Vitamin B is effective for nutritional deficiency mouth ulcers that are deficient in vitamin B. It is not very effective for the majority of mouth ulcers. As one of the most common diseases in dentistry, especially in oral mucosa, the cause of mouth ulcers has not been fully determined, and there are immune factors, low immunity and abnormal immune function. Mouth ulcers are prone to be more frequent. These include genetics, certain nutrient deficiencies, infectious factors, and even psychological and hormonal factors, all of which have been shown to have some relationship with mouth ulcers. Therefore, mouth ulcers caused by multiple causes can hardly be completely cured by supplementing with a single vitamin.