The main directions that are supported by current research are listed as follows: (1) systemic inflammation and neuroinflammation: local chronic inflammation caused by periodontitis may activate pro‐inflammatory cytokines like TNF‐α, CRP, and IL‐6, eventually leading to systemic inflammation (Wang et al. 2019; Said‐Sadier et al. 2023). This evidence concerns the gene TNF and periodontitis.