Having cavities is usually associated with bad breath. This is because the main cause of tooth decay is bacterial erosion of the tooth. When food debris enters the decayed tooth, the bacteria break down the food and produce a special flavored gas that causes a bad taste in the mouth, known as halitosis. To completely solve bad breath caused by tooth decay, you must go to a regular hospital for treatment, remove the decay with professional tools, and fill it with a compatible material. After filling, the tooth will not continue to decay, there will not be a large amount of food impaction, and after the decayed tooth is repaired, there will be no more symptoms of bad breath. In your daily life, you should pay attention to maintaining oral hygiene, brush your teeth and rinse your mouth frequently, and eat less sweet and greasy food. Regular dental scaling and oral checkups at the hospital stomatology department can prevent tooth decay and some oral diseases.