In the process of oral cancer development, there is a period of time when the manifestations are not specific and may be the same as various common oral diseases. Therefore, changes that occur in the oral cavity should not be blindly guessed as “fire”, but should be seen by a dentist in time. If common oral diseases are not diagnosed and treated in time, there will be a lot of delayed diagnosis and treatment of oral cancer. Therefore, some people designate April as “Oral Cancer Awareness Month” every year, calling people to pay attention to the changes that occur in the oral cavity. In addition, it is important to have the habit of regular oral checkups, so that not only can you stay away from common oral diseases, but also can detect life-threatening oral cancer early. The habit of regular oral checkups is the theme of National Dental Day on Sept. 20, 2015. Many early oral cancers are discovered during dental visits. During an oral exam, your doctor will help detect any suspicious changes in the mouth, including precancerous lesions, such as white spots, erythema, and submucosal fibrous degeneration of the oral mucosa. Precancerous lesions are not cancerous per se, but some of them may evolve into cancer. It is asymptomatic or mildly symptomatic, persists for a long time, and is not easily detected. Single and limited precancerous lesions can be considered for surgical excision to eliminate future problems; multiple and/or large precancerous lesions have to be monitored by regular checkups and dealt with early once there are changes. Therefore, one must be aware of oral cancer and see a doctor as early as possible for any changes that occur in the oral cavity, and have regular checkups.