Herein, we hypothesized that E‐cadherin and p16ink4a hypermethylations may cause the aberrant expression of these proteins, based on which, we examined DNA methylations in the promoter regions of E‐cadherin and p16ink4a in OLP, and compared them with those in non‐inflamed healthy gingiva (Non), radicular cyst (RC), and oral squamous cell carcinoma (SCC). This evidence concerns the gene CDH1 and oral cavity squamous cell carcinoma.