Periodontal Disease Microbiology Module
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Questions and Answers

Which bacterial species is NOT motile?

  • Aggregatibacter actinomycetemcomitans (correct)
  • Tannerella forsythia
  • Treponema denticola
  • Porphyromonas gingivalis

    • Which bacterial species primarily relies on GCF for nutrition?

  • Aggregatibacter actinomycetemcomitans
  • Tannerella forsythia
  • Porphyromonas gingivalis (correct)
  • Treponema denticola

    • Which bacterium is associated with aggressive periodontitis?

  • Treponema denticola
  • Tannerella forsythia
  • Porphyromonas gingivalis
  • Aggregatibacter actinomycetemcomitans (correct)

    • Which virulence factor can help bacteria evade host defenses and replicate more effectively?

    <p>Tissue invasion (B)</p> Signup and view all the answers

    Which bacterial species is known to produce proteases and an apoptotic-inducing factor?

    <p>Tannerella forsythia (A)</p> Signup and view all the answers

    Which bacterial species possesses adherence factors that can bind to fibroblasts?

    <p>Treponema denticola (B)</p> Signup and view all the answers

    Which bacterium utilizes a carbohydrate capsule to resist host defenses?

    <p>Porphyromonas gingivalis (C)</p> Signup and view all the answers

    Which bacterial species is particularly difficult to culture in a laboratory setting?

    <p>Tannerella forsythia (A)</p> Signup and view all the answers

    What mechanism is primarily involved in the aetiology of periodontal disease?

    <p>Plaque biofilm formation (D)</p> Signup and view all the answers

    Which of the following is a common virulence factor deployed by oral microorganisms in periodontal disease?

    <p>Endotoxins (C)</p> Signup and view all the answers

    What is a significant transition seen in the microbial composition from gingival health to periodontal disease?

    <p>Increase in opportunistic pathogens (A)</p> Signup and view all the answers

    Which factor does NOT play a role in the host immune response to periodontal disease?

    <p>Formation of dental calculus (B)</p> Signup and view all the answers

    Which statement correctly describes the role of inflammation in periodontal disease?

    <p>It results in the destruction of periodontal tissues due to the immune response. (D)</p> Signup and view all the answers

    What is one consequence of the leukotoxin produced by Gram-negative coccoid bacillus?

    <p>Disrupts the host defenses (D)</p> Signup and view all the answers

    Which hypothesis suggests that all bacteria in plaque contribute equally to periodontal disease?

    <p>Non-specific Plaque Hypothesis (A)</p> Signup and view all the answers

    What is the key concept of the Specific Plaque Hypothesis?

    <p>Only specific pathogens are responsible for periodontal disease (B)</p> Signup and view all the answers

    According to the issues with the Non Specific Plaque Hypothesis, what observation is noted?

    <p>Patients with minimal biofilm can suffer from periodontitis (D)</p> Signup and view all the answers

    Which of the following bacteria are associated with periodontal diseases according to the Specific Plaque Hypothesis?

    <p>Tannerella forsythia (C)</p> Signup and view all the answers

    What does the Ecological Plaque Hypothesis emphasize?

    <p>Changes in the microbial community can drive disease (C)</p> Signup and view all the answers

    What role do proteases, such as collagenase, play in periodontal disease?

    <p>They are involved in the destruction of host tissues (A)</p> Signup and view all the answers

    What characterizes the Keystone Pathogen-Hypothesis?

    <p>Identifies specific pathogens that can shift the environment towards disease (C)</p> Signup and view all the answers

    What factor is common to both the initiation and progression of periodontal disease?

    <p>Smoking (B)</p> Signup and view all the answers

    Which hypothesis explains that specific bacteria are not the direct cause of periodontal destruction?

    <p>Keystone Pathogen-Host Response Hypothesis (D)</p> Signup and view all the answers

    What primarily triggers the shift from beneficial microbes to pathogenic ones in periodontal disease?

