Periodontal Diseases and Microbiology
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Questions and Answers

What was a major flaw in the nonspecific plaque hypothesis?

  • It recognized the virulence levels of specific bacteria.
  • It focused on the presence of specific microorganisms in plaque.
  • It assumed all plaque has the same potential for pathogenicity. (correct)
  • It provided a comprehensive treatment plan for periodontal diseases.

    • Which hypothesis emphasizes the role of specific microorganisms in periodontal disease?

  • Specific Plaque Hypothesis (correct)
  • Nonspecific Plaque Hypothesis
  • Mechanical Plaque Removal Hypothesis
  • Ecological Plaque Hypothesis

    • How does the nonspecific plaque hypothesis suggest periodontal disease can be prevented?

  • Through non-specific mechanical removal of plaque. (correct)
  • Through improved oral hygiene techniques focused on specific sites.
  • By using antibacterial medications.
  • By specific targeting of harmful bacteria.

    • What observation contradicted the conclusions of the nonspecific plaque hypothesis?

    <p>There are individuals with high plaque levels who do not develop periodontitis.</p> Signup and view all the answers

    What is a key factor that the specific plaque hypothesis predicts will lead to periodontal disease?

    <p>Presence of pathogenic microorganisms in plaque.</p> Signup and view all the answers

    In the context of periodontal diseases, what does the term 'site-specificity' refer to?

    <p>Certain sites are unaffected even in individuals with periodontitis.</p> Signup and view all the answers

    What did advancements in microbiological techniques lead to regarding the nonspecific plaque hypothesis?

    <p>Abandoning it in favor of newer hypotheses.</p> Signup and view all the answers

    According to the nonspecific plaque hypothesis, what determines the pathogenicity of periodontal disease?

    <p>The total quantity of plaque present.</p> Signup and view all the answers

    What is the primary reason for the shift in pathogenic potential according to the updated NSPH?

    <p>Environmental changes affecting microbial composition</p> Signup and view all the answers

    What does the Ecological Plaque Hypothesis suggest is the cause of dental disease?

    <p>An imbalance in the total microflora due to ecological stress</p> Signup and view all the answers

    What role do early colonizers of supragingival dental surfaces play in the composition of dental plaque?

    <p>They produce byproducts that alter the redox potential</p> Signup and view all the answers

    In the context of dental plaque development, what is meant by a 'keystone pathogen'?

    <p>A low-abundance pathogen with a disproportionate effect on the microbiota</p> Signup and view all the answers

    Why does the traditional Ecological Plaque Hypothesis fail to completely explain dental disease?

    <p>It neglects the genetic factors of the host</p> Signup and view all the answers

    What is a significant factor that affects the composition of dental plaque?

    <p>The genetics of the individual host</p> Signup and view all the answers

    How do bacterial species influence their environment within dental plaque?

    <p>By modifying environmental factors like pH and redox potential</p> Signup and view all the answers

    What is a consequence of ecological stress as mentioned in the Ecological Plaque Hypothesis?

    <p>Enrichment of oral pathogens within the microbial community</p> Signup and view all the answers

    What is one of the limitations associated with the hypothesis that specific periopathogens cause periodontal disease?

    <p>Bacterial resistance can develop with long-term antibiotic use.</p> Signup and view all the answers

    According to the updated Nonspecific Plaque Hypothesis, what plays a role in the virulence of microflora in dental plaque?

    <p>Bacteria's ability to provoke inflammation and tissue destruction.</p> Signup and view all the answers

    Which types of bacteria were identified as potential periopathogens associated with periodontal disease?

    <p>Actinomyces and Streptococci.</p> Signup and view all the answers

    What misconception about chlorhexidine usage in periodontal therapy is highlighted?

    <p>The positive effects of chlorhexidine treatment remain uncertain.</p> Signup and view all the answers

    What did the hypothesis state regarding microbial colonization in the gingival crevice?

    <p>Any microbial colonization of sufficient quantity can at least cause gingivitis.</p> Signup and view all the answers

    Which of the following best describes the occurrence of gingivitis in individuals?

    <p>Some individuals can have it for life without tissue destruction.</p> Signup and view all the answers

    What does the updated Nonspecific Plaque Hypothesis (NSPH) emphasize about oral health?

    <p>Virulence is influenced by the overall activity of microbial populations.</p> Signup and view all the answers

    What aspect of periodontal disease treatment is questioned due to clinical studies on antibiotics?

    <p>Antibiotic treatment reversibility post-therapy.</p> Signup and view all the answers

    What is the primary role of Type I in relation to TLR4?

    <p>It activates the immune system.</p> Signup and view all the answers

    What factor influences the type of LPS expressed by Porphyromonas gingivalis?

    <p>Concentration of hemin.</p> Signup and view all the answers

    How does Porphyromonas gingivalis block IL-8 production in host cells?

