Salivary Secretion And Denture Retention

Explain the role of saliva in denture retention.

Factors in Denture Retention

Factors in Denture Retention Extension of Denture Base:

Stensens duct It is rare for a maxillary denture to cause obstruction to this duct.
Wharton duct Extension of the lingual flange in this region can lead to obstruction in which the patient complains of swelling under the tongue while eating.
Sublingual It is rare for a denture to cause any significant obstruction.

Factors in Denture Retention Amount of Saliva

Excess saliva will affect the impression-making procedure and in turn the final denture.
A dry mouth will affect the retention of the denture and result in soreness of mucosa.
When new dentures are worn for the first time increased salivation is seen in some patients and these patients need to be told that over a period of time, salivary flow will come to normal.

Factors in Denture Retention Consistency

Best to work with a serious type of saliva.
Thick saliva decreases complete denture retention, creates hydrostatic pressure in the area anterior to the posterior palatal seal, and results in a downward dislodging force.
Thick saliva also complicates impression-making by forming voids in the impression surface.
Hence before impression making the palatal surface should be wiped free of saliva and the mucus glands massaged with a piece of gauze to eliminate as much mucus as possible.

Factors in Denture Retention Role of Saliva in Denture Retention

The physical forces in which saliva is involved are:

Salivary Secretion And Denture Retention Factors in Denture Retention Role of Saliva in Denture Retention (1)

Factors in Denture Retention Adhesion

Adhesion is the physical attraction of, unlike molecules to each other.
It acts when saliva sticks and wets the basal surface of the dentures and at the same time to the mucous membrane. Watery saliva is quite effective, provided the denture base material can be wetted.
Saliva that is thick and ropy adheres well to both the denture base and the mucosa, but the hydraulic pressure produced by the thick mucus secretion overpowers the adhesive forces of the denture and dislodges the denture.

Factors in Denture Retention Cohesion

Cohesion is the retentive force that occurs in the layer of saliva between the denture base and the mucosa. To be effective the saliva should form a thin layer.

Factors in Denture Retention Interfacial surface tension

Interfacial surface tension is the resistance to separation possessed by the film of liquid between two well-adapted surfaces. It is found in the thin film of saliva which is similar in its action to cohesion and to capillary attraction.

Factors in Denture Retention Capillary attraction

Capillary attraction is a force that causes the surface of a liquid to become elevated or depressed when it is in contact with a solid.

Factors in Denture Retention Peripheral seal

Developed with the proper extension of the denture into the vestibule.
The denture border merging against the mucosal border assembled by a thin film of saliva provides a border seal as it prevents the ingress of air, thus enabling the denture to be in its position.

Factors in Denture Retention Viscosity of saliva

The force required to displace a denture is proportional to the viscosity of saliva fluid film and the square of the area of the denture and inversely proportional to the square of the distance separating the denture from the supporting tissues and the time of force application.
The degree of retention possessed by the denture depends on the area of its fitting surface degree of closeness of fit and viscosity of the saliva.
The glycoproteins and the proteoglycans dissolved in the saliva increase the viscosity and provide it with pseudo-plastic properties.
When mastication is not taking place, saliva acts as a semisolid. In the mouth the dentures are not immersed all the time, hence a meniscus can form at the periphery and surface tension can be included as a factor.

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