IL1A and periodontitis: Apart from their important roles in periodontal repair/regeneration [13,14,39,40], AA and retinol exert anti-oxidative effects against periodontitis-induced tissue damages [41,42], demonstrate immunomodulatory capabilities on stem/progenitor cells, dendritic cells, macrophages, T- and B-cells, and markedly downregulate IL-1α, IL-1β, IL-6, TNF-β, and nitric oxide release [43,44,45,46].