Root canal treatment is a dental procedure that relieves pain caused by an infected or abscessed tooth. During the root canal process, the inflamed pulp is removed. The surfaces inside the tooth are then cleaned and disinfected, and a filling is placed to seal the space.Root canal therapy is necessary when oral bacteria invade the pulp inside of your tooth. This usually happens when a cavity is left untreated for a long time. It can also occur if your tooth becomes cracked or damaged due to trauma.