Microbiologic Specificity of Periodontal Diseases
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Questions and Answers

What is the name of the hypothesis which states that periodontal toxic products are proportional to the severity of the gingival inflammation?

Nonspecific Plaque Hypothesis (NSPH)

According to the NSPH, large amounts of plaque would overcome the host's defenses.

True

Which of the following observations contradicted the conclusions of the NSPH? (Select all that apply)

  • Microbial composition changes in ecological factors.
  • The identification of keystone pathogens provided evidence for the existence of specific pathogens. (correct)
  • The environment influences the composition of dental plaque.
  • Some individuals with significant amounts of plaque never developed destructive periodontitis. (correct)
  • Improvement in techniques to isolate and identify bacteria led to the abandonment of the NSPH. (correct)
  • Individuals with periodontitis demonstrated site specificity in the pattern of disease. (correct)
  • Long-term use of antibiotics led to bacterial resistance. (correct)
  • Clinical studies showed that the effectiveness of antibiotics was not always sustained. (correct)

    • What is the name of the hypothesis that assumes only certain plaque is pathogenic, and its pathogenicity depends on the presence of specific microorganisms?

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

    The Specific Plaque Hypothesis was encouraged by identifying Actinomyces actinomycetemcomitans as a pathogenic agent in localized aggressive periodontitis.

    <p>True</p> Signup and view all the answers

    What are the main limitations associated with the Specific Plaque Hypothesis?

    <p>Limitations include the effectiveness of antibiotics, bacterial resistance, the presence of other potential periopathogens, and difficulties in identifying periopathogens due to uncultivable species and bias toward easily cultivable ones.</p> Signup and view all the answers

    What does the Updated Nonspecific Plaque Hypothesis emphasize?

    <p>The updated NSPH states that all bacteria contribute to the virulence of the microflora by having a role in colonization, evasion of the defense mechanism, and/or provocation of inflammation and tissue destruction.</p> Signup and view all the answers

    What is the main idea behind the Ecologic Plaque Hypothesis?

    <p>Periodontal disease arises because of a microbial imbalance resulting in a shift toward disease-related microorganisms.</p> Signup and view all the answers

    The Ecologic Plaque Hypothesis proposes that all bacteria in plaque have pathogenic potential.

    <p>False</p> Signup and view all the answers

    What is the main idea proposed by the Keystone Pathogen Hypothesis?

    <p>Certain low-abundance microbial pathogens play a disproportional role in periodontal disease development by creating a dysbiosis altering the normal microbiota.</p> Signup and view all the answers

    What are the main clinical benefits of identifying keystone pathogens?

    <p>Identifying keystone pathogens could lead to the development of novel treatments targeting only a limited number of bacterial targets and the creation of more targeted diagnostic tools.</p> Signup and view all the answers

    Which of the following is NOT a key mechanism by which Porphyromonas gingivalis impairs the host's defense system?

    <p>Directly killing neutrophils</p> Signup and view all the answers

    The TLR response is manipulated by P. gingivalis through the use of two types of lipopolysaccharides, type I and type II, where type I is a TLR4 agonist and type II is a TLR4 antagonist.

    <p>True</p> Signup and view all the answers

    What is the main source of iron found in the oral cavity, and what type of LPS is it associated with?

    <p>The main source of iron is hemin, found in the gingival crevicular fluid (GCF), and it is associated with type II LPS.</p> Signup and view all the answers

    The IL-8 response is manipulated by P. gingivalis by inhibiting the production of IL-8, leading to delays in neutrophil recruitment.

    <p>True</p> Signup and view all the answers

    What is meant by 'local chemokine paralysis'?

    <p>Local chemokine paralysis refers to the process where bacteria inhibit the production of chemoattractant molecules, like IL-8, ultimately preventing the recruitment of neutrophils to sites of infection.</p> Signup and view all the answers

    The complement system response is manipulated by P. gingivalis by directly attacking the complement system's proteins.

    <p>False</p> Signup and view all the answers

    What are gingipains, and what role do they play in the complement system response by P. gingivalis?

