SALIVA

1. SALIVA Seminar Stomatology

2. MAJOR FUNCTIONS OF SALIVA • Solvent • Buffering • Lubrication • Remineralization • Digestion • Anti-bacterial • Anti-fungal • Temperature regulation • Production of growth factors and other regulatory peptides

3. A CONSIDERABLE VOLUME OF SALIVA IS PRODUCED OVER A DAY • 0.5 to 1.5 liter of fluid is secreted in a day • This represents about 1/5 of the total plasma volume • This fluid is not lost as most of it is swallowed and reabsorbed by the gut • Parotis, submandibularis, sublingualis

4. THE SECRETORY UNIT The basic building block of all salivary glands • Saliva formed in acini flows down DUCTS to empty into the oral cavity. • ACINI - water and ions derived from plasma

5. TWO STAGE HYPOTHESIS OF SALIVA FORMATION Most proteins Na+ Cl-resorbed Hypotonic final saliva into mouth Water & electrolytes Someproteinselectrolytes K+secreted Isotonic primary saliva

6. Inorganic components Saliva compositon

7. Calcium and phosphate • Help to prevent dissolution of dental enamel • Calcium • 1,4 mmol/l (1,7 mmol/l in stimulated saliva) • only cca 50% in ionic form • sublingual > submandibular > parotis • Phosphate • 6 mmol/l (4 mmol/l in stimulated saliva) • 90% in ionic form • pH around 6 - hydroxyapatite is unlikely to dissolve • Increase of pH - precipitation of calcium salts => dental calculus

8. Hydrogen carbonate • Buffer • Low in unstimulated saliva, increases with flow rate • Pushes pH of stimulated saliva up to 8 • pH 5,6 critical for dissolution of enamel • Defence against acids produced by cariogenic bacteria • Derived actively from CO2 by carbonic anhydrase

9. Other ions • Fluoride • Low concentration, similar to plasma • Thiocyanate • Antibacterial (oxidated to hypothiocyanite OSCN- by active oxygen produced from bacterial peroxides by lactoperoxidase) • Higher conc. => lower incidence of caries • Smokers - increased conc. • Sodium, potassium, chloride • Lead, cadmium, copper • May reflect systemic concentrations - diagnostics

10. Concentration (mM) FLOW RATE ml/min

11. Organic components Saliva composition

12. Organic components of saliva • Mucins • Proline-rich proteins • Amylase • Lipase • Peroxidase • Lysozyme • Lactoferrin • sIgA • Histatins • Statherin • Blood group substances, sugars, steroid hormones, amino acids, ammonia, urea

13. Multifunctionality Amylases, Cystatins, Histatins, Mucins, Peroxidases Carbonic anhydrases, Histatins Anti- Bacterial Buffering Amylases, Mucins, Lipase Cystatins, Mucins Anti- Viral Digestion Salivary Functions Mineral- ization Anti- Fungal Cystatins, Histatins, Proline- rich proteins, Statherins Histatins Lubricat- ion &Visco- elasticity Tissue Coating Amylases, Cystatins, Mucins, Proline-rich proteins, Statherins Mucins, Statherins adapted from M.J. Levine, 1993

14. Mucins • Lubrication • Glycoproteins - protein core with many oligosaccharide side chains attached by O-glycosidic bond • More than 40% of carbohydrates • Hydrophillic, entraining water (resists dehydration) • Unique rheological properties (e.g., high elasticity, adhesiveness, and low solubility) • Two major mucins (MG1 and MG2)

15. Amylases • Calcium metalloenzyme • Hydrolyzes (1-4) bonds of starches such as amylose and amylopectin • Several salivary isoenzymes • Maltose is the major end-product (20% is glucose) • Parotis; 30% of total protein in parotid saliva • “Appears” to have digestive function - inactivated in stomach, provides disaccharides for acid-producing bacteria • Why is it also present in tears, serum, bronchial, and male and female urogenital secretions? • A role in modulating bacterial adherence?

