If pulpitis is not treated and controlled, the infection can become severe, leading to swollen gums and causing severe pain. During this period, periapical periodontitis can develop. The emergency treatment for acute periapical periodontitis should involve opening the pulp chamber under local anesthesia for drainage, and using the root canal to drain in order to alleviate the pressure at the root apex and relieve pain. Generally, care must be taken to avoid the swollen areas during local anesthesia, as it may cause intense pain and spread of the infection. Hydrogen peroxide can be used for local irrigation.