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Questions and Answers
What factor must occur for gingivitis to progress to periodontitis according to Page and Schroeder?
What factor must occur for gingivitis to progress to periodontitis according to Page and Schroeder?
Which phenomenon triggers a strong inflammatory response linked to periodontal tissue destruction?
Which phenomenon triggers a strong inflammatory response linked to periodontal tissue destruction?
What does the current evidence suggest is the main cause of tissue destruction in periodontal disease?
What does the current evidence suggest is the main cause of tissue destruction in periodontal disease?
Which of the following is NOT considered an environmental factor contributing to periodontal disease?
Which of the following is NOT considered an environmental factor contributing to periodontal disease?
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What is the role of keystone species in the context of periodontal disease?
What is the role of keystone species in the context of periodontal disease?
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Which statement about the biofilm microbiota related to periodontal health is true?
Which statement about the biofilm microbiota related to periodontal health is true?
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What is the primary microbial component involved in the aetiology of periodontal disease?
What is the primary microbial component involved in the aetiology of periodontal disease?
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Which aspect is NOT a mechanism involved in periodontal disease development?
Which aspect is NOT a mechanism involved in periodontal disease development?
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Which of the following best describes the transition of bacteria from gingival health to periodontal disease?
Which of the following best describes the transition of bacteria from gingival health to periodontal disease?
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Which of the following is a virulence factor deployed by oral microorganisms?
Which of the following is a virulence factor deployed by oral microorganisms?
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What role does inflammation play in periodontal disease?
What role does inflammation play in periodontal disease?
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In the context of periodontal disease, which is the most significant route of transmission for infectious agents?
In the context of periodontal disease, which is the most significant route of transmission for infectious agents?
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Which of the following statements is true regarding the immune response to pathogens in periodontal disease?
Which of the following statements is true regarding the immune response to pathogens in periodontal disease?
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What is one primary effect of plaque biofilm on oral health?
What is one primary effect of plaque biofilm on oral health?
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Which of these factors is least likely to influence the progression of periodontal disease?
Which of these factors is least likely to influence the progression of periodontal disease?
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What is the primary characteristic of a biofilm?
What is the primary characteristic of a biofilm?
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What type of microorganisms are predominantly found in dental plaque?
What type of microorganisms are predominantly found in dental plaque?
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Which of the following statements best describes the equilibrium in stable gingivitis?
Which of the following statements best describes the equilibrium in stable gingivitis?
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What is a potential consequence of increased pathogenicity in biofilm microorganisms?
What is a potential consequence of increased pathogenicity in biofilm microorganisms?
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What is the significance of the extracellular slime layer in biofilms?
What is the significance of the extracellular slime layer in biofilms?
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Which type of bacteria is more likely to cause periodontal breakdown?
Which type of bacteria is more likely to cause periodontal breakdown?
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What condition may result from a compromised host defense?
What condition may result from a compromised host defense?
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What type of bacterium is Porphyromonas gingivalis?
What type of bacterium is Porphyromonas gingivalis?
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Which of the following best explains the term 'subgingival'?
Which of the following best explains the term 'subgingival'?
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What is a significant feature of Tannerella forsythia?
What is a significant feature of Tannerella forsythia?
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What is a characteristic of anaerobic bacteria found in dental plaque?
What is a characteristic of anaerobic bacteria found in dental plaque?
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What may disturb the equilibrium between dental plaque and host defenses in periodontal disease?
What may disturb the equilibrium between dental plaque and host defenses in periodontal disease?
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What role do gingipains play for Porphyromonas gingivalis?
What role do gingipains play for Porphyromonas gingivalis?
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What is a characteristic of Treponema denticola?
What is a characteristic of Treponema denticola?
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What impact does Aggregatibacter actinomycetemcomitans have in periodontal disease?
What impact does Aggregatibacter actinomycetemcomitans have in periodontal disease?
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Which feature is NOT associated with Porphyromonas gingivalis?
Which feature is NOT associated with Porphyromonas gingivalis?
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How does Tannerella forsythia affect connective tissues?
How does Tannerella forsythia affect connective tissues?
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What is a common trait of Treponema denticola in terms of immune response?
What is a common trait of Treponema denticola in terms of immune response?
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Which organism primarily uses GCF components for energy?
Which organism primarily uses GCF components for energy?
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What is a notable characteristic of Aggregatibacter actinomycetemcomitans in relation to motility?
What is a notable characteristic of Aggregatibacter actinomycetemcomitans in relation to motility?
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What is one of the virulence factors of Gram-negative coccoid bacillus?
What is one of the virulence factors of Gram-negative coccoid bacillus?
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Which hypothesis suggests that periodontal disease is due to a large number of bacteria in the gingival sulcus?
Which hypothesis suggests that periodontal disease is due to a large number of bacteria in the gingival sulcus?
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What is a key criticism of the Non-specific Plaque Hypothesis?
What is a key criticism of the Non-specific Plaque Hypothesis?
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As periodontal disease develops, what is observed in the composition of oral microbiota according to the Specific Plaque Hypothesis?
As periodontal disease develops, what is observed in the composition of oral microbiota according to the Specific Plaque Hypothesis?
