When tooth infections are neglected they can spread to the nearby tissues.  If allowed to continue, the facial space associated with the tooth can swell.  If left completely unchecked, these facial swellings can spread to and impinge local structures such as nerves.  This can lead to, in rare situations, life threatening emergencies requiring hospitalization.   Before this point is reached, relieving the pressure caused by the infection can help someone avoid these dire circumstances.  This is done by administering local anesthetic and creating an opening from which the infection can drain.  Ususally, this treatment is followed by a course of antibiotics and root canal treatment or extraction of the offending tooth.