ROLE OF SALIVA

BY : EKTHA PAI

SALIVA Saliva is a clear, tasteless, odorless, slightly acidic

viscid fluid, consisting of the secretions from the major and minor salivary glands of the oral cavity.

The teeth are in constant contact with ,and bathed with saliva and hence it profoundly influences the dental caries process.

It is a major modifying factor of the process as it is the medium in which dental plaque develops and works.

The elementary composition of saliva and its approximate percentage under various circumstances , is correlated with incidence of dental caries.

THE SALIVA FACTORThe properties of saliva

which contribute towards protection of the teeth against caries process are:

1. Composition2. pH3. Buffering capacity4. Quantity5. Viscosity6. Antibacterial

factors

COMPOSITION Many inorganic and organic components

of saliva have been investigated for anticariogenic effects.

In normal circumstances, saliva is supersaturated with calcium and phosphate ions with respect to enamel hydroxyapatite.

This not only prevents enamel from dissolving but even tends to precipitate apatite in the surface enamel of carious lesions.

PH OF SALIVA The “critical” pH at which

the inorganic material of tooth begins to dissolve is about 5.5 since above this pH saliva is supersaturated with Ca and PO4 ions.

Acid production during caries occurs at a localized site on the tooth, which in the initial stages at least, is covered by dental plaque. This plaque prevents the free exchange of ions.

BUFFERING CAPACITY The chief buffer

systems are bicarbonate carbonic acid (HCO3

-/H2CO3) and phosphate(H2PO4

- / HPO4

-) The bicarbonate in

saliva is able to diffuse into the dental plaque to neutralize the acid formed from carbohydrate by the microorganisms.

ACIDIC pH

BREAKDOWN OF SALIVARY

BICARBONATES

REMOVAL OF CO2

RISE IN pH

QUANTITY OF SALIVA Caries incidence is significantly higher in

people with less or no saliva flow, as is seen in cases of salivary gland aplasia and xerostomia.

Continuous flow of saliva is required for mechanical removal of bacteria and food debris from the tooth surfaces.

VISCOSITY OF SALIVA

Viscous saliva is associated with high caries incidence.

Thin watery saliva has also shown caries incidence.

Hence the viscosity of the saliva must be a balance between serous and mucous secretions of the salivary glands.

ANTIBACTERIAL PROPERTIES

Saliva contains many antibacterial factors like lysozyme, lactoferrin, sialoperoxidase, bistatin, thiocyanate ion, IgA, ETC.

Saliva appears to contain bacteria capable of causing caries if carbohydrats are present.

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