In a mouse model of apical periodontitis with root canals exposed in the oral cavity and an inflammatory environment established at the osteoclast and osteoblast levels, the expression of PI3K, Acp5, and NFATc1 genes in the chronic apical periodontitis group was significantly increased (p < 0.05) compared with that in the healthy apical tissue group [144]. The gene discussed is NFATC1; the disease is periodontitis.