Till now, there are only two meta-analyses published on the COX2 -765G/C and periodontitis [22, 23], one [22] paper showed that -765G/C variants could reduce the CP risk in the co-dominant models (GC vs. GG: ORs =0.77, 95% CI = 0.61–0.94) for Asian, while another [23] paper showed a reduced risk for CP among Chinese population with limited population. Here, PTGS2 is linked to periodontitis.