Periodontal Disease Microbiology
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Questions and Answers

Which of the following describes the composition of dental plaque?

  • A protective layer that prevents the growth of bacteria
  • A community of microorganisms, including both Gram-positive and Gram-negative bacteria (correct)
  • A layer of mucus that traps food debris
  • A single species of bacteria that is always present in the mouth

    • Which of the following is NOT a characteristic of a biofilm?

  • It contains fluid channels
  • It can only grow on teeth (correct)
  • It is a community of interdependent organisms
  • It has an extra-cellular slime layer

    • What type of bacteria is primarily found subgingivally?

  • Gram-positive bacteria
  • Gram-negative bacteria
  • Both Gram-positive and Gram-negative bacteria (correct)
  • Facultative anaerobic bacteria

    • What is the function of the extra-cellular slime layer in a biofilm?

    <p>To protect the bacteria from the host's immune system (A)</p> Signup and view all the answers

    What is meant by a dynamic equilibrium between dental plaque and the host defenses?

    <p>There is a constant balance between the growth of dental plaque and the host's immune response (D)</p> Signup and view all the answers

    What is the primary aim of the 'Periodontal Disease Microbiology' module, as outlined in the provided content?

    <p>To understand the role of microbial components in the development of periodontal disease. (A)</p> Signup and view all the answers

    Which of the following learning outcomes is NOT explicitly mentioned for this session?

    <p>Analyzing the impact of periodontal disease on overall health. (B)</p> Signup and view all the answers

    Based on the intended learning outcomes, which aspect of periodontal disease is NOT the primary focus of this session?

    <p>The clinical management of periodontal disease. (B)</p> Signup and view all the answers

    What type of assessment is used to evaluate the student's understanding of the material discussed in this session?

    <p>A combination of formative and summative. (A)</p> Signup and view all the answers

    Which of the following subjects is NOT listed as a pre-session knowledge requirement for this session?

    <p>Dental anatomy. (C)</p> Signup and view all the answers

    Which of these topics is NOT directly mentioned in the 'Recall' section of the content?

    <p>The specific types of bacteria found in the oral cavity. (B)</p> Signup and view all the answers

    The GDC Learning Outcomes mentioned in this content specifically relate to which aspect of dental practice?

    <p>The understanding of the transmission of infectious agents within the dental setting. (D)</p> Signup and view all the answers

    What is the primary focus of the ‘Recall’ section in this content?

    <p>Refreshing the student's knowledge of basic concepts related to the topic. (D)</p> Signup and view all the answers

    Which of the following is a characteristic of Porphyromonas gingivalis?

    <p>Gram-positive bacillus (D)</p> Signup and view all the answers

    What is a key function of the gingipains produced by Porphyromonas gingivalis?

    <p>To utilize gingival crevicular fluid as a nutrient source (D)</p> Signup and view all the answers

    What is the role of fimbriae in bacterial pathogenesis?

    <p>They enhance the bacterial attachment to host tissues (A)</p> Signup and view all the answers

    Which of the following is a characteristic of Tannerella forsythia?

    <p>Difficult to culture (C)</p> Signup and view all the answers

    How do Porphyromonas gingivalis haemagglutins and platelet aggregators contribute to disease?

    <p>They can potentially contribute to heart disease (A)</p> Signup and view all the answers

    What is the significance of the prtH phenotype in Tannerella forsythia?

    <p>It is associated with an increased risk of periodontal disease (B)</p> Signup and view all the answers

    What is a major mechanism by which Porphyromonas gingivalis can evade the host's immune system?

    <p>Suppression of the early polymorphonuclear leukocyte (PMN) response (B)</p> Signup and view all the answers

    What is a key function of Porphyromonas gingivalis's carbohydrate capsule?

    <p>To resist certain host defenses (A)</p> Signup and view all the answers

    Which of the following is a hallmark of the Non-Specific Plaque Hypothesis?