    <p>By secreting a serine phosphatase.</p> Signup and view all the answers

    What is local chemokine paralysis primarily associated with?

    <p>Delayed neutrophil wall formation.</p> Signup and view all the answers

    What mechanism does Porphyromonas gingivalis use to interfere with the complement system?

    <p>Producing membrane-bound and soluble proteinases.</p> Signup and view all the answers

    What does C5aReceptor (C5aR) involvement in P.gingivalis infection lead to?

    <p>Impaired complement function.</p> Signup and view all the answers

    What role do gingipains play in the pathogenesis of periodontitis?

    <p>Accelerate periodontitis development and bone loss.</p> Signup and view all the answers

    What was observed in a P.gingivalis strain that lacks gingipains?

    <p>No impact on the oral microbiota and bone loss.</p> Signup and view all the answers

    What role do keystone pathogens play in the development of polymicrobial diseases?

    <p>They manipulate the host's immune response when present in low numbers.</p> Signup and view all the answers

    Which of the following statements about Porphyromonas gingivalis is false?

    <p>It exists in high quantities throughout advanced periodontal diseases.</p> Signup and view all the answers

    What is a primary function of E-selectin in periodontal health?

    <p>It is responsible for the migration of neutrophils from gingival tissue.</p> Signup and view all the answers

    Which mechanism is not associated with P.gingivalis's impairment of host defenses?

    <p>Enhancement of the complement system.</p> Signup and view all the answers

    How do lipopolysaccharides (LPS) produced by P.gingivalis differ in type?

    <p>They both manipulate the TLR response but differ in structure.</p> Signup and view all the answers

    What is the significance of the neutrophil wall in periodontal health?

    <p>It acts as a barrier between plaque and epithelial cells.</p> Signup and view all the answers

    In advanced stages of periodontal disease, how does the presence of keystone pathogens change?

    <p>They can increase in number but decrease in proportion to the bacterial load.</p> Signup and view all the answers

    What role do toll-like receptors (TLRs) play in the immune response?

    <p>They help detect a broad range of pathogens.</p> Signup and view all the answers

    Study Notes

    Microbiologic Specificity of Periodontal Diseases

    • The nonspecific plaque hypothesis (NSPH) proposed that the amount of plaque determined its pathogenicity, without considering the virulence of the bacteria.
    • The NSPH suggested that if the host's capacity to neutralize plaque toxins was exceeded, inflammation and disease would occur.
    • This hypothesis was refuted by the observation that some individuals with plaque and calculus, along with gingivitis, did not develop periodontitis.
    • Site-specific disease patterns were observed, with some sites unaffected while others had advanced disease.
    • The ability to isolate and identify oral bacteria in the mid-20th century led to the abandonment of the NSPH.

    Specific Plaque Hypothesis

    • The specific plaque hypothesis maintains that only certain plaque-associated microorganisms are pathogenic, and their pathogenicity depends on the presence of specific microorganisms.
    • This hypothesis suggests that specific periodontal pathogens cause periodontal disease by producing substances that damage host tissues.
    • The acceptance of a specific plaque hypothesis was aided by the identification of A. actinomycetemcomitans as a pathogen in aggressive periodontitis.
    • Certain limitations associated with this hypothesis include: difficulty establishing the effectiveness of antibiotics, resistance to antibiotics, and uncertain benefits from chlorhexidine.

    Ecological Plaque Hypothesis

    • The ecological plaque hypothesis (EPH) proposes that disease results from an imbalance in the total microflora due to ecological stress.
    • This imbalance can lead to an overgrowth of pathogenic microorganisms.
    • The theory emphasizes the importance of the host-dependent environment in the selection of colonizing bacteria, while acknowledging the influence of genetic factors.

    Keystone Pathogen Hypothesis

    • The keystone pathogen hypothesis (KPH) suggests that certain low-abundance species have a disproportionate effect on their environment.
    • These species, with limited abundance, can cause inflammatory disease by altering the bacterial community composition and increasing the abundance of other pathogens.
    • Identifying keystone pathogens could lead to targeted treatments for polymicrobial diseases.

    Mechanisms of P.gingivalis

    • P. gingivalis manipulates the host immune system by influencing the TLR response, subverting the IL-8 response, and interfering with the complement system.
    • Lipopolysaccharides (LPS) produce different effects depending on concentration and composition.
    • P. gingivalis can reduce the TLR4 response through the production of Type II LPS, thereby reducing inflammation.
    • The keystone pathogen (P. gingivalis) can block the production of IL-8.
    • This can prevent the recruitment of neutrophils needed for the elimination of microbes.

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    Description

    Explore the microbiologic aspects of periodontal diseases through this quiz. Understand the nonspecific and specific plaque hypotheses, their implications for disease progression, and the role of oral bacteria in periodontal health. Test your knowledge on key concepts and observations related to periodontal diseases.

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