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Which of the following bacteria is specifically identified with periodontal disease?
Which of the following bacteria is specifically identified with periodontal disease?
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What is a potential limitation of the Specific Plaque Hypothesis?
What is a potential limitation of the Specific Plaque Hypothesis?
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The Ecological Plaque Hypothesis focuses on which aspect of periodontal disease?
The Ecological Plaque Hypothesis focuses on which aspect of periodontal disease?
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What typically happens to fibroblasts and epithelial cells due to the toxins produced by Gram-negative baccillus?
What typically happens to fibroblasts and epithelial cells due to the toxins produced by Gram-negative baccillus?
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The Microbial Homeostasis-Host Response Hypothesis primarily addresses which aspect of periodontal disease?
The Microbial Homeostasis-Host Response Hypothesis primarily addresses which aspect of periodontal disease?
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Study Notes
Periodontal Disease and Microbiology
- Dental plaque is a biofilm, a community of inter-dependent organisms that grow on a surface
- The microbial composition of plaque includes:
- 700+ species of oral micro-organisms
- Gram-positive and Gram-negative bacteria
- Facultative and anaerobic bacteria
- In a healthy state there is dynamic equilibrium between dental plaque and the host defences.
- The equilibrium is disturbed in periodontal disease, possibly due to:
- Increased amount of plaque.
- Increased pathogenicity of the micro-organisms in the biofilm.
- Compromised host defence, such as in cases of immunocompromised individuals.
- Periodontal pathogens are the specific bacteria responsible for periodontal disease.
- About 12-15 types of bacteria have been shown to be particularly likely to cause periodontal breakdown.
Recognised Periodontal Pathogens
-
Porphyromonas gingivalis:
- Gram-negative bacillus, anaerobe, non-saccharolytic and non-motile.
- Produces gingipains, which allow the bacterium to utilise gingival crevicular fluid as a source of nutrients.
- Produces lipopolysaccharide (LPS), which can trigger haemogglutination and platelet aggregation, potentially linking to heart disease.
- Possesses fimbriae that allow tissue invasion, interfering with early polymorphonuclear leukocyte (PMN) response.
- Has the ability to break down collagen, leading to inflammation within gingival tissue.
-
Tannerella forsythia:
- Fusiform, Gram-negative anaerobe, difficult to culture.
- Certain phenotype, (prtH), is more commonly found in periodontitis.
- Produces proteases and apoptotic-inducing factor, contributing to cell death.
-
Treponema denticola:
- Motile bacterium, able to invade tissues.
- Utilises gingival crevicular fluid components as a source of energy for multiplication.
- Possesses adherence factors, leading to binding to fibroblasts.
- Can disrupt host defences by degrading cytokines and inducing their formation.
- May delay wound healing by hindering migration of PMNs.
- Found in periodontal lesions and severe periodontitis.
-
Aggregatibacter actinomycetemcomitans:
- Associated with aggressive periodontitis and treatment-resistant periodontitis.
- Gram-negative coccoid bacillus, not motile or anaerobic.
- Produces Leukotoxin, a virulence factor that can kill white blood cells (WBCs), disrupting host defences.
- Produces toxins that damage fibroblasts and epithelial cells.
- Produces proteases, including collagenase, leading to collagen breakdown.
- Can invade host epithelial cells.
Theories on the Role of Bacteria in Periodontal Disease
-
Non-Specific Plaque Hypothesis:
- This older theory attributes periodontal disease to the stagnation of plaque biofilm and large numbers of bacteria.
- The hypothesis suggests that the accumulation of plaque within the gingival sulcus leads to gingival inflammation and ultimately, periodontal destruction.
-
Specific Plaque/Microbial Shift Hypothesis:
- This theory postulates a shift in the oral microbiota as periodontal disease develops.
- It suggests a change from beneficial Gram-positive microbes to specific Gram-negative pathogens.
-
Ecological Plaque Hypothesis:
- This hypothesis proposes that periodontal disease develops due to changes in the environment created by the plaque biofilm.
- These changes favour the growth of specific pathogens, leading to disease.
-
Microbial Homeostasis- Host Response Hypothesis:
- This theory emphasises the role of the host immune response in periodontal disease.
- It suggests that while microbial changes occur, the dominant factor in tissue destruction is the uncontrolled host immune response.
-
Keystone Pathogen- Host Response Hypothesis:
- This contemporary hypothesis identifies specific "keystone" species that trigger a shift towards a dysbiotic biofilm community.
- The keystone species lead to uncontrolled host immune responses and resultant tissue damage.
Aetiology of Periodontal Disease
-
Multifactorial:
- Microbial factors: Periodontal pathogens play a crucial role.
-
Environmental factors:
- Smoking
- Poor oral hygiene
- Pre-existing pockets
- Plaque-retentive factors
-
Host defence factors:
- Defects in polymorphonuclear leukocyte (PMN) function.
- Certain inherited genotypes.
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Description
Test your knowledge on periodontal disease and its microbiology. This quiz covers the microbial composition of dental plaque, recognized periodontal pathogens, and the dynamics of a healthy oral environment versus disease. Understand the role of different bacteria and the factors influencing periodontal health.
