Percentage methylation of AGTR1 (A), FOXI2 (B), and PENK (C) were obtained using pyrosequencing from 37 oral premalignant lesions (OPLs), including 23 who did not undergo malignant transformation (group A), and 14 who did develop OSCC (group B). (D) Global DNA methylation was measured by the percentage methylation of LINE1 by pyrosequencing and compared in patients from group A and group B. (E) Kaplan-Meier curve in patients with high versus low methylation index (MI) defined by the median of the average percentage methylation of AGTR1, FOXI2, and PENK. (F) Kaplan-Meier curve in patients with high versus low LINE1 percentage methylation by pyrosequencing. Statistical significance was determined by unpaired two-sided Student’s t-test (A-D), log-rank test (E, F).