Saliva Composition and Functions: A Comprehensive Review

Abstract

The aim of this study was to perform a literature review about the composition and functions of saliva as well as describe the factors that influence salivary flow (SF) and its biochemical composition. Background: Saliva represents an increasingly useful auxiliary means of diagnosis. Sialometry and sialochemistry are used to diagnose systemic illnesses, monitoring general health, and as an indicator of risk for diseases creating a close relation between oral and systemic health. Review: This review provides fundamental information about the salivary system in terms of normal values for SF and composition and a comprehensive review of the factors that affect this important system. Conclusion: Since several factors can influence salivary secretion and composition, a strictly standardized collection must be made so the above-mentioned exams are able to reflect the real functioning of the salivary glands and serve as efficient means for monitoring health. Clinical Significance: Since many oral and systemic conditions manifest themselves as changes in the flow and composition of saliva the dental practitioner is advised to remain up-to-date with the current literature on the subject.

P2 Receptors as Therapeutic Targets in the Salivary Gland: From Physiology to Dysfunction

“…The importance of saliva, as noted above, is clearly exemplified in individuals suffering from salivary gland hypofunction (Chambers et al, 2004;Atkinson et al, 2005;Meijer et al, 2009). In humans, whole unstimulated saliva is formed from the combined secretions of three pairs of major salivary glands, the submandibular (∼65%), parotid (∼20%) and sublingual (∼7%), along with numerous minor glands spread throughout the oral cavity that produce the remainder of saliva (<10%) (Humphrey and Williamson, 2001;de Almeida Pdel et al, 2008;Proctor, 2016). Upon stimulation, the parotid glands contribute the majority of total salivary secretions (Humphrey and Williamson, 2001;de Almeida Pdel et al, 2008;Proctor, 2016).…”

“…In humans, whole unstimulated saliva is formed from the combined secretions of three pairs of major salivary glands, the submandibular (∼65%), parotid (∼20%) and sublingual (∼7%), along with numerous minor glands spread throughout the oral cavity that produce the remainder of saliva (<10%) (Humphrey and Williamson, 2001;de Almeida Pdel et al, 2008;Proctor, 2016). Upon stimulation, the parotid glands contribute the majority of total salivary secretions (Humphrey and Williamson, 2001;de Almeida Pdel et al, 2008;Proctor, 2016). Three basic cell types comprise the salivary glands: acinar epithelial cells that secrete the majority of the water and electrolytes in saliva, ductal cells that modify the electrolyte concentrations in the primary fluid and myoepithelial cells that provide contractile support for acinar cells (Martinez, 1987;Melvin et al, 2005;de Almeida Pdel et al, 2008;Proctor, 2016).…”

“…Upon stimulation, the parotid glands contribute the majority of total salivary secretions (Humphrey and Williamson, 2001;de Almeida Pdel et al, 2008;Proctor, 2016). Three basic cell types comprise the salivary glands: acinar epithelial cells that secrete the majority of the water and electrolytes in saliva, ductal cells that modify the electrolyte concentrations in the primary fluid and myoepithelial cells that provide contractile support for acinar cells (Martinez, 1987;Melvin et al, 2005;de Almeida Pdel et al, 2008;Proctor, 2016). Salivary acinar cells are either serous or mucous, whereas ductal cells are classified as intercalated, striated or excretory and the distribution of these cell types is dependent on species and type of gland (Melvin et al, 2005;de Almeida Pdel et al, 2008;Proctor, 2016).…”

“…Three basic cell types comprise the salivary glands: acinar epithelial cells that secrete the majority of the water and electrolytes in saliva, ductal cells that modify the electrolyte concentrations in the primary fluid and myoepithelial cells that provide contractile support for acinar cells (Martinez, 1987;Melvin et al, 2005;de Almeida Pdel et al, 2008;Proctor, 2016). Salivary acinar cells are either serous or mucous, whereas ductal cells are classified as intercalated, striated or excretory and the distribution of these cell types is dependent on species and type of gland (Melvin et al, 2005;de Almeida Pdel et al, 2008;Proctor, 2016). Along with the formation and modification of saliva, acinar and ductal cells also secrete important proteins, e.g., amylase and mucins from acinar cells (Boehlke et al, 2015;Frenkel and Ribbeck, 2015), kallikrein from ductal cells (Wong et al, 1983) and growth factors from both cell types (Masahiko et al, 2008), that are integral in maintaining the health of the oral cavity (Proctor, 2016).…”

Saliva is a non‐negligible factor in the spread of COVID‐19

“…Human saliva is abundant of biologically active components, such as proline-rich proteins, mucins MG1 and MG2, and gp340. These components interact with pathogens and cause multiple influences on their biological behavior (de Almeida Pdel, Gregio, Machado, de Lima, & Azevedo, 2008). Moreover, pathogenic viruses in saliva have altered biological patterns such as increased aggregation and communicability (Anschau & Sanjuan, 2020).…”