oralfluid

Oral fluid is a collective term for the liquids found in the oral cavity, primarily saliva, but also including gingival crevicular fluid and other mucosal transudates. It is produced by major and minor salivary glands and by cells of the oral mucosa. The major glands include the parotid, submandibular, and sublingual glands, with minor glands contributing as well. The composition of oral fluid is complex and dynamic, consisting mostly of water and a mixture of electrolytes (such as calcium, bicarbonate, phosphate, sodium, and potassium), organic molecules (proteins, enzymes like amylase and lingual lipase), mucins, immunoglobulins (notably secretory IgA), antimicrobial peptides, and desquamated epithelial cells. Gingival crevicular fluid adds serum-derived components and inflammatory mediators, and its concentration can increase with periodontal inflammation.

Functions include lubrication and protection of the oral mucosa, initiation of digestion, buffering to neutralize acids, remineralization of teeth through calcium and phosphate, and antimicrobial defense through various proteins and enzymes.

Collection and handling: oral fluid can be collected as unstimulated or stimulated saliva. Stimulated saliva often yields higher volume but differs in composition from unstimulated saliva. Processing should minimize proteolysis, and samples are typically stored frozen or refrigerated; pH and osmolality can impact downstream analyses.

Applications: as a noninvasive diagnostic medium, oral fluid can be analyzed for hormones, drugs and metabolites, infectious agents, genetic material, and biomarkers of systemic or oral health conditions. In research and clinical settings, it supports monitoring of diseases such as Sjögren's syndrome, assessment of dental caries risk, and surveillance for pathogens. Variability due to circadian rhythms, hydration, stimulation, medications, and health status can affect results, underscoring the need for standardized collection and analysis.