    <p>Shift to dysbiotic biofilm community (C)</p> Signup and view all the answers

    Which of the following is NOT considered an environmental factor related to periodontal disease?

    <p>Genetic polymorphisms (A)</p> Signup and view all the answers

    According to the discussed hypotheses, what is the primary cause of tissue destruction in periodontal disease?

    <p>Uncontrolled host inflammatory response (A)</p> Signup and view all the answers

    How does gingivitis progress to periodontitis according to Page and Schroeder?

    <p>With a shift in the biofilm-host balance (A)</p> Signup and view all the answers

    What is one of the primary roles of a healthy biofilm microbiota in periodontal health?

    <p>To maintain biological equilibrium (D)</p> Signup and view all the answers

    What type of factors contribute to the multifactorial aetiology of periodontal disease?

    <p>Environmental and host defense factors (C)</p> Signup and view all the answers

    What primarily characterizes a biofilm in the oral environment?

    <p>A community of inter-dependent organisms (A)</p> Signup and view all the answers

    Which statement about dental plaque is correct?

    <p>It is a type of biofilm that can contain free-floating microbes. (A)</p> Signup and view all the answers

    What contributes to the destabilization of the equilibrium in periodontal health?

    <p>Increase in pathogenicity of biofilm microorganisms (C)</p> Signup and view all the answers

    Which of the following is NOT a recognized periodontal pathogen?

    <p>Streptococcus pneumoniae (D)</p> Signup and view all the answers

    Which virulence factor do periodontal pathogens use to compromise host defenses?

    <p>Proteinases such as gingipains (C)</p> Signup and view all the answers

    What type of microbial species is primarily found in areas that are subgingival?

    <p>Both Gram-positive and Gram-negative bacteria (A)</p> Signup and view all the answers

    What is the role of the extracellular slime layer in a biofilm?

    <p>To protect the biofilm from environmental threats (A)</p> Signup and view all the answers

    What is the relationship between dental plaque and host defenses in health?

    <p>There exists a dynamic equilibrium between plaque and host defenses. (B)</p> Signup and view all the answers

    Which colour-coded complex is primarily associated with causing periodontal disease?

    <p>Orange/red (C)</p> Signup and view all the answers

    According to the contemporary theories, what triggers the host inflammatory response in the ecological plaque hypothesis?

    <p>Nonspecific bacteria in the subgingival environment (B)</p> Signup and view all the answers

    What factor contributes to the growth of pathogenic bacteria in the biofilm, according to the ecological plaque hypothesis?

    <p>Increased bleeding (D)</p> Signup and view all the answers

    What is a characteristic of the microbial homeostasis-host response hypothesis?

    <p>It emphasizes the role of the immune response to biofilms (C)</p> Signup and view all the answers

    What recent research finding challenges the specific plaque hypothesis?

    <p>700+ diverse oral microbes exist, complicating direct causation (C)</p> Signup and view all the answers

    Which of the following statements is supported by the ecological plaque hypothesis regarding GCF?

    <p>GCF changes lead to increased pathogen growth (A)</p> Signup and view all the answers

    What role does subgingival debridement play in oral health, according to the content?

    <p>It reduces the number of pathogens in the ecosystem (B)</p> Signup and view all the answers

    What is one key change in the environment that supports dysbiosis in the gingival sulcus?

    <p>Reduced pH levels (A)</p> Signup and view all the answers

    Flashcards

    Periodontal Disease

    A serious gum infection damaging soft tissue and bone supporting teeth.

    Plaque Biofilm

    A sticky film of bacteria that forms on teeth and can cause dental issues.

    Virulence Factors

    Molecules produced by pathogens that enable them to cause disease.

    Host Immune Response

    The body's defense mechanisms activated against pathogens invading the oral cavity.

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    Microbial Transition

    The change in bacterial composition from healthy gums to those affected by periodontal disease.

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    Oral Microorganisms

    700+ species found in the oral cavity, including Gram-positive and Gram-negative bacteria.

