Host Response

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Questions and Answers

What primarily characterizes the established lesion in connective tissue?

Presence of plasma cells (correct)

High levels of neutrophils

Thick epithelial ridges

Lymphocyte dominance

Which immune cells are involved in combating bacteria in the sulcus?

B cells exclusively

Only lymphocytes

Macrophages and PMNs (correct)

Only plasma cells

What role do cytokines play in the immune response during established gingivitis?

They reduce inflammation

They promote healing of tissue

They recruit additional immune cells (correct)

They cause osteoclast activation

How does the junctional epithelium change during the progression of gingivitis?

It loosens its attachment and transforms into pocket epithelium Signup and view all the answers

What initiates the host immune response during the bacterial accumulation phase?

Gram-negative bacteria and their metabolic products Signup and view all the answers

After how many days is established gingivitis generally observed following plaque biofilm accumulation?

21 days Signup and view all the answers

What is the potential outcome if established gingivitis is not controlled in susceptible individuals?

It may progress to periodontitis Signup and view all the answers

What is the primary role of PMNs during the bacterial accumulation phase?

To pass from blood vessels into the gingival connective tissue Signup and view all the answers

What clinical feature is indicative of the initial lesion phase?

Healthy appearance of the gingiva Signup and view all the answers

What additional substances are produced by macrophages exposed to gram-negative bacteria?

Cytokines, PGE2, and MMPs Signup and view all the answers

Which feature is indicative of gingivitis as it progresses into an established lesion?

Decreased collagen production Signup and view all the answers

Which of the following statements about PMNs in early gingivitis is correct?

They form a wall of cells to defend against the biofilm. Signup and view all the answers

How does the complement system relate to the host immune response during bacterial accumulation?

It enhances the recognition of bacteria by immune cells. Signup and view all the answers

What role do macrophages play in the immune response during tissue destruction?

They release biochemical mediators to recruit additional immune cells. Signup and view all the answers

During the early phase of gingivitis, what percentage of collagen loss is typically observed?

60% to 70% Signup and view all the answers

What occurs if the bacterial infection is not controlled after the initial lesion phase?

Development of early gingivitis Signup and view all the answers

What effect does increased permeability of blood vessels have during early gingivitis?

Increased movement of PMNs to the infection site Signup and view all the answers

Which cellular feature predominantly characterizes an early lesion phase of gingivitis?

Presence of epithelial ridges Signup and view all the answers

What is the primary consequence of cytokine release by junctional epithelial cells in early gingivitis?

Attraction of additional PMNs to the site of infection Signup and view all the answers

What is the primary consequence if the host immune response fails during the early lesions of gingivitis?

Progression to established gingivitis Signup and view all the answers

What triggers the epithelial cells to secrete more cytokines during the gingivitis process?

Presence of high subgingival bacterial numbers Signup and view all the answers

Which feature is a clinical observation of early gingivitis?

Edema and redness of gingival marginal tissue Signup and view all the answers

What is the result of effective plaque biofilm control in response to gingivitis?

Restoration of health through tissue repair Signup and view all the answers

What primarily characterizes the established lesions of gingivitis?

Subgingival plaque biofilm extension and bacterial infiltration Signup and view all the answers

What role does lipopolysaccharide (LPS) play in periodontal disease?

It initiates inflammation in periodontal tissues. Signup and view all the answers

Which bacteria has the ability to invade host tissues in periodontal disease?

Porphyromonas gingivalis Signup and view all the answers

What impact does smoking have on the host immune response.

It negatively affects T- and B-lymphocyte responses. Signup and view all the answers

How do genetic factors contribute to periodontal disease?

They are associated with aggressive forms of the disease. Signup and view all the answers

Which of the following is a consequence of diabetes mellitus on the host immune response in periodontal disease?

Increased levels of tumor necrosis factor-α. Signup and view all the answers

What is the effect of enzymes produced by periodontal bacteria?

They degrade host proteins integral to the periodontium. Signup and view all the answers

Which acquired factor is a known risk for periodontal diseases?

Diabetes mellitus Signup and view all the answers

What is a notable effect of genetic variations in periodontal disease susceptibility?

They can modify the immune response to plaque biofilm. Signup and view all the answers

What occurs as a result of the chronic immune response to periodontal infection?

Destruction of periodontal tissues Signup and view all the answers

Which cellular component is primarily responsible for the destruction of the extracellular matrix of the gingiva?

MMPs Signup and view all the answers

What is the main outcome of the host's immune response during advanced periodontal disease?

Tissue destruction Signup and view all the answers

Which cells migrate apically on the root surface leading to the formation of a periodontal pocket?

