Cavities can cause bad breath, because cavities often mean that the teeth appear to be corroded, there is a large number of bacterial reproduction in the area of the cavity, and the food eaten is easy to stagnate in which the fermentation, if not cleaned up in time, the cavity will gradually deepen, become larger, and even appear pulpitis. If not dealt with in time during the pulpitis stage, pulp necrosis will occur, and a more pronounced odor will appear in the mouth. Once a cavity is discovered, it is important to have it filled in a dentist’s office. After the doctor uses a dental drill to clean out the decayed material on the surface of the tooth, and then fills it with resin material, the odor in the mouth will disappear completely. Bad breath can also be caused by periodontitis, gastritis or lung disease, the patient must also be judged.