Saliva: a fluid of study for OMICS.

Saliva is a fluid that can be collected easily and noninvasively. Its functions in the oral cavity are well known. Advances in molecular biology and technology, as well as research conducted by the various disciplines of omics (genomics, transcriptomics, proteomics, metabolomics, and metagenomics) have contributed to the identification and characterization of salivary components, including DNA, RNA, proteins, metabolites, and microorganisms. These biomolecules enter the saliva through extracellular and intracellular routes, providing information from several organs and systems and raising the possibility of their use as disease biomarkers. In recent years, these factors have expanded the potential use of saliva as a diagnostic fluid for oral and systemic diseases. This review integrates information regarding salivary biomolecules studied through omics and explores their utility as biomarkers for the diagnosis of several infectious and noninfectious diseases, and the opportunity they represent for the development of point of care devices for clinical application. We also discuss the advantages, disadvantages, and challenges to be overcome in order to establish saliva as a useful fluid for the accurate diagnosis and monitoring of a wide range of diseases.