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    Biofilm

    A community of inter-dependent organisms that grow on surfaces, like dental plaque.

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    Dental Plaque

    A type of biofilm that forms on teeth, can contain both adherent and free-floating microbes.

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    Subgingival Microbes

    Bacteria found below the gum line, can be loose or free-floating.

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    Equilibrium in Gingivitis

    Dynamic balance between dental plaque and host defenses in healthy gums.

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    Periodontitis Disturbance

    Condition arising when the equilibrium of plaque and host defenses is disturbed.

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    Periodontal Pathogens

    12-15 specific bacteria linked to periodontal disease, such as Porphyromonas gingivalis.

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    Socransky's Complexes

    Microbial groups categorized by color, indicating their role in periodontal health.

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    Orange/Red Complex

    Microbes associated with major causes of periodontal disease.

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    Yellow/Green/Blue/Purple Complex

    Microbial groups compatible with healthy gums.

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    Specific Plaque Hypothesis Issues

    Challenges with the idea that certain plaque causes periodontal disease.

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    Ecological Plaque Hypothesis

    Theory stating that non-specific bacteria changes lead to increased pathogens.

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    Gingival Crevicular Fluid (GCF)

    Fluid in gums that changes microbial ecology and supports pathogen growth.

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    Microbial Homeostasis-Host Response Hypothesis

    Pathogenic biofilm triggers an immune response damaging periodontal tissues.

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    Dysbiosis

    Disruption of microbial balance leading to pathogenic growth in gums.

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    Periodontitis Progression

    Gingivitis advances to periodontitis due to unknown factors disrupting biofilm-host balance.

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    Host Inflammatory Response

    The body's aggressive reaction causing tissue destruction in periodontal disease.

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    Dysbiotic Biofilm

    A harmful shift in microbiota that disrupts balance and promotes periodontal disease.

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    Keystone Pathogen

    A species that triggers a shift to a harmful biofilm community affecting gum health.

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    Aetiology of Periodontal Disease

    The study of multiple factors leading to periodontal disease including microbes, environment, and host defense.

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    Environmental Factors

    Conditions like smoking and poor oral hygiene that contribute to periodontal disease risk.

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    Microbial Factors

    The role of microorganisms in initiating and worsening periodontal disease.

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    Host Defence Factors

    The body’s genetic and immune responses that influence susceptibility to periodontal disease.

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    Endotoxins

    Toxins produced by Gram-negative bacteria that can cause inflammation.

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    Porphyromonas gingivalis

    A Gram-negative, anaerobic bacillus linked to periodontal disease.

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    Fimbrae

    Hair-like structures that help bacteria adhere to host tissues.

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    Haemagglutination

    The clumping of red blood cells by bacteria to access nutrients.

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    Tannerella forsythia

    A Gram-negative anaerobic bacterium difficult to culture, linked to periodontitis.

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    Treponema denticola

    A motile bacterium that invades tissues and disrupts host defenses.

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    Aggregatibacter actinomycetemcomitans

    Bacterium associated with aggressive and refractory periodontitis.

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    Gram-negative Coccoid bacillus

    A short rod bacteria associated with virulence factors like leukotoxin that can kill white blood cells.

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    Leukotoxin

    A virulence factor that can kill white blood cells, disrupting host defenses.

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    Non-specific Plaque Hypothesis

    Suggests that periodontal disease occurs due to large, stagnant plaques causing inflammation and tissue destruction.

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    Issues with Non-specific Plaque Hypothesis

    This hypothesis is too simplistic as not all gingivitis progresses to periodontitis, and biofilm presence varies among patients.

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    Specific Plaque Hypothesis

    Proposes that periodontal disease arises from a shift in the oral microbiota from beneficial Gram-positive bacteria to harmful Gram-negative pathogens.

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    Socransky’s Microbial Complexes

    Refers to specific bacterial groups identified as associated with periodontal diseases.

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    Keystone Pathogen Hypothesis

    Suggests that certain pathogens can disrupt the balance of the microbiota, leading to periodontal disease.

