Saliva secretion composition, function

Saliva production

• From major paired salivary glands: parotid, submandibular, sublingual

• Parotid gland produces serous, watery, amylase-reach saliva

• Submandibular gland, produces mixed fluid from mucous and serous acinar cells, saliva is slimy mucin-rich more viscous than former one

• Sublingual gland produces more viscous fluid mainly from mucous acinar cells

Saliva production

• Minor salivary glands in oral mucosa produce mixed saliva apart from lingual Ebner’s glandswhich are serous, and palatine which are strictly mucous glandsare strictly mucous glands

They are found in many parts of the mucosa

They are named according to their location for ex.:labial, buccal lingual, gloosopalatine glands

Saliva composition and related function

• 99% water• 1% solidsmostly proteins and elektrolytes

• Functions of saliva relate to both its fluid charakteristics and specific components

• Fluid charakteristics: rinsing effect, solubilization of the food taste substances, bolus formation, food and bacteria clearance, dilution of detritus, lubrification, facilitation of mastication, swallowing, speech

• Specific components: protection of tooth structure by neutralization of acids by buffering action, by maintaining supersaturated calcium phosphate concentration, with regard to hydroxyapatite

amount

• Daily production of saliva is 0.5-1 l

• Unstimulated whole saliva flow-rate is 0.1-0.3ml/min

• Stimulated flow is 0.5-1.5ml/min

Xerostomia

• Xerostomia is related sensation of mouth dehydration

• Defined as subjective feeling of a sensation of oral dryness• Defined as subjective feeling of a sensation of oral dryness

• Impairs oral functions and even quality of life

hyposalivation

• Hyposalivation occurs when measured salivary flow rate • Hyposalivation occurs when measured salivary flow rate

• Stimulated is less than 0.5ml/min

• Unstimulated is less than 0.1ml/min

• Is a term based on objective measures of saliva production

• Nearly always results in altered salivary composition

Oral symptoms of hyposalivation and xerostomia

• Mucosal dryness and soreness

• Burning sensation of mucosa and tongue

• Difficulties in speech

• Difficulty in swallowing

• Taste impairment

• Difficulty in wearing removable dentures

• Dry lips, angular cheilitis

• Atypical caries pattern, carious lesions on smooth surfaces

• Increased frequency of oral infections

Causes of hyposalivation

• Medication with side-effect of decline in the secretion rate

• Polypharmacy

• Radiation therapy to the head and neck region

• Autoimmune diseases: Sjorgren’s syndrome, sarcoidosis

• Menopause

• Severe immune deficiencies AIDS

• Depression

• Diabetes mellitus type I

• Salivary gland stones

medications

Antispasmodic, antidepressants, antipsychotic, parkinsonian, Antispasmodic, antidepressants, antipsychotic, parkinsonian, arrhytmia medications, antihistamine, appetite depressants, arrhytmia medications, antihistamine, appetite depressants, anticonvusant, anxiolytic, antihypertensive, diuretic, anticonvusant, anxiolytic, antihypertensive, diuretic, skeletal muscle relaxantsskeletal muscle relaxants

Salivary clearance

• Dilutes• Dilutes

• Eliminates the substances introduced into oral cavity

Oral clearance after sugar consumption

• average residual volume of saliva after swallowing is 0.8ml

• The small amount of sucrose will dissolve in this residual volume of saliva

• this will give rise to a very high sucrose concentration• this will give rise to a very high sucrose concentration

• Taste of sugar with flavoring agents stimulates salivary glands to produce saliva

• The volume of saliva will increase until maximum 1.1ml is reached

• It will induce swallowing [0.3ml] and clearing some of the sucrose

• when concentration of substance decreases the stimulation stops

• It results in slower clearing process

Oral clearence depands on

• Salivary flow rate• Salivary flow rate

• Volumes of saliva before and after swallowing

• Characteristic of substance entering oral cavity

• Place in the oral cavity: better clearing action occurs near the opening of salivary duct

Buffering ability of saliva

• Carbonic acid/bicarbonate system• Carbonic acid/bicarbonate system

• Inorganic orthophosphate

• macromolecules

Hydrogen ion

• Is secreted via the salivary glands• Is secreted via the salivary glands

• Produces by oral bacteria

• Taken into the oral cavity: acid drinks [pH of soft drinks and juices ranges from 2.5 to 4]

Carbonic acid/bicarbonate system

• Most important buffering system• Most important buffering system

• Main buffering system in stimulated saliva

• Reduces the hydrogen ions with forming carbon dioxide which is eliminated with breathing

Inorganic phophate

• In unstimulated saliva its concentration is nearly equal to carbonic • In unstimulated saliva its concentration is nearly equal to carbonic acid/bicarbonite system

• Together they take part in buffer capacity in unstimulated rate

Solubility of enamel

• hydroxyapatites pH 5.5• hydroxyapatites pH 5.5

• Fluoroapatites pH 4.5

Lubrication, protection of oral mucosa

• Mucins which are mucous glycoproteins come from acinar cells

• Have high molecular weight

• Contain more than 40% of carohydrates

• Named MG1, MG2

• Are hydrophilic and entrain much water

Protective and reparative environment for teeth

• calcium ion has protective role toward mineral teeth structure • calcium ion has protective role toward mineral teeth structure

• Statherin proline reach proteins PRPs

• They bind calcium ion

• creating stable supersaturated state of this ion in saliva

• They inhibit spontaineous precipitation in saliva

Antimicrobial action

• Agregation of bacteria by agglutinins MG1,MG2, beta 2 microglobulin, fibronectin, the bacterial aggregats are easly removed from oral cavity by swollowing

• Breakege of bacterial wall, by hydrolyzing enzyme which is the part of lysozyme lysozyme

• Lactoferrin- an ion-binding protein, takes iron [Fe+3]from microorganisms, thus provides antimicrobial action

• Antimetabolic activity against several microorganisms perform salivary peroxidase and myeloperoxidase

• Competitive inhibition of bacterial adhesion to enamel

Mg1,MG2, Statherin, PRPs

Immunoglobulins

• IgG-enhancement of phagocytosis

• IgM- enhancement of phagocytosis

Pellicle

• Saliva is separated from tooth surface by thin layer of biofilm called aquired pellicle

• Is defines as acellular layer of adsorbed salivary proteins and other macromolecules on the dental enamel surface

• Approximately 10 micromiters thick• Approximately 10 micromiters thick

• Protects the enamel against abrasion and attrition, also serves as diffusion barrier

• Forms the base for subsequent adhesion of microorganisms

• Is then termed dental plaque

Pellicle – functions:

• Adsorption of the proteins mainly originated from saliva is selective

• certain macromolecules show higher affinity for the mineral structure

• The enamel surface is charged negatively in normal pH, thanks to strucutre of hydroxyapatites

• Ions of opposite charge e.g.calcium, sodium, pottasium, chloride are attracted to the surface, forming a hydration layer,

• The charge of enamel with its hydration layer is positive

• Will attract negatively charged macromolecules

• Selective attachment of bacteria to the enamel surface is achieved when the surface characteristic (adhesins) of bacterium fit with component in the pellicle (receptors)