The pain in the innermost flesh of the left tooth may be a pericoronal abscess produced by the erupting tooth, and this condition can usually be rinsed locally because in the process of tooth eruption is to break the top of the gum flesh, which slowly recedes to the far side of the tooth before the entire tooth surface is exposed. In this case, you can go to the stomatology department to use hydrogen peroxide and saline for alternate rinsing to rinse out the food residue and pus inside, which can quickly relieve the pain, and if necessary, you can take oral anti-inflammatory drugs, such as cephalosporin, amoxicillin, or you can choose erythromycin and other drugs. It is recommended to use mouthwash, which can effectively inhibit the bacterial infection in the mouth. Usually, you should brush your teeth normally, and if you have symptoms of restricted mouth opening, you should practice mouth opening training after the inflammation subsides. If the pain is caused by the eruption of the wisdom tooth, the wisdom tooth can be removed after the inflammation subsides to avoid recurrence.