IL17A and periodontitis: Considering that during periodontitis, the Th17 lymphocytes producing IL-17 plays a central role as the main activator of osteoclasts and in the breakdown of the BBB, the levels of IL-17 in trigeminal ganglia or hippocampus should be studied in the future (Kebir et al., 2007; Vernal et al., 2014b; Monasterio et al., 2018a; Monasterio et al., 2018b).