Defence Mechanism of Gingiva Quiz and Flashcards for Periodontal Immunology

Study Notes

Defence Mechanism of Gingiva

The gingival tissue is constantly subjected to mechanical and bacterial aggressions.
Resistance to these actions is provided by saliva, GCF, and epithelium.
The role of epithelium in defence depends on keratinization and turn over rate.
The principal cell is keratinocyte, which protects the deep structures and allows selective interchange with the oral environment.

Epithelial Defence Mechanism

The main function of the epithelium is to protect the deep structures and allow selective interchange with the oral environment.
This is achieved by proliferation and differentiation of keratinocytes.
Other proteins, keratinin and involucrin, form a chemically resistant structure.
The uppermost cells of the stratum spinosum contain dense granules known as keratinosomes or odland bodies.
These granules contain a large amount of acid phosphatase, which is related to the degree of keratinization.

Langerhans Cells

Langerhans cells are also present in the epithelium and are known as antigen-presenting cells.
They play an important role in immune reaction for lymphocytes.

Gingival Crevicular Fluid (GCF)

GCF is secreted by the sulcular epithelium and is an inflammatory exudate.
Methods of collection include twisted threads, absorbing paper strips, micropipettes, and intracrevicular washings.
The amount of fluid collected by paper strip is measured by staining and using a magnifying glass or electronic method.

Composition of GCF

GCF contains cellular elements, electrolytes, organic compounds, metabolic and bacterial products.
Cellular elements include epithelial cells, leukocytes, and bacteria, such as P. gingivalis, A. viscosus, and C. rectus.
Electrolytes include Na, Ca, K, and P.
Organic compounds include glucose, hexosamine, hexuronic acid, proteins, phosphorous, and lipids.
Metabolic and bacterial products include lactic acid, hydroxyproline, prostaglandins, endotoxins, and cytotoxic substances.

Antibacterial Factors in GCF

Acid phosphatase is the main source of AP in the crevicular area and is confined to the azurophil granules of PMNs.
AP is bacteriocidal and is also found in bacteria in the sulcus, such as Aa and Capnocytophaga.
Alkaline phosphatase is correlated with pocket depth and is present in PMNs and gram-negative bacteria.
Beta glucoronidase is found in the azurophilic or primary granules of PMNs and is also found in plaque bacteria.
Lysozyme is found in PMNs and contributes to pocket formation.

Enzymes in GCF

Hyaluronidase is an enzyme that degrades hyaluronic acid.
Proteolytic enzymes include cathepsin D, cathepsin G, elastase, collagenase, and plasminogen activators.

Cellular and Humoral Activity in GCF

The cellular immune response includes the appearance of cytokines, such as IL-1alpha and 1beta.
IL-1 is responsible for pocket formation and is known as the lethal cytokine.

Factors Affecting GCF

Circadian periodicity: gradual increase in GCF from 6AM to 10PM and thereafter it decreases.
Sex hormones: female sex hormones increase GCF flow.
Gingival crevicular fluid: increased GCF flow is a sign of inflammation.
Physiologic processes: chewing, mastication increases the flow of GCF.
Periodontal therapy: GCF flow increases during the healing period.
Smoking: smoking increases GCF flow.

Role of Saliva

Salivary secretion is protective in nature and maintains the oral epithelium in a physiologic state.
It exerts influence by mechanically cleaning exposed surfaces and buffering acids produced by bacteria.
Mastication increases saliva during physiologic processes.

Description

Learn about the defense mechanisms of the gingival tissue against mechanical and bacterial aggressions in periodontology. Explore the roles of saliva, GCF, and epithelium in protecting the oral structures and maintaining balance with the oral environment.