    <p>The presence of any large amount of bacteria in the gingival sulcus will result in periodontal disease. (A)</p> Signup and view all the answers

    What is a major criticism of the Non-Specific Plaque Hypothesis?

    <p>It does not adequately explain why some patients with minimal plaque experience severe periodontal disease. (A)</p> Signup and view all the answers

    According to the Specific Plaque Hypothesis, as periodontal disease progresses, there is a shift in the oral microbiota from:

    <p>Beneficial microbes to pathogenic microbes. (A)</p> Signup and view all the answers

    The passage mentions that bacteria involved in periodontal disease can perform which of the following actions?

    <p>All of the above. (D)</p> Signup and view all the answers

    Which of the following is NOT a hypothesis mentioned in the content that attempts to explain the role of bacteria in periodontal disease?

    <p>The Proteolytic Plaque Hypothesis. (D)</p> Signup and view all the answers

    Which hypothesis emphasizes the crucial role of microbial dysbiosis and shifts in bacterial populations in periodontal disease?

    <p>Specific Plaque Hypothesis (C)</p> Signup and view all the answers

    Which hypothesis emphasizes the complex interplay between the host's immune response and the bacterial community in periodontal disease?

    <p>Both C and D. (A)</p> Signup and view all the answers

    What is a potential limitation of the Keystone Pathogen- Host Response Hypothesis?

    <p>It may be difficult to identify and target a single keystone pathogen for therapeutic interventions. (C)</p> Signup and view all the answers

    What does the keystone pathogen-host response hypothesis suggest is the primary cause of periodontal tissue destruction?

    <p>An uncontrolled host inflammatory response triggered by keystone species (D)</p> Signup and view all the answers

    What is the primary factor that determines whether gingivitis will progress to periodontitis?

    <p>An unknown factor that disrupts the delicate balance between the biofilm and the host (C)</p> Signup and view all the answers

    What is the role of keystone species in the biofilm, according to the keystone pathogen-host response hypothesis?

    <p>They trigger a shift towards a pathogenic biofilm community (B)</p> Signup and view all the answers

    What does the text suggest about the direct role of bacterial pathogens in periodontal destruction?

    <p>Bacterial pathogens are not directly responsible for periodontal destruction (C)</p> Signup and view all the answers

    What is the primary difference between the traditional view of periodontal disease and the keystone pathogen-host response hypothesis?

    <p>The traditional view suggests that bacteria are the sole cause of periodontal destruction (A)</p> Signup and view all the answers

    What is the likely outcome when a healthy biofilm community is disrupted by a keystone species?

    <p>The biofilm community shifts to a pathogenic profile (D)</p> Signup and view all the answers

    Which of the following statements is supported by the text?

    <p>Uncontrolled host inflammatory response is a key factor in periodontal tissue damage (B)</p> Signup and view all the answers

    What is the state of the biofilm microbiota in healthy individuals?

    <p>In a state of equilibrium, maintained by a balance of beneficial and potentially harmful microbes (B)</p> Signup and view all the answers

    Which of the following bacteria are considered major causative agents of periodontal disease according to Socransky's microbial complexes?

    <p>All of the above (D)</p> Signup and view all the answers

    Flashcards

    Oral Bacteria

    Over 700 species of microorganisms found in the mouth.

    Biofilm

    A community of inter-dependent organisms that stick to a surface, like dental plaque.

    Extracellular Slime Layer

    A protective layer in biofilms that helps organisms thrive and survive.

    Subgingival Microbes

    Microbes that exist below the gum line, some are loosely attached or free-floating.

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    Dynamic Equilibrium

    A balanced state between dental plaque and the host defenses in health and stable gingivitis.

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    Haem in bacteria

    Haem is released by Pg for nutrients and bacterial adherence.

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    Virulence factors

    Characteristics that enhance a bacterium's ability to invade tissues.

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    Pg tissue invasion

    Porphyromonas gingivalis can invade host cells, evading defenses.

