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?

Uncontrolled host inflammatory responses are the main cause of tissue destruction. Signup and view all the answers

What distinguishes the keystone pathogen hypothesis from earlier periodontitis theories?

It identifies a singular bacterial species that impacts microbial balance. Signup and view all the answers

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

A pathogenic microbial biofilm Signup and view all the answers

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

The accumulation of bacterial biofilms leads to tissue destruction. Signup and view all the answers

What does the Ecological Plaque Hypothesis propose?

Nonspecific bacteria lead to an inflammatory response altering the environment Signup and view all the answers

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

Specific Plaque Hypothesis Signup and view all the answers

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

Microbial Homeostasis-Host Response Hypothesis Signup and view all the answers

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

They fail to explain variable disease progression in individuals. 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?

Subgingival bacterial populations Signup and view all the answers

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

Ecological Plaque Hypothesis Signup and view all the answers

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

They may correlate with deeper probing depths and higher GCF flow Signup and view all the answers

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

They are strongly associated with inflammation but not necessarily initiators Signup and view all the answers

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

Over 700 Signup and view all the answers

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

They are major contributors to the disease's initiation and progression 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?

Keystone Pathogen-Host Response Hypothesis Signup and view all the answers

What characterizes the Keystone Pathogen-Host Response Hypothesis?

It suggests that certain pathogens play a crucial role in disease development Signup and view all the answers

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

It fails to explain the presence of pathogens in healthy individuals. 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?

Nonspecific Plaque Hypothesis Signup and view all the answers

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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