Could you explain what is endodontic treatment required for?

Infection removal. Th endodontic treatment is needed when the pulp of the tooth becomes inflamed or infected. In the majority of cases, your tooth can be saved with endodontic treatment.
Nerve removal. Endodontic treatment is required when the nerve in the tooth has become non-vital or irreversibly inflamed. A dead nerve releases toxins into the bone causing an abscess, and a severely inflamed nerve causes unbearable pain. Either way, root canal therapy is indicated to save the tooth.
Infection Control. Endodontic treatment is the process of removing an existing infection from a space within the tooth called the canal. Various instruments and medications are used to clean and shape this area. Once accomplished the space (a pathway from the mouth to the jaw bone) needs to be blocked to prevent reinfection. An inert material is place to seal this pathway followed by a new filling to seal the tooth.
Tooth Infection. It is performed to treat an inflamed or infected pulp. It is also performed as a procedure to allow restoration of a broken or fractured tooth. The ultimate goal is to prevent inflammation of the supporting tissues of the tooth (periapical ligament and bone). .