Electronic Cigarettes’ Toxicity: From Periodontal Disease to Oral Cancer

Electronic nicotine delivery systems first appeared on the market in 2003 and have been promoted as healthier alternatives to conventional tobacco cigarettes. The rapid evolution of technology for these products generated a wide variety of models, and electronic cigarettes have quickly gained worldwide popularity. However, research regarding the effects of both short-term and long-term exposure revealed a wide variety of potential negative effects on human health, and the first system to be affected by these electronic smoking devices is the oral cavity. This review makes an up-to-date extensive presentation of the possible mechanisms that associate electronic cigarette smoking with increased prevalence and progression of oral cancer. Oxidative stress, inflammation response, and DNA damage are the main mechanisms that explain e-cigarettes’ cytotoxicity, but there are still questions to be answered. At present, tens of thousands of e-liquids are available, with distinct compositions, which makes the research even more challenging. Another aspect approached in the present paper is the effect of nicotine on chemotherapy drug resistance. Nicotine activates nicotinic acetylcholine receptors, consecutively inhibiting apoptosis, increasing tumor cells proliferation and survival, and reducing the effects of chemotherapy drugs.