16. Lingual Lipase • Secreted by lingual glands and parotis • Involved in first phase of fat digestion • Hydrolyzes medium- to long-chain triglycerides • Important in digestion of milk fat in new-born • Unlike other mammalian lipases, it is highly hydrophobic and readily enters fat globules

17. Statherins • Calcium phosphate salts of dental enamel are soluble under typical conditions of pH and ionic strength • Supersaturation of calcium phosphates maintain enamel integrity • Statherins prevent precipitation or crystallization of supersaturated calcium phosphate in ductal saliva and oral fluid • Produced by acinar cells in salivary glands • Also an effective lubricant

18. Proline-rich Proteins (PRPs) • 40% of AAs is proline • Inhibitors of calcium phosphate crystal growth • Part of pellicula dentis • Subdivided into three groups • Acidic 45% • Basic 30% • Glycosylated 25%

19. Lactoferrin • Iron-binding protein • „Nutritional“ immunity (iron starvation) • Some microorganisms (e.g., E. coli) have adapted to this mechanism by producing enterochelins. • bind iron more effectively than lactoferrin • iron-rich enterochelins are then reabsorbed by bacteria • Lactoferrin, with or without iron, can be degraded by some bacterial proteases.

20. Lysozyme • Present in numerous organs and most body fluids • Also called muramidase • hydrolysis of (1-4) bond between N-acetylmuramic acid and N-acetylglucosamine in the peptidoglycan layer of bacteria. • Gram negative bacteria generally more resistant than gram positive because of outer LPS layer

21. Histatins • A group of small histidine-rich proteins • Potent inhibitors of Candida albicans growth

22. Cystatins • Are inhibitors of cysteine-proteases • Are ubiquitous in many body fluids • Considered to be protective against unwanted proteolysis • bacterial proteases • lysed leukocytes • May play inhibit proteases in periodontal tissues • Also have an effect on calcium phosphate precipitation

23. Salivary peroxidase systems • Sialoperoxidase (SP, salivary peroxidase) • Produced in acinar cells of parotid glands • Also present in submandibular saliva • Readily adsorbed to various surfaces of mouth • enamel, salivary sediment, bacteria, dental plaque • Myeloperoxidase (MP) • From leukocytes entering via gingival crevice • 15-20% of total peroxidase in whole saliva

24. 30 No sleep 20 10 sleep 12 am 6 am 12 pm 6 pm 12 am 6 am 12 pm 6 pm 12 am CIRCAIDIAN RHYTHM OF SALIVA FLOW • Time of day

25. Meal during this period Effect of feeding on salivary secretion 10 min collection periods

26. Variations in salivary composition • Unstimulated flow • Submandibular g. 70% • Parotid g. 20% • Accesory g. 7% • Sublingual 2% • Acid stimulation • Submandibular g. 45% • Parotid g. 45% • Chewing • Submandibular g. 30% • Parotid g. 60%

27. Variations in salivary composition • Parotid secretion increased amylase content • Submandibular secretion increased calcium concentrations

28. Gingival cervicular fluid Seminar Stomatology

29. Gingival cervicular fluid • Synonyms: • Gingival fluid • Cervicular fluid • Sulcular fluid • Similar composition as interstitial fluid • Flow rate related to degree of gingival inflamation, circa 0,5-2,4 ml/day

30. Composition • Cells • Desquamated epithelial cells • Neutrophils • Small amount of lymphocytes and monocytes • Bacteria • Inorganic ions • Similar to plasma • Potassium 2 x higher than in plasma (cell break-up) • Calcium higher than in oral fluid • Organic components • Similar to plasma - serum albumin, globulins, complement, protease inhibitors • Small organic molecules - lactate, urea, hydroxyproline • Enzymes

31. Function • Protective flow towards oral cavity - washes out potentially harmful cells and molecules • Antibacterial - immunoglobulins • Calcium assists pellicle and plaque fromation but may contribute to calculus formation • Rather response to inflamation

32. THANK YOU