14 and 21 days of undisturbed plaque formation and following resolution. 16S cloning and sequencing was used for bacterial identification and multiplexed bead-based flow cytometry was used to quantify the levels of 27 immune mediators. RESULTS: Smokers demonstrated an early pathogenic colonization that led to sustained pathogen enrichment with periodontal and respiratory pathogens, eliciting a florid immune response. Smokers also demonstrated greater abundance of pathogenic species, poor compositional correlation between marginal and subgingival ecosystems, and significantly greater pro-inflammatory responses following resolution of the second episode of disease. CONCLUSIONS: The ability of the subgingival microbiome to "reset" itself following episodes of disease is decreased in smokers, thereby lowering the resilience of the ecosystem and decreasing its resistance to future disease.

Clinical and subclinical effects of power brushing following experimental induction of biofilm overgrowth in subjects representing a spectrum of periodontal disease.

AIM: Investigate short-term effects of power brushing following experimental induction of biofilm overgrowth in periodontal disease states. MATERIALS AND METHODS: Overall, 175 subjects representing each of five biofilm-gingival interface (BGI) periodontal groups were enrolled in a single-blind, randomized study. After stent-induced biofilm overgrowth for 21 days subjects received either a manual or a power toothbrush to use during a 4 weeks resolution phase. At baseline and during induction and resolution, standard clinical parameters were measured. Subclinical parameters included multikine analysis of 13 salivary biomarkers and 16s Human Oral Microbe Identification Microarray (HOMIM) probe analysis of subgingival plaque samples. RESULTS: All groups exhibited significantly greater reductions in bleeding on probing (BOP) (p = 0.002), gingival index (GI) (p = 0.0007), pocket depth (PD) (p = 0.04) and plaque index (p = 0.001) with power brushing compared to manual. When BGI groups were combined to form a shallow PD (PD ≤ 3 mm) and a deep PD group (PD > 4 mm) power brushing reduced BOP and GI in subjects with both pocket depths. Power brushing significantly reduced IL-1ß levels at resolution while changes in bacterial levels showed non-significant trends between both brushing modalities. CONCLUSIONS: Short-term changes in select clinical parameters and subclinical salivary biomarkers may be useful in assessing efficacy of power brushing interventions in a spectrum of periodontal disease states.

Host-bacterial interactions during induction and resolution of experimental gingivitis in current smokers.

BACKGROUND: Changes in clinical profiles, microbial succession, and immune mediator fluctuations have all been separately examined during onset and resolution of experimental gingivitis in smokers. However, because both the bacterial challenge and the host response contribute to periodontal disease, the purpose of this investigation is to simultaneously examine clinical, bacterial, and immune changes that occur during the onset and resolution of disease in smokers. METHODS: Experimental gingivitis was induced in 15 smokers for 21 days, followed by treatment with a sonic toothbrush for 21 days. Marginal and subgingival plaque and gingival crevicular fluid samples were collected at baseline; after 7, 14, and 21 days of undisturbed plaque formation; and 21 days after reinstitution of brushing. 16S cloning and sequencing was used for bacterial quantification, and multiplexed bead-based flow cytometry was used to quantify the levels of 27 immune mediators. RESULTS: Onset of clinical gingivitis was preceded by significant changes in the marginal and subgingival biofilms, with a decrease in the abundance of early colonizers, namely, Streptococcus, Veillonella, and Pseudomonas, and an increase in levels of periodontopathogens, such as Treponema, Selenomonas, Parvimonas, Dialister, and Campylobacter. This was accompanied by a decrease in anti-inflammatory, chemokine, and T-helper 2 (Th2) responses and altered Th1/Th2 ratios. Although the bacterial communities continued to shift in the same direction after onset of clinical gingivitis and returned to baseline levels after resolution of disease, the anti-inflammatory, chemokine, and Th2 profiles demonstrated an increase from day 14 that continued even after clinical health was evident. CONCLUSION: Both marginal and subgingival biofilms in smokers are characterized by early acquisition of pathogenic organisms, which elicit a sustained host response that persists even after removal of the bacterial challenge.

Tobacco smoking affects bacterial acquisition and colonization in oral biofilms.

Recent evidence suggests that smoking affects the composition of the disease-associated subgingival biofilm, yet little is known about its effects during the formation of this biofilm. The present investigation was undertaken to examine the contributions of smoking to the composition and proinflammatory characteristics of the biofilm during de novo plaque formation. Marginal and subgingival plaque and gingival crevicular fluid samples were collected from 15 current smokers and from 15 individuals who had never smoked (nonsmokers) following 1, 2, 4, and 7 days of undisturbed plaque formation. 16S rRNA gene cloning and sequencing were used for bacterial identification, and multiplex bead-based flow cytometry was used to quantify the levels of 27 immune mediators. Smokers demonstrated a highly diverse, relatively unstable initial colonization of both marginal and subgingival biofilms, with lower niche saturation than that seen in nonsmokers. Periodontal pathogens belonging to the genera Fusobacterium, Cardiobacterium, Synergistes, and Selenomonas, as well as respiratory pathogens belonging to the genera Haemophilus and Pseudomonas, colonized the early biofilms of smokers and continued to persist over the observation period, suggesting that smoking favors early acquisition and colonization of pathogens in oral biofilms. Smokers also demonstrated an early proinflammatory response to this colonization, which persisted over 7 days. Further, a positive correlation between proinflammatory cytokine levels and commensal bacteria was observed in smokers but not in nonsmokers. Taken together, the data suggest that smoking influences both the composition of the nascent biofilm and the host response to this colonization.