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    Gram-negative bacillus

    A classification for bacteria like Porphyromonas gingivalis, characterized by a thin peptidoglycan layer.

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    GCF (Gingival Crevicular Fluid)

    Liquid found in the gum pocket, used by Pg for nutrients.

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    Fimbrae function

    Hair-like structures that aid bacterial adherence to cells.

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    Tannerella forsythia

    A Gram-negative, anaerobic bacterium linked to periodontitis.

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    LPS (Lipopolysaccharide)

    A component of the outer membrane of Gram-negative bacteria, playing a role in immune response.

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    Periodontal Disease

    A disease affecting the tissues surrounding the teeth, often linked to microbial activity.

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    Plaque Biofilm

    A dense layer of bacteria and extracellular substances that forms on tooth surfaces.

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    Host Immune Response

    The body's defense mechanism activated upon microbial invasion.

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    Microbial Transition

    The shift from a healthy microbial community to one that promotes periodontal disease.

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    Inflammation

    A biological response to harmful stimuli, often seen in periodontal disease.

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    Aetiology of Oral Disease

    The study of the causes and origins of oral diseases.

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    Transmission of Infectious Agents

    The ways in which pathogens spread in dental settings.

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    Porphyromonas gingivalis

    A key bacterium associated with causing periodontal disease.

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    Treponema denticola

    A bacterium involved in periodontal disease, identified in the red complex.

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    Socransky’s Microbial Complexes

    Color-coded groupings of bacteria based on their relationship to periodontal health.

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    Specific Plaque Hypothesis

    A theory suggesting specific bacteria are solely responsible for periodontal destruction, now disputed.

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    Periodontal Disease Factors

    Smoking, stress, and systemic diseases influence periodontal disease progression.

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    Gingivitis Progression

    Gingivitis does not become periodontitis without an unknown tipping factor.

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    Pathogenic Microbe Shift

    Shift from beneficial to pathogenic microbes triggers inflammation.

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    Biofilm Homeostasis

    Healthy biofilm microbiota maintains stability and equilibrium.

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    Immune Response Role

    The uncontrolled host inflammatory response leads to tissue destruction.

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    Keystone Pathogen Hypothesis

    Keystone species trigger shifts to dysbiotic biofilm, causing damage.

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    Current Research Findings

    No solid evidence links specific bacteria directly to periodontal destruction.

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    Host Inflammatory Response

    The body's uncontrolled response contributes significantly to periodontal tissue destruction.

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    Proteases

    Enzymes that break down proteins, including collagenase.

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    Non-specific Plaque Hypothesis

    Suggests that periodontal disease results from large bacterial masses in plaque.

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    Issues with Non-specific Plaque Hypothesis

    Points out that not all patients with plaque develop periodontitis.

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    Microbial Shift Hypothesis

    Suggests a change in oral microbiota from beneficial bacteria to harmful pathogens as disease progresses.

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    Ecological Plaque Hypothesis

    Focuses on the ecological balance of the oral microbiome in relation to periodontitis.

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    Study Notes

    Periodontal Disease Microbiology

    • Module: Oral and Dental Science

    • Tutor: Ms P Lazarou

    • Learning Outcomes (GDC):

      • Explain general and systemic disease and their relevance to oral health
      • Explain the aetiology and pathogenesis of oral disease
      • Explain the potential routes of transmission of infectious agents in dental practice

    • Aim: Gain knowledge of the microbial components found in periodontal disease and realise their role.

    • Intended Learning Outcomes:

      • Revise mechanisms in periodontal disease aetiology (plaque biofilm, host immune response, inflammation)
      • Recognise microbial organisms and discuss virulence factors in periodontal disease
      • Describe microbial transition from gingival health to periodontal disease
      • Discuss the bacteria's role in periodontal disease aetiology, referencing historical and current concepts

    • Assessment:

      • Formative: Forum discussion
      • Summative: Oral and Dental Sciences Eassessment questions

    • Pre-session Knowledge: Microbiology/Bacteria, Dental Plaque/Biofilm, Immunology, Virulence Factors, Inflammation.

