In addition to the above 2 hub DEPs, there is no direct evidence from previous studies for the remaining hub DPEs (TMED5, HLA-DPA1, CD79A, ADPGK, TBXAS1 and PLCH1) correlating closely with periodontitis, OCN had been reported that it is involved in the physiological or pathological process of periodontitis. This evidence concerns the gene HLA-DPA1 and periodontitis.