SALIVA
Seminar
Stomatology
MAJOR FUNCTIONS OF SALIVA









Solvent
Buffering
Lubrication
Remineralization
Digestion
Anti-bacterial
Anti-fungal
Temperature regulation
Production of growth factors and other regulatory
peptides
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
THE SECRETORY UNIT
The basic building block of all salivary glands

ACINI - water and
ions derived from
plasma

Saliva formed in acini
flows down DUCTS to
empty into the oral cavity.
TWO STAGE HYPOTHESIS
OF SALIVA FORMATION
Most proteins
Water &
electrolytes
Na+ Cl- resorbed
Some proteins
Isotonic
primary saliva
electrolytes
K+ secreted
Hypotonic
final saliva
into mouth
Inorganic
components
Saliva compositon
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
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

Other ions

Fluoride
 Low

concentration, similar to plasma
Thiocyanate
(oxidated to hypothiocyanite OSCN- by
active oxygen produced from bacterial peroxides by
lactoperoxidase)
 Higher conc. => lower incidence of caries
 Smokers - increased conc.
 Antibacterial


Sodium, potassium, chloride
Lead, cadmium, copper
 May
reflect systemic concentrations - diagnostics
FLOW RATE ml/min
Concentration (mM)
Organic
components
Saliva composition
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
Multifunctionality
Amylases, Cystatins,
Carbonic anhydrases,
Histatins, Mucins,
Histatins
AntiPeroxidases
Buffering
Bacterial
Amylases,
Cystatins,
Mucins, Lipase
AntiMucins
Digestion
Viral
Salivary
Functions MineralAntiization
Fungal
Cystatins,
Histatins
Histatins, ProlineLubricatTissue ion &Viscorich proteins,
Coating elasticity
Statherins
Amylases,
Cystatins, Mucins,
Mucins, Statherins
Proline-rich proteins, Statherins
adapted from M.J. Levine, 1993
Mucins
Lubrication
 Glycoproteins - protein core with many
oligosaccharide side chains attached by Oglycosidic 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)

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?
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

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

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%
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.
Lysozyme
Present in numerous organs and most
body fluids
 Also called muramidase
 hydrolysis of (1-4) bond between Nacetylmuramic acid and Nacetylglucosamine in the peptidoglycan
layer of bacteria.

 Gram
negative bacteria generally more
resistant than gram positive because of outer
LPS layer
Histatins
A group of small histidine-rich proteins
 Potent inhibitors of Candida albicans
growth

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
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
CIRCAIDIAN RHYTHM OF SALIVA FLOW
30
No sleep
20
10
sleep

12 am
6 am
12 pm
6 pm
12 am
6 am
Time of day
12 pm
6 pm
12 am
24
Effect of feeding on salivary secretion
Volume of saliva collectecd each 10 min
0,035
Meal
during
this
period
0,03
0,025
0,02
0,015
0,01
0,005
0
10 min collection periods
25
Variations in salivary composition

Unstimulated flow
 Submandibular
g. 70%
 Parotid
g. 20%
 Accesory g. 7%
 Sublingual 2%

Acid stimulation
 Submandibular
 Parotid

g. 45%
g. 45%
Chewing
 Submandibular
 Parotid
g. 60%
g. 30%
Variations in salivary composition
Parotid secretion increased amylase
content
 Submandibular secretion increased
calcium concentrations

Gingival cervicular
fluid
Seminar
Stomatology
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

Composition

Cells





Inorganic ions




Desquamated epithelial cells
Neutrophils
Small amount of lymphocytes and monocytes
Bacteria
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
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

THANK YOU