This review highlights the mechanistic roles of salivary biomolecules, including microRNAs (miRNAs) (e.g., miR-31, miR-200a), proteins (interleukin-8 (IL-8), matrix metalloproteinase-9 (MMP-9)), circulating tumor DNA (ctDNA), and metabolites, in OSCC pathogenesis. Here, MMP9 is linked to neoplasm.