After brushing teeth or bad breath may only dental disease, periodontal disease or other systemic diseases, specific need to go to the hospital for examination in order to clarify the source of odor. 1. Dental disease. After brushing or bad breath may be caused by dental caries, decayed tooth tissue mixed with food debris embedded in the cavity can emit a foul odor, the need for instruments to remove the carious part of the grinding resin filling. 2. Periodontal disease. Gingivitis, periodontitis, inflammation of the gums can be ulcerated with liquid oozing or even pus overflow, emitting a foul odor. It is necessary to do periodontal treatment to eliminate the inflammation of the gums, and the odor will disappear slowly. 3. Systemic diseases. Digestive diseases such as gastric ulcer, esophagitis or respiratory diseases such as bronchitis, bronchitis, odor will also be emitted through the oral cavity, this time you need to combine with the internal medicine physician for diagnosis and treatment. After brushing your teeth or bad breath, it is recommended to go to the hospital in time to do oral and systemic disease examination to clarify the cause.