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Questions and Answers
What is the primary characteristic of periodontitis?
What is the primary characteristic of periodontitis?
What is the definition of plaque biofilm?
What is the definition of plaque biofilm?
Which of the following is NOT a factor contributing to the initiation of periodontitis?
Which of the following is NOT a factor contributing to the initiation of periodontitis?
Which cells are primarily involved in the immune response against periodontal disease?
Which cells are primarily involved in the immune response against periodontal disease?
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Which of the following cytokines is typically elevated during periodontal disease?
Which of the following cytokines is typically elevated during periodontal disease?
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What is one of the main roles of matrix metalloproteinases (MMPs) in the host response to periodontal disease?
What is one of the main roles of matrix metalloproteinases (MMPs) in the host response to periodontal disease?
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Which type of immune response is primarily involved in the defense against periodontal infections?
Which type of immune response is primarily involved in the defense against periodontal infections?
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Which of the following bacteria is commonly associated with the pathogenesis of periodontal disease?
Which of the following bacteria is commonly associated with the pathogenesis of periodontal disease?
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What is a common consequence of untreated periodontitis?
What is a common consequence of untreated periodontitis?
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What is one of the components of the intra-cellular matrix found in dental plaque biofilm?
What is one of the components of the intra-cellular matrix found in dental plaque biofilm?
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Which stage follows the initial colonization of the tooth surface in dental plaque formation?
Which stage follows the initial colonization of the tooth surface in dental plaque formation?
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Where is the junctional epithelium located?
Where is the junctional epithelium located?
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Which of the following bacteria is associated with periodontal disease?
Which of the following bacteria is associated with periodontal disease?
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What virulence factor of P. gingivalis helps resist host defenses?
What virulence factor of P. gingivalis helps resist host defenses?
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Which component is NOT found in the inorganic part of dental plaque biofilm?
Which component is NOT found in the inorganic part of dental plaque biofilm?
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Which of the following is a function of fimbrae in periodontal bacteria?
Which of the following is a function of fimbrae in periodontal bacteria?
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What characterizes mature biofilm in dental plaque?
What characterizes mature biofilm in dental plaque?
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What type of bacteria predominantly exists in the subgingival environment?
What type of bacteria predominantly exists in the subgingival environment?
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Which process involves the formation of an extracellular slime layer during biofilm development?
Which process involves the formation of an extracellular slime layer during biofilm development?
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What is the function of the junctional epithelium when it transforms into pocket-lining epithelium?
What is the function of the junctional epithelium when it transforms into pocket-lining epithelium?
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Which cells of the junctional epithelium are responsible for secreting cytokines during inflammation?
Which cells of the junctional epithelium are responsible for secreting cytokines during inflammation?
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What is the role of pro-inflammatory cytokines released during periodontitis?
What is the role of pro-inflammatory cytokines released during periodontitis?
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What is the primary role of saliva in the oral cavity?
What is the primary role of saliva in the oral cavity?
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Which of the following factors is involved in the initiation of periodontitis?
Which of the following factors is involved in the initiation of periodontitis?
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Which component of saliva primarily affects gram-positive bacteria?
Which component of saliva primarily affects gram-positive bacteria?
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What is the primary action of matrix metalloproteinases (MMPs) in periodontal disease?
What is the primary action of matrix metalloproteinases (MMPs) in periodontal disease?
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The adaptive immune response is primarily activated when which type of immunity is ineffective?
The adaptive immune response is primarily activated when which type of immunity is ineffective?
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What does the Non-specific Plaque Hypothesis suggest about periodontal disease?
What does the Non-specific Plaque Hypothesis suggest about periodontal disease?
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What type of immunity involves the production of antibodies?
What type of immunity involves the production of antibodies?
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What is a common misconception about the relationship between plaque and periodontal disease?
What is a common misconception about the relationship between plaque and periodontal disease?
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What is the name of the tissue macrophages that release host defenses?
What is the name of the tissue macrophages that release host defenses?
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Which cytokines are considered anti-inflammatory in the immune response?
Which cytokines are considered anti-inflammatory in the immune response?
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Which of the following is NOT a role of saliva?
Which of the following is NOT a role of saliva?
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Immunological memory is associated with which aspect of the immune response?
Immunological memory is associated with which aspect of the immune response?
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What type of pathogens does humoral immune response typically target?
What type of pathogens does humoral immune response typically target?
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What is the main function of B-cell lymphocytes in the humoral immune response?
What is the main function of B-cell lymphocytes in the humoral immune response?
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What role do epithelial Langerhans’ cells play in the immune response?
What role do epithelial Langerhans’ cells play in the immune response?
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How do antibodies like IgG and IgA contribute to the immune defense?
How do antibodies like IgG and IgA contribute to the immune defense?
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In the context of cell-mediated response, what do T-cells primarily utilize?
In the context of cell-mediated response, what do T-cells primarily utilize?
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What is the role of cytokines in the immune response to periodontitis?
What is the role of cytokines in the immune response to periodontitis?
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What type of mediator plays a chemical messenger role in periodontal disease?
What type of mediator plays a chemical messenger role in periodontal disease?
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How do T-helper (TH) cells assist B-cells in an immune response?
How do T-helper (TH) cells assist B-cells in an immune response?
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What is the primary focus of the humoral immune response?
What is the primary focus of the humoral immune response?
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What happens in the immune response during the shift from gingivitis to periodontitis?
What happens in the immune response during the shift from gingivitis to periodontitis?
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Which chemical mediator is released during inflammatory responses in periodontal disease?
Which chemical mediator is released during inflammatory responses in periodontal disease?
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Study Notes
Periodontitis
- Periodontitis is a microbial infection that triggers an inflammatory response within the periodontium, leading to the irreversible destruction of the supporting tissues (periodontal ligament and alveolar bone).
