Halitosis is divided into endogenous halitosis and exogenous halitosis, daily brushing or halitosis may be caused by dental or periodontal disease, may also be caused by digestive or respiratory diseases. 1. Exogenous bad breath. Daily brushing or bad breath may be teeth caries, decayed material in the cavity caused by bad breath, the need for special instruments to remove the decayed material after resin filling, may also be a periodontal abscess local oozing pus triggered by bad breath, the need for supragingival scaling to eliminate gingival inflammation. 2. Endogenous bad breath. Halitosis may be from the body’s internal odor, can be seen in gastric ulcer, gastritis or bronchitis and other digestive and respiratory diseases, need to be combined with the internal medicine physician to treat systemic diseases. If bad breath has seriously affected the work and life, it is recommended to go to the hospital as soon as possible to check the cause of the disease and timely treatment.