If a tooth is damaged, swollen or painful, an abscess may have formed under the tooth. Root canal treatment may stop the tooth from being removed by treating the infection quickly. An x-ray is necessary to assess the problem and give advice. The next stage is to clean out the infection. The dentist will use a drill and make a hole in the top of the tooth and remove the pulp. The root canal of the tooth is then cleaned, filled and sealed. A second appointment will be necessary to check the state of the tooth.