Microbiologic Specificity of Periodontal Diseases
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What is the primary focus of the Nonspecific Plaque Hypothesis regarding periodontal disease?

  • The quality of bacteria present in the plaque.
  • The role of saliva in neutralizing plaque effects.
  • The quantity of plaque and its relationship with host defenses. (correct)
  • The virulence of specific pathogens in causing disease.

Which observation contradicted the Nonspecific Plaque Hypothesis?

  • Mechanical removal of plaque is ineffective in preventing disease.
  • Only specific bacteria are pathogenic in periodontal disease.
  • Some individuals with little plaque developed periodontitis.
  • Individuals with significant plaque sometimes do not develop periodontitis. (correct)

What conclusion did the Nonspecific Plaque Hypothesis support regarding disease prevention?

  • Improved dental hygiene practices should be emphasized.
  • Complete eradication of all bacteria is required.
  • Non-specific mechanical removal of plaque is key. (correct)
  • Nutritional changes are necessary for prevention.

What did the acceptance of the Specific Plaque Hypothesis primarily depend on?

<p>Identification of specific pathogenic microorganisms. (B)</p> Signup and view all the answers

What aspect of the Nonspecific Plaque Hypothesis was challenged by improved bacterial isolation techniques?

<p>The assumption that any plaque is equally harmful. (B)</p> Signup and view all the answers

What does the Specific Plaque Hypothesis predict regarding plaque composition?

<p>Only a few specific microorganisms in plaque can be pathogenic. (D)</p> Signup and view all the answers

How does the current clinical treatment for periodontal disease often relate to the Nonspecific Plaque Hypothesis?

<p>It continues to support mechanical removal of plaque. (A)</p> Signup and view all the answers

What is a key factor that challenges the idea of nonspecific pathogenicity in dental plaque?

<p>The variance in disease expression in affected sites. (C)</p> Signup and view all the answers

What is one significant limitation of antibiotics used in periodontal therapy?

<p>Long-term use can lead to bacterial resistance. (B)</p> Signup and view all the answers

Which of the following is NOT considered a potential periopathogen in periodontal disease?

<p>Corynebacterium (B)</p> Signup and view all the answers

According to the updated Non-specific Plaque Hypothesis, how does microbial colonization contribute to gingivitis?

<p>Microbial colonization in sufficient quantity can cause at least gingivitis. (A)</p> Signup and view all the answers

What was concluded about the use of chlorhexidine in managing periodontal disease?

<p>Its extensive use may be questioned due to uncertain effects. (C)</p> Signup and view all the answers

What is a major consideration of the updated Non-specific Plaque Hypothesis?

<p>The overall activity of multiple microbes may initiate disease. (A)</p> Signup and view all the answers

What observation supports the assertion that some people can have lifelong gingivitis without progressing to periodontitis?

<p>Some individuals lack specific factors that lead to tissue destruction. (D)</p> Signup and view all the answers

How are the species involved in periodontal disease described according to the findings?

<p>Approximately 50% of species are uncultivable and poorly understood. (A)</p> Signup and view all the answers

What does the statement about 'any microbial colonization of sufficient quantity' imply about periodontal health?

<p>A threshold level of microbial presence can lead to tissue inflammation. (C)</p> Signup and view all the answers

What is the primary role of keystone pathogens in polymicrobial diseases?

<p>They may trigger inflammation when present in low numbers. (B)</p> Signup and view all the answers

How does Porphyromonas gingivalis manipulate the immune system?

<p>By influencing the response of toll-like receptors. (A)</p> Signup and view all the answers

Which mechanism is NOT involved in the impairment of host defenses by P. gingivalis?

<p>Direct stimulation of neutrophil production. (C)</p> Signup and view all the answers

What is the significance of E-selectin in the context of periodontal health?

<p>It facilitates adhesion and migration of neutrophils. (A)</p> Signup and view all the answers

In which context is the 'KPH' most relevant?

<p>Developing diagnostic tools for polymicrobial diseases. (C)</p> Signup and view all the answers

What type of lipopolysaccharides does P. gingivalis use in manipulating the TLR response?

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

Why is interleukin 8 (IL-8) important in periodontal tissue?

<p>It serves as a key neutrophil chemo-attractant. (A)</p> Signup and view all the answers

What characterizes a keystone pathogen compared to dominant species?

<p>Keystone pathogens can influence host immune response at low numbers. (C)</p> Signup and view all the answers

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

<p>Activates the immune system (C)</p> Signup and view all the answers

How does P. gingivalis affect IL-8 production in the oral cavity?

