Microbiology of Periodontal Diseases
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Questions and Answers

What does the nonspecific plaque hypothesis primarily focus on in relation to periodontal disease?

  • The quantity of plaque and its toxic products. (correct)
  • The nutritional status of the bacteria.
  • The type of bacteria present in the plaque.
  • The genetic predisposition of the host.

    • Which observation supported the abandonment of the nonspecific plaque hypothesis?

  • Mechanical removal of plaque is more effective than antibacterial treatments.
  • Some individuals with significant plaque show no signs of periodontitis. (correct)
  • All individuals with plaque develop periodontitis.
  • Plaque removal is ineffective for preventing gingivitis.

    • What is the primary basis for the specific plaque hypothesis?

  • The total volume of plaque determines disease severity.
  • Presence of calculus predicts periodontal disease.
  • Only specific microorganisms in the plaque are pathogenic. (correct)
  • All plaque contributes equally to tissue destruction.

    • According to the nonspecific plaque hypothesis, what would be an effective preventive measure against periodontal disease?

    <p>Mechanical removal of as much plaque as possible.</p> Signup and view all the answers

    What did advances in bacterial isolation techniques lead to in the study of periodontal diseases?

    <p>The abandonment of the nonspecific plaque hypothesis.</p> Signup and view all the answers

    What aspect does the specific plaque hypothesis emphasize in relation to periodontal disease?

    <p>The presence of specific pathogenic microorganisms.</p> Signup and view all the answers

    Which conclusion was drawn from the observations that some sites were unaffected while others advanced in disease?

    <p>Site-specific factors contribute to the disease process.</p> Signup and view all the answers

    What role does the host’s ability to detoxify bacterial products play in periodontal disease according to the nonspecific plaque hypothesis?

    <p>It determines the threshold for disease development.</p> Signup and view all the answers

    What was a significant limitation identified in clinical studies regarding the effectiveness of antibiotics in periodontal therapy?

    <p>The disease was reversible and symptoms returned after stopping treatment.</p> Signup and view all the answers

    Which of the following factors contributed to the uncertainty of chlorhexidine's effectiveness in periodontal treatment?

    <p>There was only an uncertain positive effect observed.</p> Signup and view all the answers

    According to the updated Nonspecific Plaque Hypothesis (NSPH), what played a critical role in the initiation of periodontal disease?

    <p>The overall microbial activity and virulence factors of bacteria.</p> Signup and view all the answers

    What percentage of bacterial species associated with periodontal disease was found to be uncultivable, leading to limitations in findings?

    <p>Approximately 50%</p> Signup and view all the answers

    Which of the following microbes was NOT mentioned as a potential periopathogen in periodontal disease?

    <p>Escherichia coli</p> Signup and view all the answers

    What is a key observation regarding gingivitis mentioned in the content?

    <p>Some individuals may experience gingivitis without significant tissue destruction.</p> Signup and view all the answers

    Which finding supports the idea that microbial colonization can lead to gingivitis?

    <p>Microbial colonization of sufficient quantity in the gingival crevice can induce gingivitis.</p> Signup and view all the answers

    What new perspective did the updated Nonspecific Plaque Hypothesis provide regarding the role of bacteria in periodontal disease?

    <p>All bacteria in dental plaque contribute to the virulence in some manner.</p> Signup and view all the answers

    What does the updated NSPH suggest about microbial composition and pathogenic potential?

    <p>Microbial composition directly influences the pathogenicity of the biofilm.</p> Signup and view all the answers

    According to the Ecological Plaque Hypothesis, disease results from what primary factor?

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

    What ecological factor does the presence of early colonizers of supragingival dental surfaces affect?

    <p>The environmental pH and redox potential.</p> Signup and view all the answers

    Which factor is NOT highlighted as significant according to the traditional EPH?

    <p>The host's genetic factors affecting bacterial composition.</p> Signup and view all the answers

    What is the main assertion of the Keystone Pathogen Hypothesis?

    <p>Low-abundance microbial pathogens can disproportionately influence the microbiota.</p> Signup and view all the answers

    What is an ecological consequence of bacterial metabolism in dental plaque?

    <p>Mutual dependencies in health and potential disease.</p> Signup and view all the answers

    Which of the following is NOT a key concept in understanding the composition of dental plaque?

    <p>The exclusive dominance of one microbial species.</p> Signup and view all the answers

    How does the Keystone Pathogen Hypothesis relate to clinical implications?

    <p>Identifying keystone pathogens could enhance treatment and preventive strategies.</p> Signup and view all the answers

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

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

    What condition facilitates the expression of type II LPS by P.gingivalis?

    <p>Increased concentration of iron.</p> Signup and view all the answers

    What is 'local chemokine paralysis' associated with in P.gingivalis infection?

    <p>Blocking IL-8 production by gingival epithelial cells.</p> Signup and view all the answers

    What effect do gingipains produced by P.gingivalis have on the complement system?

    <p>They cleave complement factors C3 and C5 into inactive fragments.</p> Signup and view all the answers

    What is the consequence of increased activation of the C5a receptor (C5aR) on leukocytes?

