In the early or active phase of periodontitis, macrophage polarization phenotype as M1 type is mainly induced by Th1 production of IFN-γ and LPS-dominated microbial-associated factors [53], while the proportion of M1 is positively correlated with the progression of periodontal inflammatory activity; in the repair phase of PD, M2-associated factor expression, Th2 and Treg cell immunosuppression and repair effects increased [54, 55]. This evidence concerns the gene IFNG and periodontitis.