Gingival Crevicular Fluid Periodontics Important Question And Answers

Gingival crevicular fulid

Gingival crevicular fluid (GCF) has been recognized for over a hundred years. Brill and Engelberg described that increased permeability of vessels underlying junctional epithelium and sulcular epithelium resulted in the production of GCF.

• Alfonso and Pashley reported that GCF could simply be the interstitial fluid that appears in the crevice as a result of an osmotic gradient.
• In effect, therefore, GCF may be described as a transudate in normal conditions but the bulk of the fluid observed in periodontal diseases constitutes an inflammatory exudate.

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Question 1: How is the GCF produced?
Answer:

• Gingival crevicular fluid is obtained from the gingival plexus of blood vessels in the gingival connective tissue, subjacent to the epithelium lining of the dentogingival space.
• GCF production is governed by the passage of fluid from capillaries into the tissues (capillary filtrate) and the removal of this fluid by the lymphatic system (lymphatic uptake).
• When the rate of capillary filtrate exceeds lymphatic uptake fluid collects as edema and/or gets expressed as GCF.

Properties Of Gingival Crevicular Fluid

• Flushing effect
• Isolation effect
• Nutrient effect
• Diagnostic potential

Question 2: Describe the methods of collection and estimation of GCF.
Answer:

The placement of the filter paper strip about the sulcus of the pocket is important as it determines the nature of GCF collected to an extent.

1. Extracurricular

• In this technique, the filter paper strip is closely adapted to the labial surface of the tooth without being inserted into the crevice.

2. Intracrevicular

It is the most popular method of collecting GCF. In this technique, filter paper strips are inserted inside the gingival crevice at different depths from the gingival margin to the base of the crevice, until minimal resistance is encountered. A variation of this technique involves placement of the paper strip at the entrance of the crevice in order to avoid irritation of the crevicular epithelium thereby influencing the GCF flow.

• Absorbent paper strips
• Micropipettes
• Preweighed threads

 Twisted Preweighed Threads

Threads are placed around the gingival sulcus and the amount of GCF collected is measured by reweighing the thread after GCF collection.

Micropipettes

They enable the collection of GCF by capillary action. Capillary tubes of known diameter and size are positioned at the entrance of the gingival sulcus to enable GCF to migrate into the tube by capillary action.

• As the diameter of the tube is known, the amount of GCF collected can be estimated by measuring the distance GCF has migrated in the tube.
• After the distance is estimated, the contents of the tube are eluted into a small container for storage and further analysis.
• The limitation of this technique is that it needs a long collecting period and the viscosity of the fluid is sometimes high, making aspiration difficult.

Gingival Washings

• This technique uses an appliance consisting of a hard acrylic plate covering maxillary gingiva containing grooves following the gingival margins attached to four collection tubes.
• The crevicular area is rinsed with saline and the washing is collected into the tube using peristaltic pumps. It is a complex procedure and the GCF collected may be much diluted.

Methods Of Estimating Gingival Crevicular Fluid

• Preweighed threads
  • Change in the weight of the threads after absorbing GCF. Weighing the threads before and after collection requires a very sensitive balance to estimate the fluid collected from the crevice.
• Micropipettes 
  • The distance the GCF has migrated in a certain period when inserted in a certain depth into the sulcus.
• Filter paper strips
  • A 1.5 mm strip, inserted 1mm into the crevice absorbs only 0.1 mg of fluid in 3 minutes.
  • Staining with ninhydrin produces a purple color which enables to measure the;
    • The distance the flid has migrated up the strip
    • Area of filter paper wetted by GCF sample.

 

Periotron

• It is an electronic device that measures the change in capacitance across the wetted strip. It measures the effect of the electric current flow of the wetted paper strip.
• This change is converted to a digital readout which can be correlated with the volume of GCF. Periotron provides accurate dimensions of GCF volume and facilitates subsequent laboratory investigation of the sample.
• Periotron is available in several models: 600, 6000, and 8000. Earlier versions of Periotron had the limitation of inability to measure GCF >1.0 µL.
• Periotron 8000 is the advanced version with provides automatic calibration to true volume, an interface with a computer for storage, retrieval, and display of data, and measure large volumes of fluid (up to 3 µL)

Question 3. What are the functions of GCF?
Answer:

• The outflow of GCF clears dentogingival space of nonadherent microbes, which also decreases their toxins and metabolic byproducts.
• GCF contains an array of antimicrobial components and enzymes that are directly delivered to the site of bacterial colonization thus exerting antibody activity in defense of gingiva.
• PMNs which form the primary defense system present in GCF, defend it against bacterial invasion through
• phagocytic and bactericidal mechanisms.
• PMN activity releases granules that disengage plaque adherent to the tooth.
• Contains plasma proteins that may help the adhesion of gingival epithelium to the tooth.