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    Study Notes

    Periodontal Disease Microbiology

    • The module is Oral and Dental Science
    • The tutor is Ms P Lazarou
    • The aims of the session are to gain knowledge of microbial components in periodontal disease and understand their role.
    • Learning outcomes include reviewing mechanisms involved in periodontal disease aetiology (plaque biofilm and host immune response/inflammation).
    • Students should be able to recognise microbial organisms found in periodontal disease and discuss their virulence factors.
    • Students should also be able to describe the microbial transition from gingival health to periodontal disease.
    • Students should discuss bacteria's role in the aetiology of periodontal disease, referencing historical and current concepts.

    GDC Learning Outcomes

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

    Assessment

    • Formative: Forum discussion
    • Summative: Questions in Oral and Dental Sciences Eassessment
    • Microbiology/bacteria
    • Dental plaque/biofilm
    • Immunology
    • Virulence factors
    • Inflammation

    Recall

    • What is dental plaque/biofilm? How does it form on tooth surfaces?
    • Immunology: consider the immune response to pathogens
    • Virulence factors: virulence factors deployed by oral microorganisms
    • Inflammation: define the 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 biofilm; some subgingival microbes are loosely adherent.
    • Extracellular slime layer: protective layer, fluid channels

    Which Type Found Subgingivally?

    • Gram-positive or Gram-negative bacteria

    Health and Stable Gingivitis

    • Dynamic equilibrium between dental plaque and host defences in health and stable gingivitis
    • This equilibrium is disturbed in periodontitis.

    This may be due to:

    • Increased amount of plaque
    • Increase in pathogenicity of microorganisms in the biofilm
    • Compromised host defense

    Periodontal Pathogens and their Virulence Factors

    • 12-15 bacteria types associated with periodontal breakdown.

    Recognised Periodontal Pathogens

    • Porphyromonas gingivalis (Pg)
    • Tannerella forsythia (Tf)
    • Treponema denticola (Td)
    • Aggregatibacter actinomycetemcomitans (Aa)

    Virulence Factors

    • Proteinases: such as gingipains (digest tissue proteins for nutrient gain and host defence destruction).
    • Endotoxins/Lipopolysaccharide: produced by Gram-negative organisms.
    • Haemagglutination: of RBC by e.g., Pg (releases haem for nutrient and bacterial adhesion).
    • Exotoxins: such as vacuolating toxin.
    • Urease: neutralizes gastric acid (by ammonia).
    • Other factors: include fimbrae for tissue invasion and disrupting host defences.

    Fimbraie and Tissue Invasion

    • Virulence factors aid bacterial binding to epithelium, aiding tissue invasion (e.g., P. gingivalis).
    • Once the bacterium invades a host cell, it's safe from host defenses, allowing replication.

    Porphyromonas gingivalis

    • Gram-negative bacillus, anaerobe, non-saccharolytic, non-motile.
    • Carbohydrate capsule to resist host defenses.
    • Produces gingipains to use GCF as a nutrient source.
    • LPS (lipopolysaccharide).
    • Haemagglutins & platelet aggregators.
    • Fimbrae and tissue invasion.
    • Suppresses early PMN (polymorphonuclear leukocytes) response.

    Tannerella forsythia

    • Gram-negative, anaerobic, fusiform.
    • Difficult to culture.
    • A particular phenotype (prtH) more often in periodontitis than health.
    • Produces proteases and apoptotic-inducing factors (causing cell death).

    Treponema denticola

    • Uses GCF for energy and multiplication.
    • Adherence factors bind to fibroblasts.
    • Motile, invades tissue.
    • Disrupts host defenses by inducing and degrading cytokines.
    • Delays wound healing by inhibiting PMN migration.

    Aggregatibacter actinomycetemcomitans

    • Associated with aggressive periodontitis.
    • Not motile or anaerobic.
    • Gram-negative coccoid bacillus (short rod).
    • Leukotoxin, killing WBC and disrupting host defenses.
    • Destroys fibroblasts and epithelial cells.
    • Produces proteases, including collagenase.
    • Invades host epithelial cells.

