- Tobacco - This is the single biggest culprit in the development of almost all pre-cancerous lesions and is the leading cause of oral cancer as well. Tobacco itself has around 4,000 chemical constituents among which dozens are known carcinogens (cancer causing chemicals). Here again the two main culprits are tar and nicotine. Both of this have a high potential to cause pre-cancerous conditions as well as full-blown cancer.
- Alcohol - Alcohol is a potential culprit in these cases since it is known to irritate the oral mucosa or gums to a certain extent. However, it is not as problematic as tobacco and is rarely the single causative factor.
- Syphilis - This is a sexually transmitted disease that is sometimes implicated in the development of pre-cancerous conditions. There have been reports of high incidences of these lesions in patients with syphilis.
- Sharp tooth - A sharp tooth that causes chronic irritation to a certain area in the mouth time and again is also responsible for the development of a pre-cancerous condition.
- Vitamin deficiency - Although this is not proved beyond doubt certain pre-cancerous conditions occur commonly in patients with Vitamin A and Vitamin B complex deficiencies.