Ferlazzo N [20]et al. conducted methylation studies by extracting genomic DNA from saliva samples from patients with oral squamous cell carcinoma (OSCC) and healthy controls, and found that p16 and O6-methylguanine-DNA methyltransferase (MGMT) gene promoters in the patient group The methylation frequencies of the methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms were significantly associated with their methylation. This evidence concerns the gene MGMT and oral cavity squamous cell carcinoma.