Better known as root canal. It is the removal of the pulp-chemical treatment and mechanic of the inner part of the tooth and filling this space by a shutter.

Spontaneous pain and throbbing, when the use of pain killers no longer resolves. -Very deep Caries. -Tooth that will receive Crown/prosthesis, among others.

Don't. Anesthesia prevents the patient feels pain. In some cases there may be little sensitivity until 72 hours after the treatment, which is resolved by ingesting painkillers.

When there is imperfection existing treatment which can cause lesions or abscesses in the root tip (detected radiographically)

Don't. What happens is the loss of brightness, and can look a yellowish tone. The exaggerated darkening occurs when the tooth has suffered a hemorrhage or mummification before treatment.

There may be severe pain, inflammation, swelling, and even tooth loss.

You can use conscious sedation using nitrous oxide, which helps to combat the anxiety during the course of treatment in addition to be analgesic, lessening any pain you can feel during treatment.