    <p>Impairment of leukocyte killing ability.</p> Signup and view all the answers

    Which mechanism allows P.gingivalis to manipulate the host immune response?

    <p>Secretion of serine phosphatase.</p> Signup and view all the answers

    What is a significant outcome of P.gingivalis' action on the oral microbiota?

    <p>Facilitating survival and multiplication of the microbial community.</p> Signup and view all the answers

    What characteristic of P.gingivalis strain lacking gingipains is noted?

    <p>It fails to change the oral microbiota and induce bone loss.</p> Signup and view all the answers

    What is the primary function of a keystone pathogen in a dysbiotic microbial community?

    <p>To trigger inflammation even when present in low numbers.</p> Signup and view all the answers

    Which of the following is NOT one of the mechanisms through which Porphyromonas gingivalis impairs host defenses?

    <p>Induction of excessive neutrophil apoptosis.</p> Signup and view all the answers

    Which role does interleukin 8 (IL-8) play in periodontal health?

    <p>Acts as a chemo-attractant for neutrophils.</p> Signup and view all the answers

    What is the relationship between the number of keystone pathogens and the overall bacterial load during periodontitis progression?

    <p>Keystone pathogen numbers decrease as bacterial load increases.</p> Signup and view all the answers

    What is the role of E-selectin in the immune response of periodontal tissue?

    <p>It facilitates the migration of neutrophils to pathogens.</p> Signup and view all the answers

    Which type of lipopolysaccharides (LPS) does Porphyromonas gingivalis utilize to manipulate the TLR response?

    <p>Type I and Type II.</p> Signup and view all the answers

    What role does the innate immune system play in relation to porphyromonas gingivalis?

    <p>It can be manipulated to promote pathogen survival.</p> Signup and view all the answers

    What characteristic distinguishes a keystone pathogen from dominant microbial species during inflammatory responses?

    <p>Keystone pathogens trigger inflammation even when present in lower numbers.</p> Signup and view all the answers

    Study Notes

    Microbiologic Specificity of Periodontal Diseases

    • Traditional Nonspecific Plaque Hypothesis (NSPH) proposed periodontal toxic products from plaque flora were proportional to gingival inflammation. Small amounts were neutralized by the host, while large amounts overcame the host's defenses. Host had a threshold for toxin detoxification. Prevention relied on removing as much plaque as possible.
    • This hypothesis was challenged by observations: some individuals with plaque and calculus, and gingivitis, never developed destructive periodontitis. Disease demonstrated site-specificity. Advancement of techniques to isolate & identify bacteria led to abandoning the NSPH.

    Specific Plaque Hypothesis

    • Only certain plaque is pathogenic, and pathogenicity depends on specific microorganisms. Plaque with specific pathogens results in periodontal disease.
    • Specific microorganisms produce substances that destroy host tissues.
    • The discovery of Actinomycetemcomitans as a pathogen in localized aggressive periodontitis supported the hypothesis.
    • Antibiotic treatment was effective in some cases but long-term use led to bacterial resistance

    Limitations of Specific Plaque Hypothesis

    • Clinical studies evaluating antibiotics as adjuncts in periodontal therapy showed the disease was reversible, then retained upon stopping therapy.
    • Long-term antibiotic use led to bacterial resistance, further questioning the hypothesis' effectiveness.
    • Chlorhexidine use after scaling/root planning had uncertain effects, and extensive use may not be warranted.

    Ecological Plaque Hypothesis

    • Periodontal disease results from an imbalance in the total microflora due to ecological stress, leading to the enrichment of "oral pathogens".
    • This hypothesis suggested an increased virulence of plaque due to an unfavorable host environment and favorable overgrowth by indigenous bacteria with a pathogenic potential.

    Keystone Pathogen Hypothesis

    • Certain species have a disproportionate effect on their environment relative to their abundance.
    • "Keystone-pathogen" hypothesis indicates that low-abundance microbial pathogens can cause inflammatory disease by changing normal microbiota composition and increasing pathogenic quantities.

    Additional Details on P. gingivalis

    • P. gingivalis can manipulate the innate immune system, facilitating its survival and multiplication & the entire microbial community.
    • P. gingivalis can manipulate TLR response, interleukin-8 (IL-8) response, and complement system.
    • These mechanisms (LPS types, serine phosphatase, and complement subversion) contribute to the subversion of host defenses leading to increased inflammation and periodontal disease.

    P. gingivalis Failure To Cause Dysbiosis and Periodontitis

    • Absence of commensal microbiota
    • Host lacking cellular receptors for immune response subversion
    • Bacteria lacking a crucial enzymatic activity to subvert leukocyte functions.

    Summary of Historical Plaque Hypothesis Development

    • From initial quantity-based approaches to more nuanced understandings of specific species and complex ecological interactions.
    • Identification of P. gingivalis as a keystone pathogen led to a more nuanced understanding of the role of keystone pathogens, influencing disease development.

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    Description

    Explore the complexities of periodontal diseases through the lens of microbiology. This quiz delves into the Traditional Nonspecific Plaque Hypothesis and challenges it with the Specific Plaque Hypothesis, emphasizing the role of specific microorganisms in disease progression.

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