Role of Bacteria in Periodontal Disease

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Questions and Answers

What does the Keystone Pathogen-Host Response Hypothesis suggest about dysbiotic microbes in the biofilm community?

  • They are directly caused by specific bacterial pathogens.
  • They can trigger the host inflammatory response leading to tissue damage. (correct)
  • They result from an abundance of non-specific biofilm bacteria.
  • They are beneficial for maintaining periodontal health.

Which hypothesis claims that uncontrolled host inflammatory responses are responsible for tissue destruction in periodontitis?

  • Keystone Pathogen Hypothesis
  • Specific Plaque Hypothesis
  • Nonspecific Plaque Hypothesis
  • Microbial Homeostasis-Host Response Hypothesis (correct)

How is the ecological plaque hypothesis different from the Keystone Pathogen Hypothesis?

  • It suggests that a single keystone species triggers dysbiosis.
  • It emphasizes changes in the subgingival environment and microbial composition. (correct)
  • It dismisses the role of host responses in periodontitis.
  • It focuses solely on specific bacterial species causing damage.

Which statement accurately reflects the findings of decades of periodontal research?

<p>Uncontrolled host inflammatory responses are the main cause of tissue destruction. (C)</p> Signup and view all the answers

What distinguishes the keystone pathogen hypothesis from earlier periodontitis theories?

<p>It identifies a singular bacterial species that impacts microbial balance. (A)</p> Signup and view all the answers

What is a necessary condition for the development of periodontitis according to recent perspectives?

<p>A pathogenic microbial biofilm (B)</p> Signup and view all the answers

What is the main premise of the Nonspecific Plaque Hypothesis in relation to periodontal disease?

<p>The accumulation of bacterial biofilms leads to tissue destruction. (A)</p> Signup and view all the answers

What does the Ecological Plaque Hypothesis propose?

<p>Nonspecific bacteria lead to an inflammatory response altering the environment (D)</p> Signup and view all the answers

Which hypothesis proposes that specific pathogenic bacteria are essential for the development of periodontal disease?

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

Which hypothesis suggests that host-related and environmental factors contribute significantly to periodontal disease progression?

<p>Microbial Homeostasis-Host Response Hypothesis (C)</p> Signup and view all the answers

What limitation is shared by both the Nonspecific and Specific Plaque Hypotheses?

<p>They fail to explain variable disease progression in individuals. (B)</p> Signup and view all the answers

Which of the following factors is NOT considered a contributor to periodontal disease progression according to the Microbial Homeostasis-Host Response Hypothesis?

<p>Subgingival bacterial populations (C)</p> Signup and view all the answers

Which of the following hypotheses emphasizes the ecological factors influencing microbial populations in periodontal disease?

<p>Ecological Plaque Hypothesis (A)</p> Signup and view all the answers

What is suggested by the findings associated with the Ecological Plaque Hypothesis regarding sites with bleeding upon probing?

<p>They may correlate with deeper probing depths and higher GCF flow (C)</p> Signup and view all the answers

Which statement best describes the relationship between red complex bacteria and periodontal disease?

<p>They are strongly associated with inflammation but not necessarily initiators (D)</p> Signup and view all the answers

How many bacterial species have been identified in the human oral cavity?

<p>Over 700 (A)</p> Signup and view all the answers

What role do host factors play in periodontal disease according to the recent perspectives?

<p>They are major contributors to the disease's initiation and progression (B)</p> Signup and view all the answers

Which hypothesis suggests that the presence of certain bacteria can be found in both healthy and diseased sites in the oral cavity?

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

What characterizes the Keystone Pathogen-Host Response Hypothesis?

<p>It suggests that certain pathogens play a crucial role in disease development (C)</p> Signup and view all the answers

What significant issue exists with the Specific Plaque Hypothesis according to the content?

<p>It fails to explain the presence of pathogens in healthy individuals. (B)</p> Signup and view all the answers

Which of the following refers to a historical theory that emphasizes the overall abundance of bacteria in biofilms without specific pathogens being highlighted?

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

Flashcards

Oral Microorganisms

Various types of bacteria found in the human oral cavity.

Anthonie van Leeuwenhoek

The scientist who first described oral microorganisms using a microscope in 1683.

Nonspecific Plaque Hypothesis

The hypothesis that a large amount of bacteria in a biofilm leads to periodontal disease.

Specific Plaque Hypothesis

The hypothesis that specific pathogenic bacteria, in the biofilm, cause periodontal disease.

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Periodontal Disease

An inflammation of the tissues that support the teeth, often resulting from bacterial plaque.

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Periodontitis

Advanced stage of periodontal disease that destroys the tissues and bone.

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Microbial Biofilm

A community of bacteria, forming a sticky layer often attached to surfaces, including teeth.

