Patients with bad breath are mainly caused by two aspects, namely suffering from oral local and other systemic diseases such as digestive tract, as follows: 1. Oral system diseases: the most important is due to long-term poor oral hygiene, no serious brushing, rinsing, and no regular ultrasonic scaling treatment in the hospital, it will lead to suffering from periodontitis or gingivitis. With these two inflammatory conditions, the main clinical symptom is a bad taste in the mouth and very foul breath. If there are other diseases in the mouth, such as multiple teeth in the mouth are suffering from deep and large cavities, dental caries will lead to food embedding and will increase the number of pathogenic factors in the mouth, which will also cause serious bad breath. 2, other systemic diseases: digestive system causes, such as due to improper diet, long-term eating greasy, not easy to digest food, may lead to the accumulation of food and cause bad breath, so that the mouth There is a sour odor in the mouth. In addition, if suffering from Helicobacter pylori infection, gastric dysplasia and other gastrointestinal disorders, there will also be bad breath.