Changes in gingival crevicular fluid inflammatory mediator levels during the induction and resolution of experimental gingivitis in humans.

AIM: The goal of this study is to characterize the changes in 33 biomarkers within the gingival crevicular fluid during the 3-week induction and 4-week resolution of stent-induced, biofilm overgrowth mediated, experimental gingivitis in humans. METHODS: Experimental gingivitis was induced in 25 subjects for 21 days followed by treatment with a sonic powered toothbrush for 28 days. Clinical indices and gingival crevicular fluids were collected weekly during induction and biweekly during resolution. Samples were analysed using a bead-based multiplexing analysis for the simultaneous measurements of 33 biomarkers within each sample including cytokines, matrix-metalloproteinases (MMPs) and adipokines. Prostaglandin-E(2) was measured by enzyme-linked immunoadsorbant assay. Statistical testing using general linear models with structured covariance matrices were performed to compare stent to contralateral (non-stent) changes in clinical signs and in biomarker levels over time. RESULTS: Gingivitis induction was associated with a significant 2.6-fold increase in interleukin 1-beta (IL-beta), a 3.1-fold increase in IL-1alpha and a significant decrease in multiple chemokines as well as MMPs-1, -3 and 13. All changes in clinical signs and mediators rebounded to baseline in response to treatment in the resolution phase. CONCLUSIONS: Stent-induced gingivitis is associated with marked, but reversible increases in IL-alphaa and IL-1beta with suppression of multiple chemokines as well as selected MMPs.

The impact of powered and manual toothbrushing on incipient gingival recession.

AIM: To compare clinical effects of manual and powered toothbrushes on sites of localized gingival recession over 12 months. To evaluate patterns and the extent of toothbrush bristle wear. METHODS: A longitudinal, single-blind, randomized, parallel group clinical trial compared the effects of one manual and one powered toothbrush on incipient lesions of localized gingival recession. Toothbrush wear was evaluated concurrently by wear index and wear rating. RESULTS: Sixty patients were recruited and randomized to two groups with 52 (26 per group) attending the final visit at month 12. There were no differences between groups for full-mouth plaque index, pocket depth or bleeding on probing at baseline and month 12. There were no differences at target sites for clinical attachment level, pocket depth, bleeding on probing, plaque index, width of keratinized gingiva or maximal height of recession. There were no differences between the wear of the brushes as measured by wear index or wear rating. CONCLUSION: There was no progression of gingival recession in subjects using either toothbrush over 12 months. There was no difference in the overall wear of the powered and manual toothbrushes over successive 3-month periods.

Total protein concentration and total bacterial load as measures of residual interproximal plaque in comparative clinical trials.

AIM: Establish total protein concentration and total bacterial load as quantitative measures of residual interproximal plaque (IPP) in a clinical model designed to evaluate oral hygiene interventions. MATERIAL AND METHODS: This clinical model was a randomized, examiner and laboratory technician-blinded, parallel-design study whereby levels of residual IPP were compared for subjects using a manual toothbrush or a toothbrush+floss. Differences between interventions were compared after 7 and 21 days of use. Protein concentration was measured using 3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde in a fluorescence microplate format and bacterial load was assessed by quantitative real-time PCR with universal primers specific for 16S rRNA and detected by SYBR Green. ancova was used to assess the statistical significance of the differences between interventions while clinical relevance was evaluated by a statistical model described by Man-Son-Hing et al. 2002. RESULTS: Ninety-three subjects completed the study. Significant differences between interventions, using both outcome measures, were observed after 7 and 21 days. The difference between interventions by total protein concentration were further determined to be clinically relevant. CONCLUSIONS: Only total protein concentration provided both statistically significant and clinically relevant differences between two clinically distinct oral hygiene interventions in this clinical model for evaluating IPP.

Effect of manual and powered toothbrushes on orthodontic bracket bond strength.

PURPOSE: To assess in vitro the effect of manual and powered toothbrushes on the bond strength of orthodontic brackets. METHODS: Specimens of orthodontic brackets bonded to the surfaces of extracted teeth were exposed to one of two powered toothbrushes (Sonicare Elite, Braun Oral-B 3D Excel) or a manual toothbrush (Oral-B 35) for the equivalent of a 2-year exposure to brushing in the presence of toothpaste slurry. Control specimens underwent no brushing. For each treatment, 10 specimens were tested and evaluated. Shear bond strength of the orthodontic bracket to the tooth surface was assessed after exposure to simulated brushing. ANOVA was used to analyze the data. RESULTS: No differences in orthodontic bracket bond strength were observed between any of the three treatments and the control. The evaluated toothbrushes did not adversely affect the in vitro bonding strength of orthodontic brackets, suggesting they are safe to use in orthodontic patients.