    Role of bacteria in Periodontal Disease

    • Multifactorial: Microbial and non-microbial factors, severity of periodontitis and genetic factors.

    Theories on the role of bacteria in Periodontal Disease

    • 5 Hypotheses: Non-specific plaque, Specific plaque, Ecological plaque, Microbial homeostasis-host response, & Keystone pathogen-host response hypotheses.

    Non-Specific Plaque Hypothesis

    • Stagnation of plaque biofilm, large numbers of bacteria within the gingival sulcus cause gingival inflammation, periodontal disease, and tissue destruction.

    Issues with the Non-Specific Plaque Hypothesis

    • Too simplistic
    • Most gingivitis does not progress to periodontitis
    • Some sites suffer periodontal destruction, others do not.

    Specific Plaque/Microbial Shift Hypothesis

    • As periodontal disease develops, there's a shift from beneficial (mostly gram-positive) to specific pathogenic (mostly gram-negative) oral microbiota.

    Socransky's Microbial Complexes

    • Identifies various periodontal diseases caused by specific bacteria (e.g., Tannerella forsythia).
    • Grouped microbes into color-coded complexes.
    • Orange/red: major causative agents of periodontal disease
    • Yellow/green/blue/purple: compatible with gingival health

    Issues with the Specific Plaque Hypothesis

    • Red complex micro-organisms (e.g., P. gingivalis, T. forsythia) are found in stable, healthy periodontal sites.
    • Do these organisms directly cause periodontal destruction?
    • Recent research suggests a greater variety of oral microbes.
    • Type of oral microbes causing periodontal destruction are less certain.
    • Larger amounts of gram-positive bacteria found in periodontal pockets.

    Ecological Plaque Hypothesis

    • Changes in the subgingival environment trigger host inflammatory response.
    • Altered environment favours pathogenic bacteria; higher GCF flow, increased bleeding, raised pH, decreased oxygen concentration.
    • Damage to periodontal tissues follows.

    Support for Ecological Plaque Hypothesis

    • Deeper pocket sites and bleeding on probing have increased GCF.
    • GCF changes microbial ecology to enable pathogenic bacteria growth.
    • Environmental factors (e.g., GCF/pH/temperature/oxygen decrease) drive dysbiosis.
    • Subgingival debridement reduces pathogen numbers and halts bacterial nutrient supply.

    Microbial Homeostasis-Host Response Hypothesis

    • Pathogenic biofilm community triggers uncontrolled host immune response, damaging periodontal tissues.

    Support for Microbial Homeostasis-Host Response Hypothesis

    • Biofilm microbiota remains stable in health.
    • Research does not prove that bacterial pathogens are responsible for destruction.
    • Robust evidence shows that inflammation and immune response are the cause of tissue damage.

    Keystone Pathogen-Host Response Hypothesis

    • Keystone species in biofilm trigger a shift to a dysbiotic biofilm community, initiating uncontrolled host response, damaging periodontal tissues.

    Support for Keystone Pathogen-Host Response Hypothesis

    • Previous research lacked solid evidence of specific bacteria causing periodontal destruction.
    • Current evidence shows immune response is responsible for tissue destruction during periodontal disease.

    Aetiology of Periodontal Disease

    • Multifactorial: Microbial factors, environmental factors (e.g., smoking, poor oral hygiene, pre-existing pockets, plaque-retentive factors), severity of periodontitis, and host defence factors (e.g., PMN defects).

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    Periodontal Disease Microbiology PDF

    Description

    This quiz covers the microbial components involved in periodontal disease as part of the Oral and Dental Science module. Gain insights into the aetiology, mechanisms, and microbial transition from gingival health to periodontal disease, along with understanding virulence factors. Prepare to discuss both historical and current concepts related to the role of bacteria in periodontal disease.

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