There are many reasons for ulcers in the mouth probably divided into the following: 1, eating too fast, bite to the oral wall mucosa caused by mouth ulcers. 2, poor quality dentures in the mouth, dentures stimulate the oral mucosa caused by mouth ulcers. 3, teeth are not aligned or wisdom teeth tilt growth, resulting in frequent bites to a location of the oral mucosa, often bitten location is easy to have ulcers. 4, body resistance. Too poor. 5, lack of vitamins caused by the mouth ulcers. Patients with ulcers in the mouth do not need to worry too much, do not need to take treatment about 10 days ulcers will heal themselves, if the ulcers are painful can spray some watermelon cream spray in the affected area, but for oral ulcers caused by good restorations inside the mouth, it is recommended to take out the bad restorations in time to avoid repeated ulcers.