Barbara Manconi

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1. Introduction Saliva is a multifaceted bodily fluid that contains enzymes (amylases, lysozymes, and lipases), proteins, peptides and glycoproteins, lipids (hormones such as testosterone and progesterone), and proteases, along with a high concentration of inorganic ions [1]. To date, more than 2000 proteins and peptides have been identified in saliva [2]. They are mainly involved in the homeostasis of the oral cavity, the digestion process, and the innate immune response [3].