Plaque Biofilm
- Plaque biofilm is a community of microorganisms embedded in an extracellular glycocalyx (slime layer) that build up on the surfaces of the teeth.
- Plaque biofilm is composed of both organic and inorganic components.
- Organic components include polysaccharides, proteins, glycoproteins, and lipids.
- Inorganic components include calcium, sodium, phosphorous, and potassium.
- There are four stages of dental plaque biofilm formation.
- Initial attachment of bacteria to the pellicle.
- Initial colonization of the tooth surface - new bacteria join.
- Secondary colonization: Extracellular slime layer formation.
- Mature biofilm - mushroom shaped colonies.
Tissues of the Periodontium
- The gingival epithelium is composed of three distinct parts:
- Oral epithelium - covering the free and attached gingivae.
- Sulcular epithelium - lines the sulcus.
- Junctional epithelium - at the base of the sulcus.
- The four tissues of the periodontium include:
- Gingivae.
- Periodontal ligament.
- Root cementum.
- Alveolar bone.
Bacteria Associated with Periodontal Disease
- The subgingival environment supports mainly anaerobic bacteria.
- Several bacteria species are associated with periodontal disease:
- Porphyromonas gingivalis.
- Aggregatibacter actinomycetemcomitans.
- Treponema denticola.
- Tannerella forsythia.
- Fusobacterium nucleatum.
- Prevotella intermedia.
- These bacteria produce several virulence factors including:
- Carbohydrate capsule.
- Gingipains.
- Lipopolysaccharide (LPS).
- Haemogglutinin and platelet aggregators.
- Fimbrae.
Host Defenses
- Saliva plays a critical role in oral health.
- Prevents drying of oral tissues
- Antimicrobial effects - swallowing bacteria and secretion of salivary IgA (influences bacterial attachment).
- Peroxidase, lysosome and lactoferrin - mainly affect gram positive bacteria (supragingival role mainly).
- Adaptive immunity, also known as acquired or specific immune response, is activated when innate immunity is ineffective in eliminating pathogens.
- It is highly specific to a particular pathogen by recognizing its antigen.
- It has immunological memory.
- Adaptive immunity utilizes two main mechanisms:
- Humoral immunity (antibody response).
- Cell-mediated immunity.
- Humoral immune responses produce antibodies against agents existing in the humors (extracellularly).
- Epithelial Langerhans' Cells present antigenic parts from pathogens to circulating lymphocytes, stimulating clonal expansion after recognizing the specific antigen.
- B-cell lymphocytes differentiate into plasma cells, which release antibodies against the specific antigen.
- Antibody IgG and IgA productions are thought to be protective.
- Locally or systemically produced antibodies clump and prevent microorganisms from adhering to the epithelium; work with complement to lyse bacteria; work with neutrophils for opsonization (marking) and phagocytosis.
- Cell-mediated response does not require the use of antibodies—it uses its own T-cell receptor.
- Antigen presentation via Langerhans'/dendritic cells.
- TH cells: produce cytokines; assist B-cell differentiation into plasma cells; activate neutrophils and macrophages.
- Progression from gingivitis to periodontitis elicits a shift from T-cell to B-cell lesions.
Chemical Mediators
- Cytokines are small proteins crucial in controlling the growth and the activity of immune system cells and blood cells. They aid in the inflammatory responses in various ways.
- Pro-inflammatory cytokines (e.g., IL-1, IL-6, TNF-α) are released in response to pathogens, contributing to the destruction of periodontal tissues.
- Anti-inflammatory cytokines (e.g., IL-4 and IL-10) help to regulate the inflammatory process.
- Prostaglandins, such as PGE_2, are involved in bone resorption, neutrophil chemotaxis, vascular permeability, and dilation.
- Matrix metalloproteinases (MMPs) are pro-inflammatory enzymes that degrade connective tissues.
Factors Contributing to the Initiation of Periodontitis
- In health and stable gingivitis, there is a dynamic equilibrium between dental plaque and the host defenses. This equilibrium is disturbed in periodontitis, tipping in favor of tissue damage. Several factors contribute to this shift:
- An increased amount of plaque.
- Increased pathogenicity of the microorganisms in the biofilm due to their changing composition.
- Compromised host defense.
Theories on the Role of Bacteria in Periodontal Disease
-
Non-specific Plaque Hypothesis: This theory proposed that the stagnation of plaque biofilm and the numbers of bacteria within would lead to inflammation in the adjacent gingival sulcus, leading to periodontium tissue destruction.
- Issues: This is a simplistic theory. Most gingivitis cases do not progress to periodontitis, and some patients with light traces of biofilm may suffer from periodontitis, while other sites remain unaffected.
-
Specific Plaque Hypothesis: This theory suggests that specific bacteria within the plaque biofilm are the primary cause of periodontitis.
- Issues: This theory has been challenged by the fact that many individuals with high levels of "periodontopathic" bacteria do not develop periodontitis, and many individuals with periodontal disease lack those specific bacteria.
-
Keystone Pathogen-Host Response Hypothesis: This theory proposes that certain bacteria, called "keystone pathogens," act as initiators that disrupt the balance of the oral microbiome, leading to a shift towards a dysbiotic community. This dysbiotic community then triggers an excessive host inflammatory response that contributes to periodontal disease.
- Support: This hypothesis is supported by the fact that individuals with periodontitis often have a dysbiotic microbiome, and that the host's immune response plays a crucial role in the progression of the disease.
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Description
Test your knowledge on periodontitis and the formation of dental plaque biofilms. This quiz covers the microbial infections, inflammatory responses, and the various stages of plaque biofilm formation. Perfect for dental students and professionals alike.