<p>Blocks IL-8 production (C)</p> Signup and view all the answers

What is the effect of hemin concentration in the oral cavity?

<p>Increases Type II LPS expression (B)</p> Signup and view all the answers

What role do gingipains play in the complement system response?

<p>Cleaves complement factors and degrades their function (D)</p> Signup and view all the answers

What is a proposed consequence of local chemokine paralysis by P. gingivalis?

<p>Delayed neutrophil recruitment (A)</p> Signup and view all the answers

What is the relationship between C5a receptor (C5aR) and TLR2 in the context of P. gingivalis?

<p>C5aR crosstalk with TLR2 leads to increased inflammation and impaired leukocyte function (B)</p> Signup and view all the answers

Which of the following statements about P.gingivalis’ interactions with the immune system is accurate?

<p>Its gingipains can disarm complement factors (A)</p> Signup and view all the answers

What distinguishes Type II LPS in terms of immune response?

<p>It inhibits the immune response to P.gingivalis (C)</p> Signup and view all the answers

What does the Ecological Plaque Hypothesis (EPH) suggest as a cause for dental disease?

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

According to the Updated NSPH, what factor significantly contributes to differences in pathogenic potential of dental plaque?

<p>Differences in plaque microbial composition. (B)</p> Signup and view all the answers

Which of the following statements aligns with the Traditional Ecological Plaque Hypothesis (EPH)?

<p>It recognizes the influence of both bacterial metabolism and host environment. (B)</p> Signup and view all the answers

What is a key characteristic of keystone species as described in the Keystone Pathogen Hypothesis (KPH)?

<p>They have a limited overall abundance but a significant impact on the environment. (B)</p> Signup and view all the answers

Which ecological factors are influenced by changes in microbial composition in dental plaque?

<p>pH, nutrients, and redox potential. (A)</p> Signup and view all the answers

Which factor is NOT addressed by the traditional Ecological Plaque Hypothesis?

<p>The genetic factors of the host influencing plaque composition. (A)</p> Signup and view all the answers

What role do early colonizers of supragingival dental surfaces typically play?

<p>They occupy space and prevent disease-causing bacteria from settling. (B)</p> Signup and view all the answers

Why is the identification of keystone pathogens considered clinically important?

<p>It can lead to targeted treatments for inflammatory diseases. (B)</p> Signup and view all the answers

Flashcards

Nonspecific Plaque Hypothesis (NSPH)

The hypothesis that any plaque, regardless of specific bacteria, causes periodontal disease due to the amount of harmful products it produces, exceeding the host's capacity to neutralize them.

Specific Plaque Hypothesis

The hypothesis stating that particular types of bacteria in plaque are responsible for periodontal disease, not simply the total amount of plaque.

Periodontal Disease

A disease affecting the tissues that surround and support your teeth, which can lead to tooth loss.

Plaque

A sticky film of bacteria that forms on teeth.

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Virulence Factors

Substances produced by bacteria that allow them to cause harm to the host.

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Host's Defense Mechanisms

The body's natural ways of fighting off infection or damage from plaque bacteria.

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Site-Specificity

The concept that periodontal disease can affect some parts of the mouth more than others, even where there is a lot of plaque, and others may be unaffected.

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Mechanical Plaque Removal

Methods to physically remove plaque from teeth to prevent periodontal disease, like brushing and flossing.

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Actinomyces

A genus of bacteria often found in the mouth, sometimes linked to aggressive periodontitis.

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Specific Plaque Hypothesis (SPH)

The idea that certain bacteria cause periodontal disease, leading to the use of antibiotics for treatment.

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Antibiotic Resistance

The ability of bacteria to survive even when treated with antibiotics.

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Chlorhexidine

An antiseptic used to control plaque and gingivitis, but its effectiveness is debated.

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Uncultivable Species

Types of bacteria that cannot be grown in a lab.

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Ecological Plaque Hypothesis

This hypothesis states that periodontal disease arises from an imbalance in the oral microbiome due to ecological stress, leading to the overgrowth of certain 'pathogenic' bacteria.

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What changes the dental plaque environment?

Changes in the composition of dental plaque directly affect ecological factors like nutrient availability, pH, and oxygen levels.

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Keystone Pathogen Hypothesis

This hypothesis states that certain low-abundance bacteria can significantly impact the oral microbiome, leading to disease by changing the composition and quantity of other bacteria.

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Keystone Pathogen

A low-abundance bacterial species that has a disproportionately large impact on the oral microbiome, leading to disease.

