37. Physiology of saliva. Role of gingival crevicular fluid in the oral physiology.

PHYSIOLOGY OF SALIVA. ROLE OF GINGIVAL CREVICULAR FLUID IN ORAL PHYSIOLOGY

PHYSIOLOGY OF SALIVA

• Saliva is a complex fluid that, in health, almost continuously bathes part of exposed teeth within oral cavity
• Saliva represents the immediate environment of the tooth
• Produced by parotid, submandibular and sublingual glands and several minor salivary glands
• Factors affecting viscosity of saliva:
• Presence of mucins
• Salivary flow
• pH
• Whole saliva includes secretion from glands, products of a non-salivary nature, exfoliated epithelial and immune cells, gingival clavicular fluid and nutrients and MOs Microorganisms

PROTECTION THROUGH

• Clearance
• Lubrication
• Thermal/chemical insulation
• Pellicle formation
• Tannin binding

FUNCTIONS OF SALIVA

• PROTECTION/ CLEARANCE:
• Provides a washing action that flushes away non-adherent bacteria and other debris
• Clears sugars in order to limit their availability to acidogenic plaque MOs
• Mucins provide lubrication to avoid tissues from adhering to one another and allows them to slide easily over one another
• Mucins provide a barrier against noxious stimuli, microbial toxins and minor trauma
• LUBRICATION:
• Coats food and oral soft and hard tissues to allow food to travel through the digestive system surfaces with minimal infections
• MAINTENANCE OF MUCOUS (MEMBRANE INTEGRITY):
• Salivary mucins possess rheological properties that include low solubility, high viscosity, elasticity and adhesiveness
• Provides an effective barrier against dessication and environmental factors
• Protects underlying cells from sudden changes in osmotic pressure
• 2nd line of defence against procrease activity- cysteine containing phosphoprotein
• TISSUE REPAIR:
• Helps with wound healing and regeneration
• Active constituents of saliva (growth factors, biologically active peptides and proteins)
• Promotes tissue growth and differentiation, wound healing and other beneficial effects
• DILUTION AND CLEARANCE:
• Saliva dilutes and eliminates dietary sugars and acids
• Swallowing frequency and salivary flow rate controls this process
• ANTIMICROBIAL ACTIVITY:
• Active constituents of saliva (mucins, secretory IgA, peroxidase, lysozyme) act as a physical barrier and are associated with immune and non-immune defences
• Proteins (including lysozyme, lactoferrin, peroxidase, etc) have anti-microbial, bacterial/viral/fungal activities as it disrupts cellular or mitochondrial functions of MOs
• ANTIFUNGAL ACTIVITY:
• Parotid fluid has an antifungal capacity, reflecting properties of both neutral and basic histidine rich peptides
• ANTIVIRAL ACTIVITY:
• Secretory IgA can directly neutralise viruses and so can mucins
• Major function of saliva is to prevent the establishment of unusual species
• BUFFERING CAPACITY:
• Provides resistance to pH changes at an arbitrary point
• There are 3 buffer systems:
• Carbonic acid and bicarbonate
• Phosphate
• Protein
• Active constituents, urea and ammonia have functions of pH maintenance and acid neutralization
• TOOTH INTEGRITY: