TNF and periodontitis: Among these, constant bacteremia, provoked by periodontitis or even chewing, can induce low-grade inflammation and the translocation of pro-inflammatory cytokines through the blood-brain barrier [27, 28], which leads to reactive astrocytes producing interleukin (IL)-6 and tumor necrosis factor (TNF)-α, and microglia polarizing towards a neuroinflammatory M1 phenotype [29, 30].