Signifiance of GCF Flow

• GCF flow is expected to increase with the increase in inflammation.
• GCF flow decreases progressively in parallel with clinical changes post-periodontal treatment.
• GCF flow also follows a circadian rhythm. There is a gradual increase in the flow of GCF early in the morning and a decrease afterward.
• GCF flow increases during pregnancy, puberty, and menstruation. This is probably because of the effect of female sex hormones which increase the vascular permeability of the tissues.
• Systemically administered drugs were found to be expressed in GCF, especially drugs like tetracycline and metronidazole. The concentration of these drugs in GCF was found to be higher than that in saliva.
• Smoking produces an immediate transient but marked increase in GCF flow.

Question4: Describe the composition of GCF
Answer:

The GCF comprises of an admixture of molecules originating from blood, host tissue, and plaque. It contains a diverse population of cells which includes bacteria from plaque, desquamated epithelial cells from the sulcus, leucocytes, and RBCs.

Epithelial Cells

The intense mitotic activity in junctional and sulcular epithelium is attributed to the presence of desquamated epithelial cells in the gingival crevice and therefore in GCF. The dentogingival junction also enables the entry of bacterial pathogens into the gingival epithelium and connective tissue and allows the first line of defense mechanism established there. Hence remnants of epithelial cells with the adhered microorganisms are found in GCF.

Leucocytes

• The presence of leucocytes in GCF was confimed in 1958. PMN is the predominant inflammatory cell in GCF.
• Most of the crevicular PMNs are viable cells capable of protecting the dentogingival junction and preventing apical extension of subgingival plaque despite decreased efficiency.
• Crevicular PMNs in diseased sites show decreased phagocytic capability and decreased migration when compared to healthy sites, which shows that functionality varies with the severity of inflammation.
• Attstrom in 1970 showed that the ratio of T cell and B cell was 1: 2.7 as opposed to the differentials in peripheral blood.

Bacteria

Microorganisms are found free-floating/attached to epithelial cells in GCF. The actual number of microorganisms in GCF is not associated with the number in plaque mass.

The constituents of gingival crevicular fluid can be classified according to their source of origin as follows:

• Products of microbial plaque
• Products of tissue breakdown
• Products of host cells
• Products of host immunity.

Products of Microbial Plaque

• Endotoxins: Like bacterial LPS
• Enzymes: Proteinases, MMPs, hyaluronidases
• End products of microbial metabolism: Short chain fatty acids, ammonia, amines, etc.

Tissue Breakdown Products

• Collagens- type 1, type 2, hydroxyproline
• Proteoglycans and hyaluronic acid- dermatan sulfate, heparin sulfate, chondroitin sulfate
• ECM components- laminin, fibronectin
• Enzymes- myeloperoxidase, lactoferrin.

Products of Host Cells

• Collagenase
• Aspartate aminotransferase (AST)
• Alkaline phosphatase (ALP)
• Elastase
• Cathepsins
• Lysozyme
• Lactoferrin
• Hyaluronidase, B glucuronidase, and arylsulfatase.

Products of Host Immunity

• Immunoglobulins- IgA, IgG, IgM
• Complements
• Cytokines: Interleukin (IL) -1, IL-4, IL-6, IL-10, TNF-α
• Arachidonic acid metabolites: Prostaglandins (PG E2).

Question 5:Write a note on GCF in the diagnosis of periodontal health and disease.
Answer:

Gingival crevicular fluid traverses through inflamed periodontal tissues and in this process, biological molecular markers are gathered from the surrounding areas and are finally presented into the sulcus.

• Thus the components of GCF can be used as a biomarker in the diagnosis of periodontal disease.
• It is difficult to pinpoint the presence or absence of one single component as a definitive marker in defining the clinical state of the periodontium.
• GCF sampling methods capture inflammatory and connective tissue breakdown mediators accurately, especially those of soft-tissue inflammatory events and a few specific biomarkers of alveolar bone destruction.

GCF is collected and its components are analyzed:

• To identify periodontal health and the presence of any disease
• To identify the severity of the disease
• To devise a treatment plan for the patient based on disease activity and evaluate the post-treatment.

Commercially viable diagnostic kits use GCF as a diagnostic marker. Some of the available kits are:

• Periogard: Aspartate aminotransferase (AST)
• Pocket watch: Aspartate aminotransferase (AST)
• Prognostic: Elastase
• Periocheck: Neutral proteinase.