Certainly, we observed that peptides and proteins involved in the innate immunoprotection, both specific of the oral cavity and also expressed in other body districts, were abundant in salivary samples of AD patients, particularly proteins acting as ROS/RNS scavengers and with a neuroprotective role, such as S100A8, S100A9, and cystatin B; proteins with antimicrobial activity, such as α-defensins, cystatins A and B, histatin-1, statherin, and Tβ4; and peptides involved in the homeostasis of the oral cavity. Here, S100A9 is linked to Alzheimer disease.