Cells of the junctional epithelium Signup and view all the answers

What characterizes the advanced lesion phase of periodontitis?

Periodontal pocket formation and tooth mobility Signup and view all the answers

What role do osteoclasts play in periodontal disease progression?

Resorbing the crest of the alveolar bone Signup and view all the answers

Which of the following statements about chronic inflammation in periodontitis is true?

It causes more damage than the bacterial infection itself. Signup and view all the answers

What is a hallmark of periodontitis?

Irreversible tissue damage Signup and view all the answers

Study Notes

Host Immune Response to Plaque Biofilm

Periodontal disease is a bacterial infection that triggers an inflammatory response in periodontal tissues.
Bacteria, although essential, are not alone responsible for tissue destruction. The body's response to bacteria in plaque biofilm is the main cause of damage.
The host response aims to defend against bacteria in plaque biofilm, but doesn't prioritize preserving the tooth itself.

Factors Enhancing Microbial Challenge

Bacteria are essential for periodontal disease initiation and progression.
Virulence factors enable biofilm bacteria to colonize and harm tissues. These can be structural or produced substances.
- LPS (lipopolysaccharide): A component of gram-negative bacteria, can initiate inflammation.
- Tissue invasion: Some bacteria can invade epithelial cells.
- Enzyme production: Collagenases and proteases directly degrade host proteins.

Factors Affecting the Host Immune Response

Genetic, environmental, and acquired factors affect host susceptibility to periodontal disease. They influence response or tissue metabolism.
- Genetic factors: Link to periodontal disease, studied in twins and families. Conditions like Papillon-Lefèvre syndrome and LAD are associated with aggressive periodontal disease.
- Environmental factors: Smoking significantly impacts the immune and inflammatory systems, decreasing PMN phagocytic capacity, altering blood vessel health, & affecting lymphocyte response.
- Acquired Factors: Diabetes mellitus affects host response by reducing PMN function and increasing inflammation markers like IL-1, TNF-α, and PGE2, reducing fibroblasts' proliferation.

Inflammation: A Protective, Potentially Harmful Host Response

Acute inflammation: The body's immediate defense against microbial invasion.
- Involves immune cells (PMNs, macrophages, T/B lymphocytes, fibroblasts, epithelial cells) and biochemical mediators.
- Serves as a first line of defense, removing stimuli, repairing tissues, and creating a favorable environment for repair.
- Resolution (catabasis) is essential: successful resolution prevents harmful effects. Issues with resolution can lead to chronic inflammation.

Inflammatory Biochemical Mediators

Cytokines (released by immune cells): Crucial regulators of cell behaviour. Can be both tissue-protective or -destructive and critical to periodontitis. Key examples include IL-1, IL-6, IL-8, and TNF-α
Prostaglandins (PGE2): Important inflammatory mediators derived from fatty acids, play a role in bone destruction in periodontitis, affect blood vessel permeability, and trigger osteoclast activity.
Matrix Metalloproteinases (MMPs): A family of proteolytic enzymes that break down connective tissue matrix. Their role in periodontitis is substantial and tissue destructive when their control is impaired.
The balance between MMPs and their inhibitors (TIMPs) is crucial for healthy connective tissue. Disruption leads to pathologic breakdown.

Tissue Destruction by Biochemical Mediators

Each mediator plays a specific role in the local damage to tissues during periodontitis. The table directly correlates the inflammatory mediators with the type of local tissue affects observed in the inflammation/infection response. This demonstrates the multifactoral impact of these events, as these factors impact more than a single tissue.

Current Theory of Pathogenesis

Periodontal disease development is complex and multifactorial.
Microbial challenge activates the host response.
Genetic, environmental, and acquired factors impact the immunoinflammatory response.
Inflammatory mediators contribute to tissue destruction.
Resolution of inflammation and returning to homeostasis is also crucial to preventing the negative effects of inflammation.

Histologic Stages of Periodontal Disease

Bacterial accumulation (initial lesion): Early bacterial colonization, initiating host immune response.
Early gingivitis (early lesion): Increasing bacterial challenge, escalating PMN and macrophage activity affecting the gingival connective tissue, early tissue changes are apparent.
Established gingivitis (established lesion): Deeper bacterial penetration, more severe tissue inflammation and destruction (including collagen loss), and visible clinical changes.
Periodontitis (advanced lesion): Severe tissue damage, formation of pockets, irreversible bone loss, as well as clinical signs. Factors like genetic and environmental conditions and ineffective immune responses potentially contribute to disease progression.

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