    • Recall Points:

      • Dental Plaque/Biofilm: Definition, formation on tooth surfaces.
      • Immunology: Immune response to pathogens.
      • Virulence Factors: Virulence factors deployed by oral microorganisms.
      • Inflammation: Inflammatory process

    • Oral Bacteria:

      • Over 700+ species of oral microorganisms
      • Gram-positive, Gram-negative, Facultative, Anaerobic

    • Biofilm:

      • Community of interdependent organisms growing on a surface.
      • Dental plaque is a biofilm
      • Extracellular slime layer (protective layer)
      • Fluid channels in biofilm.
      • Different types of bacteria (early and late colonizers) found in biofilm

    • Periodontal Pathogens:

      • 12-15 types known to be particularly likely to cause periodontal breakdown.
      • Key examples: Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Aggregatibacter actinomycetemcomitans (with their virulence factors)

    • Virulence Factors:

      • Proteinases (gingipains) – digest tissue proteins for nutrients.
      • Endotoxins (lipopolysaccharide) – produced by Gram-negative organisms
      • Haemagglutination – produced by Gram-negative organisms, e.g., to adhere to host cells.

    • Fimbraie and Tissue Invasion:

      • Virulence factors aid binding and tissue invasion
      • Inside host cells, bacteria are safer from host defence, allowing replication
      • Porphyromonas gingivalis: Gram-negative, anaerobe, resists host defences. Crucial features: carbohydrate capsule, gingipains, LPS, haemaglutins, fimbraie, suppression of PMNs

    • Tannerella forsythia:

      • Gram-negative, anaerobic, fusiform bacteria
      • Difficult culture, specific phenotype (prtH) often in periodontitis
      • Produce proteases and factors that lead to cell death

    • Treponema denticola:

      • Uses GCF for energy and multiplication
      • Adherence factors, tissue invasion
      • Disrupts host defences via cytokines
      • Delays healing through interfering with PMN migration

    • Aggregatibacter actinomycetemcomitans:

      • Gram negative coccoid bacterium, virulent, not motile, or not anaerobic.
      • Virulence factors: Leukotoxins, other toxins
      • Damages fibroblasts and epithelial cells; has collagenase.
      • Invades host epithelial cells

    • Theories on the role of bacteria in Periodontal Disease:

      • Non-specific Plaque Hypothesis: Stagnant plaque, high bacteria leads to periodontal disease due to inflammation. Issues include simplifying, failing to account for specific site variations
      • Specific Plaque/Microbial Shift Hypothesis: As periodontal disease progresses, beneficial bacteria shift to specific pathogenic bacteria, like Gram-negative ones
      • Socransky's Microbial Complexes: Categorization of bacteria based on their interactions (orange/red –periodontal disease, yellow/green/blue/purple – associated with gingival health).
      • Ecological Plaque Hypothesis: Changes in the subgingival environment and triggers inflammatory responses, favoring pathogenic bacteria. Factors include GCF, pH, temperature oxygen decrease.
      • Microbial Homeostasis-Host Response Hypothesis: Pathogenic biofilm community triggers uncontrolled host responses, leading to damage. Biofilm stability is important.
      • Keystone Pathogen-Host Response Hypothesis: Keystone species in biofilm trigger a shift, uncontrolled host response and periodontal damage.

    • Aetiology of Periodontal Disease: Multifactorial including microbial factors, environmental factors (e.g., smoking, poor oral hygiene, existing pockets, plaque retentive factors, genetic factors, defects in PMN, inherited genotypic variants).

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    Periodontal Disease Microbiology PDF

    Description

    This quiz covers the essential microbial components associated with periodontal disease, focusing on their role in oral health and disease. Students will explore the aetiology and pathogenesis, including mechanisms such as plaque biofilm and host immune response. Gain insights into the microbial transition from gingival health to periodontal disease and discuss virulence factors involved.

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