Sour mouth odor may be bad oral habits, poor diet and other physiological factors, but also may be periodontitis, gingivitis, pulpitis and other diseases. 1. Physiological factors: usually patients usually do not pay attention to oral hygiene, resulting in bacterial growth, often appear sour mouth odor, and consumption of garlic and other stimulating foods, food residues in the mouth, may also appear bad breath. 2. Periodontitis: It is usually considered to be related to plaque, tartar, traumatic bite, food impaction, heredity, smoking, mental stress and other factors. Patients often have red and swollen gums, bleeding from probing, pus overflow from periodontal pockets, loose teeth and other symptoms, while some patients may also be accompanied by periodontal abscess, very surface caries, bad breath and other phenomena. 3. Gastrointestinal diseases: gastric ulcer, chronic gastritis and other diseases, there will be digestive dysfunction, excessive secretion of gastric acid, etc., and the patient’s mouth may have a sour and rotten taste. In addition to the above factors, it is also considered to be related to vitamin deficiency, dental caries, periodontal abscess and other conditions. Patients are advised to find out the cause of the disease in time and treat it reasonably when the symptoms of sour taste in the mouth appear.