You can brush your teeth when you have a toothache, and you need to maintain oral hygiene. If the toothache is caused by tooth decay, the tooth will be painful if it comes into contact with hot or cold stimulus, and it may also produce spontaneous pain, so you should visit the hospital immediately for endodontic treatment, that is, root canal treatment. If the tooth is close to the pulp or has invaded the pulp chamber, it may lead to pulpitis and pain. In this case, you should visit the hospital as soon as possible to have the endodontic treatment to remove the bacteria in the root canal and the decayed and necrotic inflammatory pulp, and to use the special dental root canal filling material to fill the root canal, which will remove the inflammation and isolate the external stimulation to prevent the toothache from recurring.