The best way to have a rotten tooth that causes bad breath is to have the rotten tooth restored with a filling. The rotten part of the tooth needs to be removed, cleaned up, and then the tooth is filled with a special material. For adults, a resin material is commonly used to fill the tooth, and it is very convenient because it does not interfere with eating after the filling. After the filling, the cavity cannot be filled with food, so it will not cause fermentation of food residue, and the symptoms of bad breath will be significantly relieved. If the decayed tooth is very serious, root canal treatment may be needed, which is commonly known as nerve killing. After killing the nerve, porcelain crowns can be placed to repair the teeth, which not only plays an aesthetic role, but also restores the chewing ability of the teeth. Rotten teeth prove that oral hygiene is not very good, after treatment, we should pay special attention to oral hygiene, to develop good hygiene habits, to avoid new teeth caries caused by bad breath.