OE L23 Gingival Crevicular Fluid Flashcards
What is gingival crevicular fluid?
Fluid derived from underlying periodontal tissues which gathers at the gingival crevice. Distinct from saliva.
How can GCF be collected?
- Capillary tubes
- Filter strips
- Gingival washing
How is GCF regarded in health vs in diseased states?
GCF in health = transudate
GCF in disease = exudate
What is flow rate of GCF determined by?
GCF flow rate is proportional to the degree of gingival inflammation.
Healthy = low rate
Inflamed = high rate
What are the constituents of GCF derived from?
- Plasma
- Interstitial fluid
- Microbial dental plaque
- Host inflammatory cells
- Host tissue cells (fibroblasts)
What is the transudate caused by?
Distrubances in hydrostatic or colloid osmotic pressure- not by inflammation.
What is the average flow rate of transudate?
0.05-0.2 ul per min
What pressures can increase flow of GCF?
- Mastication
- Tooth brushing
Only cause small increases in flow.
How does fluid pass from the sulcus to the crevice?
Intercellular routes across the wall of the gingival epithelium. Movement is beleived to be osmotic mediated.
GCF flow in health is determined by what 5 factors?
- Passage of interstitial fluid from capillaries to gingival tissues
- Removal of fluid by lymphatic system
- Filtration coefficient of junctional and sulcular epithlium
- Differences in osmotic pressure (created by presence of plaque products within sulcus)
- Differences in hydrostatic pressure of interstitial fluid and sulcular fluid e.g. from brushing or mastication
How does the microbial population affect GCF?
Microbial population in the gingival crevice could produce products which create an osmotic flow of liquid into the sulcus, in order to dilute the presence of such products.
Effectively pushes them out and into the oral cavity.
How does gingival inflammation cause exudate production?
- Higher levels of plaque create greater osmotic gradient
- Fluid flow rate increased
- Loosening of epithelial cells in gingival epithelium, BM breakdown due to action of inflammatory cells, fluid flows across more easily
- Capillaries become fenestrated due to host immune response and increases hydrostatic pressure
- Fenestrated capillaries allow increased inflammatory cells in tissues
Describe the composition of GCF.
- Derived from interstitial fluid of underlying periodontal tissues
- Greater amount of inorganic components compared to saliva e.g. Na, Ca, P
What are the main functions of GCF?
- Protection of teeth and gingival tissues by washing away potentially harmful bacterial products away from the gingival sulcus
- Contains anitbacterial substances
- High calcium concentration allows pellicle proteins to bind to tooth surface (semi-permeable barrier between enamel and bacteria)
What are the negative consequences of high Ca content of GCF?
- Enhances salivary protein precipitation which could allow increased attachement of bacteria
- Calculus formation: mineralisation of dental plaque, will be particularly damaging if present subgingivally
What organic molecules are present in the transudate?
In ‘health’, low levels of the following are present:
- amino acids
- prostaglandin E
- fragments of ECM components
- cytokines and growth facotrs (tissue remodelling and repair)
In diseased states, there are increased organic components that are involved in the degradation of underlying connective tissues.
What key proteins are found in GCF?
Serum derived proteins.
What 5 serum derived proteins can be found in GCF?
- Serum albumin (acts as an antioxidant, neutralises reactive oxygen and nitrogen species produced by macrophages and neutrophils)
- IgA, IgG, IgM (remove virulence factors produced by bacteria)
- Fibrinogen (blood clot formation)
- Complement cascade components (cause release of lysosomal enzymes from leucocytes and mediate cell lysis)
- Protease inhibtors (maintain tissue health)
Give examples of protease inhibitors.
- α1 anti-trypsin
- α2 macroglobulin
- α1 anti-chymotrypsin
What metabolic components from bacteria may be found in GCF?
- Urea
- Lactic acid
- Hydorgen sulphate
- Lipopolysaccharides
- Bacterial enzymes e.g. acid phosphotase, lysozyme, hyaluronidase
Give example of enzymes found in GCF derived from host inflammatory cells and resident CT cells.
- Alkaline phosphotase
- Cathepsin D (not correlated with later stages of perio tissue destruction)
- Elastase (correlated with gingivitis)
- Cathepsin G
- Collagenases (associated with active destruction of underlying CTs)
Why are biomarkers of GCF so valuable?
- Can be collected through non-invasive means
- Site specific
- Tells us what has happened to the tissue
- Provides info regarding mechansisms of perio tissue destruction
- Potential prognostic/diagnostic indicators of disease progression
- Could be used to measure response to therapy
Give examples of biomarkers of GCF and their use.
- Lipopolysaccharides: correlation with gignival inflammation
- Trypsin-like proteases: correlaton with P.gingivalis and T.denticola in gignival pockets - did not correlate or predict levels of enhanced perio tissue destruction
- Bacterial colleganses: correlation with levels of bacteria in perio pockets and attachment loss at high levels
Overall use for bacterial classifcation and treatment choice. Not a predictor of active tissue destrcution.
What are PMNs?
Polymorphonucleocytes.
One of the first cells types to invade tissue during inflammation, PMNs are biomarkers of inflammation.
Describe IgG as a biomarker.
IgG to specific antigens can identify different forms of periodontitis.
Describe IL-1 as a biomarker.
A cytokine with a positive correlation with active tissue destruction.
Describe prostaglandin E2 as a biomarker.
Positive correlation associated with adult periodontitis.
Describe OPG/RANKL as a biomarker.
High RANKL ratio indicates bone resoprtion. RANKL stimulates differentiation of osteoclasts (OPG inhibits RANKL).
What connective tissue components of GCF may be biomarkers for advanced stages of periodontal tissue destruction?
- Collagens (hydroxyproline, pyridinoline and deoxypyridinoline)
- Proteoglycan (chondroitin sulphate)
- Osteocalcin
Describe pyridinoline and hydroxypyrilinodine as biomarkers.
Crosslinks for collagen.
Increase in these relates to destruction of alveolar bone.
Describe chondroitin sulphate as a biomarker.
Linked to adult periodontitis and in orthodontic tooth movement where there are high levels of active destruction of alveolar bone.
Not correlated with gingivitis.
