Specifically, periodontal pathogens such as Porphyromonas gingivalis and Fusobacterium nucleatum promote oral cancerization by modulating molecular, genetic, and epigenetic pathways, including p53, Cyclin D1, Ki-67, p16INK4A, DNA methylation, histone modifications, and microRNA regulation. This evidence concerns the gene CCND1 and lip and oral cavity carcinoma.