Unravelling the Potential of Salivary Volatile Metabolites in Oral Diseases. A Review

Abstract

<jats:p>Fostered by the advances in the instrumental and analytical fields, in recent years the analysis of volatile organic compounds (VOCs) has emerged as a new frontier in medical diagnostics. VOCs analysis is a non-invasive, rapid and inexpensive strategy with promising potential in clinical diagnostic procedures. Since cellular metabolism is altered by diseases, the resulting metabolic effects on VOCs may serve as biomarkers for any given pathophysiologic condition. Human VOCs are released from biomatrices such as saliva, urine, skin emanations and exhaled breath and are derived from many metabolic pathways. In this review, the potential of VOCs present in saliva will be explored as a monitoring tool for several oral diseases, including gingivitis and periodontal disease, dental caries, and oral cancer. Moreover, the analytical state-of-the-art for salivary volatomics, e.g., the most common extraction techniques along with the current challenges and future perspectives will be addressed unequivocally.</jats:p>

Emerging Biosensors for Oral Cancer Detection and Diagnosis—A Review Unravelling Their Role in Past and Present Advancements in the Field of Early Diagnosis

“…Saliva contains a variety of electrolytes, including K, Mg, Ca, Na, and P as well as biological elements such as proteins, enzymes, immunoglobulins, and nitrogenous products. Lubrification, antimicrobial activity, buffering action, digestion, and tooth protection are the key activities of this biofluid [ 54 , 55 ]. Saliva has piqued the interest of the scientific community, which has resulted in a flurry of new research.…”

“…However, there are a number of downsides to using saliva as a diagnostic fluid, the most significant of which is its low specificity and sensitivity. Due to the lack of a consistent quantity of saliva in people, the concentration of analytes might vary substantially depending on when the sampling/collection method is performed [ 55 ]. However, the lower level of analytes in saliva is no longer a restriction because many new and sensitive methods, such as microfluidics and nanotechnologies, are introduced, which have enhanced sensitivity and assay speed.…”

Malignancies and Biosensors: A Focus on Oral Cancer Detection through Salivary Biomarkers

“…The mechanisms concerning salivary glands secretion, however, are still mostly unknown. The amount of saliva volume in individuals not being of a standardized value, the concentration of analytes can change greatly depending on when the sampling/collection procedure is carried out [28].…”

“…Saliva is a highly dynamic biofluid whose composition can vary greatly depending on several confounding factors. Confounding factors are defined as contributions to the composition of saliva coming from the environment or from specific activities (i.e., eating and drinking, smoking, playing sports) carried out by an individual [28]. Other confounding factors relate to low aqueous solubility substances that cannot permeate from the circulatory system into saliva and local enzymatic activities within the oral cavity that can originate secondary byproducts.…”

Oxidation, Glycation, and Carbamylation of Salivary Biomolecules in Healthy Children, Adults, and the Elderly: Can Saliva Be Used in the Assessment of Aging?

“…The compounds enter the oral cavity by passive diffusion, active transport, ultrafiltration, or exudation, making saliva rich in many low and high molecular weight compounds. 26 These include proteins, lipids, hormones, antioxidants, and products of oxidation (eg, protein carbonyls, 4-hydroxynonenal (4-HNE), 8-hydroxy-2’-deoxyguanosine (8-OHdG)), glycation (eg, Nε-(carboxymethyl) lysine (CML), AGE), and carbamylation (eg, carbamyl-lysine (CBL)) of biomolecules. 27–31 Although many compounds can also be produced in the salivary glands, the concentration of several biomarkers in saliva highly correlates with their plasma content.…”