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Keystone Pathogen

A crucial bacteria species in a biofilm community, whose presence or absence affects its composition and function.

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Ecological Plaque Hypothesis

Focus on the complex relationships between bacteria and their effects on disease

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Ecological Plaque Hypothesis

The accumulation of nonspecific bacteria triggers the host inflammatory response, which alters the gingival sulcus environment, leading to changes in microbial composition.

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Microbial Homeostasis-Host Response Hypothesis

Although plaque biofilms cause gingivitis, the pathogenic bacteria are not the direct cause of tissue destruction in periodontitis; host factors are.

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Periodontal Disease

A disease of the supporting structures of the teeth, involving inflammation and tissue destruction.

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Pathogenic biofilm

A microbial community that's necessary for periodontal disease development, but not a sufficient cause alone.

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GCF flow

Gingival crevicular fluid flow; it's strongly associated with disease severity.

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Red complex microorganisms

Microbes strongly linked to inflammation, but not necessarily the cause of the disease.

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Nonspecific Plaque Hypothesis

An older theory suggesting that any type of plaque buildup causes disease.

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Specific Plaque Hypothesis

An older theory proposing specific types of bacteria are the sole cause of the disease.

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Keystone Pathogen Hypothesis

A specific bacterial species triggers a shift from beneficial to harmful microbes in the biofilm, leading to a destructive host response in periodontitis.

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Microbial Homeostasis-Host Response Hypothesis

Changes in the microbial balance (from beneficial to pathogenic) trigger an excessive inflammatory response, damaging periodontal tissues.

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Ecological Plaque Hypothesis

Changes in subgingival environment influence the specific microbes in the biofilm community; the resulting pathogenic composition triggers periodontal tissue destruction.

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Specific Plaque Hypothesis

(Historical) The presence of specific bacteria in the biofilm directly causes tissue destruction in periodontitis.

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Nonspecific Plaque Hypothesis

(Historical) An abundance of biofilm bacteria causes the tissue destruction in periodontitis.

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Dysbiotic biofilm community

A harmful microbial community in a biofilm causing damage to periodontal tissues

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Periodontal tissues

The tissues supporting the teeth (gums, ligaments, bone).

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Uncontrolled host response

An excessive inflammatory and immune reaction initiated by the dysbiotic biofilm community leading to tissue damage.

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Study Notes

Changing Evidence for the Role of Bacteria in Periodontal Disease

  • Over 700 bacterial species found in the oral cavity.
  • Despite extensive study, specific bacterial pathogens for periodontitis still unknown.
  • Five hypotheses proposed to explain the role of bacteria in periodontal disease:
    • Nonspecific Plaque Hypothesis
    • Specific Plaque Hypothesis
    • Ecological Plaque Hypothesis
    • Microbial Homeostasis-Host Response Hypothesis
    • Keystone Pathogen-Host Response Hypothesis

Historical Perspectives on the Role of Bacteria

  • Nonspecific Plaque Hypothesis: Bacterial accumulation (plaque biofilm) leads to periodontal disease.

    • Too simplistic
    • Doesn't explain why some with heavy plaque don't develop periodontitis, while others with little plaque do.
    • Doesn't explain why some areas of a person's mouth are affected more than others.

  • Specific Plaque Hypothesis: Specific pathogenic bacteria and their products lead to periodontal disease.

    • Focuses on microbial composition, not just quantity.
    • Suggests a shift from beneficial to pathogenic bacteria as periodontitis develops.
      • Bacteria change from predominantly gram-positive aerobes to gram-negative anaerobes.
    • Problems with this hypothesis include:
      • Select pathogens are found in healthy sites.
      • Whether these bacteria are the direct cause of periodontal breakdown is questionable.

Contemporary Perspectives on the Role of Bacteria

  • Ecological Plaque Hypothesis: Combines elements of the nonspecific and specific plaque hypotheses.

    • Microbial accumulation triggers a host inflammatory response.
    • The host response alters the environment, favoring growth of pathogenic bacteria.
    • Shifts in the environment drive changes in microbial composition leading to periodontal disease.

  • Microbial Homeostasis-Host Response Hypothesis: Suggests that while plaque biofilms trigger inflammation, the pathogen bacteria themselves are not the direct cause of periodontal tissue destruction.

    • Host factors, genetics, and environment play a crucial role.

  • Keystone Pathogen-Host Response Hypothesis: Explains how a small number of keystone species (e.g., P. gingivalis) can cause a shift from beneficial to pathogenic microbes.

    • This shift triggers the host response, which causes tissue destruction.
    • This hypothesis suggests both a polymicrobial dysbiotic biofilm and a susceptible host are required for periodontitis initiation.

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