The mouth rotten should be a mouth ulcer, there are many causes of mouth ulcers, probably including the following: 1, eating too fast, the oral wall mucous membrane bite caused by mouth ulcers. 2, the teeth are not aligned, in chewing food often can bite to a location in the mouth, the location is easy to form mouth light ulcers. 3, the mouth has bad material dentures, dentures often stimulated to a location in the mouth, often stimulated to the location of mouth ulcers. 4, often stay up late, irregular diet, fire caused by mouth ulcers. 5, do not like water, do not like to eat fruits and vegetables are more likely to have mouth ulcers. The location that is often stimulated to have mouth ulcers. 4, often stay up late, irregular diet, fire caused by mouth ulcers. 5, people who do not love to drink water, do not love to eat fruits and vegetables are more likely to have mouth ulcers. 6, the body resistance is too poor also easy to ulcers. The mouth ulcer does not need treatment, about 10 days will be self-healing, do not worry too much, usually recommend a light diet, eat more fruits and vegetables.