    <p>Gingipains are proteinases produced by <em>P. gingivalis</em> that can cleave complement factors C3 and C5 into active fragments, which can then be degraded by gingipains, resulting in a loss of their function.</p> Signup and view all the answers

    The increased activation of the C5aR receptor leads to increased inflammation but also impairs the killing capacity of leukocytes.

    <p>True</p> Signup and view all the answers

    A P. gingivalis strain lacking gingipains successfully induced bone loss in mice.

    <p>False</p> Signup and view all the answers

    What are the key conditions that must be met for P. gingivalis to cause dysbiosis and periodontitis?

    <p>The presence of commensal microbiota, the presence of cellular receptors in the host, and the presence of the crucial enzymatic activity in <em>P. gingivalis</em> are all necessary for the development of dysbiosis and periodontitis.</p> Signup and view all the answers

    What is the main conclusion about keystone pathogens in the context of periodontitis?

    <p>Keystone pathogens utilize a combination of known and unknown mechanisms to manipulate the innate defense system, leading to destructive periodontitis.</p> Signup and view all the answers

    Study Notes

    Microbiologic Specificity of Periodontal Diseases

    • Traditional nonspecific plaque hypothesis (NSPH) proposed that the amount of plaque determined its pathogenicity. The theory suggested that the host could neutralize harmful products from small amounts of plaque but larger amounts would overcome the host's defenses.
    • Evidence contradicted the NSPH. Some individuals with significant plaque and calculus did not develop destructive periodontitis. Disease often showed site-specificity, with some sites unaffected while others had advanced disease.
    • Improvements in identifying bacteria in the mid-20th century led to the abandonment of the NSPH. The shift favored the specific plaque hypothesis or an ecological approach.

    Specific Plaque Hypothesis

    • This hypothesis states that only specific plaque components are pathogenic. Periodontal disease results when plaque harbors specific bacterial pathogens and their associated substances that harm the tissue.
    • Identification of bacteria such as A. actinomycetemcomitans in aggressive periodontitis supported the hypothesis, pointing to specific pathogens rather than simply large amounts of bacteria.
    • Limitations to the specific plaque hypothesis include clinical studies showing that antibiotic use as an adjunct in therapy was only temporarily effective and some therapies showed uncertain positive effects.

    Ecological Plaque Hypothesis

    • This hypothesis suggests that periodontal disease arises from an imbalance in the oral microflora due to ecological stress. It focuses on the role of the environment and how shifts in the microbial community can cause disease-related organisms to overgrow.
    • The environment, including nutrients, pH, and redox potential, influence the composition of the microflora, and this community in turn can influence those environmental factors.
    • This concept acknowledges the complexity of the oral microbiota and its dynamic interaction with the host.

    Keystone Pathogen Hypothesis

    • This hypothesis proposes that certain species, termed "keystone pathogens," influence their environment disproportionately to their abundance.
    • Keystone pathogens can cause inflammatory disease by changing the number and composition of other microbes in the ecosystem.
    • Identifying keystone pathogens could lead to more targeted and successful treatment strategies for periodontitis. This would be useful for complex polymicrobial infections, as limited target areas could improve treatment.

    Evidence Supporting the Importance of P. gingivalis

    • P. gingivalis can manipulate the host's immune response, allowing it to survive and multiply and influencing the community of microbes present.
    • This bacterium can manipulate the body's response through actions like manipulating TLR signaling, inhibiting the production of interleukins like IL-8, and interfering with the complement system.
    • This disruption of normal immune responses facilitates an environment that can lead to increased inflammatory response and progression of the disease, as well as reduced leukocyte killing and potentially increasing the tissue damage.

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    Description

    Explore the evolution of theories regarding periodontal diseases in this quiz. From the nonspecific plaque hypothesis to the specific plaque hypothesis, learn how scientific advancements in microbiology have shaped our understanding of periodontal health. Test your knowledge on the key components that contribute to periodontal diseases and their specific microbial associations.

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