No significant differences were observed in the expressions of PAD2 (mean score 1.80 ± 0.60 for periodontitis and 1.74 ± 0.50 for healthy controls) or PAD4 (mean score 2.49 ± 0.60 for periodontitis and 2.42 ± 0.55 for healthy controls) in the epithelium compartment between these two groups (Fig. 4c, d). This evidence concerns the gene PADI4 and periodontitis.