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What's the impact of keystone pathogens?

Keystone pathogens can trigger disease development by increasing the quantity of normal microbiota and changing its composition.

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Clinical benefits of identifying keystone pathogens

Identifying these pathogens could lead to improved targeted therapies and preventive measures for periodontal disease.

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How do keystone pathogens affect the microbiome?

They cause an increase in the total number of bacteria in the microbiome, but also change the relative proportion of different types of bacteria.

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What is unique about keystone pathogens?

Despite their low abundance, they have a significant impact on the oral microbiome and can trigger disease development.

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TLR4 Agonist

A substance that activates TLR4, a receptor on immune cells, triggering an immune response.

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TLR4 Antagonist

A substance that blocks TLR4, preventing activation and suppressing an immune response.

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Type I LPS

A form of LPS that acts as a TLR4 agonist, stimulating the immune system.

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Type II LPS

A form of LPS that acts as a TLR4 antagonist, inhibiting the immune system.

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Hemin

An iron-containing molecule found in gingival crevicular fluid (GCF).

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Local Chemokine Paralysis

A process where Porphyromonas gingivalis blocks the production of IL-8, a signaling molecule that attracts neutrophils to fight infection.

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Gingipains

Proteinases produced by Porphyromonas gingivalis that can cleave complement factors, disrupting the complement system.

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C5aR Activation

Increased activation of the C5a receptor on leukocytes, caused by gingipains.

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Keystone Pathogen (KPH)

A bacterial species that exerts a disproportionate influence on the microbial community and disease progression, even if present in relatively low numbers.

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Porphyromonas gingivalis

A keystone pathogen implicated in periodontal disease, known for its ability to manipulate the host's immune system.

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KPH and Host Immune System

The host's immune response is crucial in how a keystone pathogen like P.gingivalis influences disease progression.

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KPH: TLR Response Manipulation

P.gingivalis can manipulate the host's Toll-like receptor (TLR) response using different types of lipopolysaccharides (LPS).

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KPH: IL-8 Subversion

P.gingivalis can disrupt the normal function of interleukin-8 (IL-8), a neutrophil chemoattractant.

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KPH: Complement System Corruption

P.gingivalis can interfere with the complement system, a crucial part of the immune response.

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Dominant vs. Keystone Pathogens

Dominant species influence inflammation through sheer numbers, while keystone pathogens can trigger inflammation even in low numbers.

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Study Notes

Microbiologic Specificity of Periodontal Diseases

  • The traditional nonspecific plaque hypothesis (NSPH) proposed that the amount of plaque determined its pathogenicity.
  • This hypothesis suggested that the host has a threshold for neutralizing toxic products from plaque. Exceeding this threshold leads to disease.
  • However, observations contradicted this. Some individuals with significant plaque and calculus did not develop destructive periodontitis (gum disease).
  • There was also site-specificity to the disease, with some sites unaffected in individuals despite advanced disease in others.

Specific Plaque Hypothesis

  • The specific plaque hypothesis (SPH) proposes that only specific pathogenic microorganisms, in plaque, cause periodontal disease.
  • The acceptance of the SPH was aided by the discovery of A. actinomycetemcomitans as a pathogen in aggressive periodontitis.
  • However, several limitations to the usefulness of the SPH were identified, including antibiotic resistance in clinical settings and uncertainty regarding the effect of chlorhexidine.

Ecologic Plaque Hypothesis

  • The ecological plaque hypothesis (EPH) suggests that periodontal disease results from an imbalance in the total microbial flora, and not just the quantity of plaque.
  • This imbalance could be caused by environmental stress, resulting in an increase in the relative abundance of "oral pathogens."

Keystone Pathogen Hypothesis

  • The keystone pathogen hypothesis (KPH) highlights the disproportionate effects of certain low-abundance microbial pathogens.
  • This hypothesis asserts that these keystone pathogens significantly impact the oral microbiota, and can cause inflammatory disease by increasing other normally present microorganisms and causing changes in composition.

Porphyromonas gingivalis

  • P. gingivalis's various mechanisms impair host defenses by manipulating the TLR response, altering the interleukin-8 (IL-8) response, and subverting the complement system.

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Description

Explore the differences between the traditional nonspecific plaque hypothesis and the specific plaque hypothesis in periodontal diseases. Understand how specific microorganisms, like A. actinomycetemcomitans, play a role in disease pathogenesis and the implications for treatment. This quiz will help clarify key concepts in periodontal microbiology.

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