Sialometry is a measure of saliva flow and is used to diagnose systemic illnesses, to monitor oral mucosal status and general heath and to assess side-effects of medications and chronic diseases. Saliva is responsible for the digestive process, mediates taste sensation, helps maintaining the integrity of dental and mucosal tissues, has antimicrobial action, and contributes to mastication and deglutition.
Saliva is mainly produced by three pairs of major salivary glands (parotid, submandibular and sublingual) and is the principal fluid component of the external environment of the taste receptor cells and, as such plays a role in taste sensitivity. Its main role includes transport of taste substances to and protection of the taste receptor. In the initial process of taste perception, saliva acts as a solvent for taste substances; salivary water dissolves taste substances, and the latter diffuse to the taste receptor sites. During this process, salivary constituents chemically interact with taste substances and stimulate the taste receptor, resulting in an alteration of taste sensitivity. The saliva protects the taste receptor from damage brought about by dryness and bacterial infection, and from disuse atrophy via a decrease in transport of taste stimuli to the receptor sites. This is a long-term effect of saliva that may be related to taste disorders. These various effects of saliva on the taste perception differ depending on the anatomical relationship between the taste buds and oral openings of the ducts of the salivary glands. Many taste buds are localized in the trenches of the foliate and circumvallate papillae, where the lingual minor salivary glands (von Ebner’s glands) secrete saliva. Taste buds situated at the surface of the anterior part of the tongue and soft palate are bathed with the mixed saliva secreted mainly by the three major salivary glands.
The volumes of saliva vary depending on the type and intensity of stimulation. A good salivary flow protects against dental caries, erosion, abrasion and candidiasis. Patients with decreased salivary secretion may present with various medical problems, such as, for example, xerostomia, dry mouth, mucosal inflammation, burning mouth, taste disturbances, tooth tissue demineralization, difficulties with mastication and deglutition and insufficient denture retention.
The parotid glands, one of the three salivary glands, produce saliva with stimulation, such as eating, sucking on a lemon candy, chewing gum, or smelling a tasty meal. The submandibular glands produce saliva on a continuous basis and thus serve to keep your mouth moist even when you are not eating. The total amount of saliva in your mouth is a mixture of fluids generated from saliva glands but also from the crevices of your teeth.
The following tests are implemented in measuring saliva production:
1. Whole unstimulated saliva production. The patient will be asked to sit quietly, without talking or chewing, and spit any saliva that accumulates in the floor of your mouth into a pre-weighed tube. This test is generally done for a total of 5-15 minutes.
2. Stimulated whole saliva production. The patient will be asked to chew on a piece of paraffin or pre-weighed gauze for a period of 5-15 minutes, following which the accumulated saliva is measured, either by spitting into a pre-weighed tube or weighing the wet gauze pad.
3. Stimulated parotid saliva production. Special suction cups are placed over the two small openings in the patients mouth from which the saliva produced by the parotid glands is released. Saliva produced by the parotid glands is collected in pre-weighed tubes for a period of 5-15 minutes. A sour liquid (such as lemon juice) is applied to the tongue throughout the test to stimulate parotid saliva flow.
The amount of saliva flow varies considerably from individual to individual and correlates with the sensation of a dry mouth. Abnormally low amounts of saliva production have been defined for each of the tests described above and indicate that a patient might have disease (such as Sjogrenâ€™s syndrome) affecting saliva production.