People need root canals for various reasons, one can be trauma, so if the patient has knocked their tooth, sometimes the nerve does die because the blood supply to the tooth has been cut off. So that indicates a root canal. Otherwise the tooth can die over a period of time.
So even if the patient had trauma when they were quite young, they can be, in their 40’s, 50’s by the time anything comes of it in terms of symptoms. Otherwise the other cause for requiring a root canal can be what we call irreversible pulpitis, which is irreversible inflammation of the nerve. So the only way to treat that is to remove the nerve itself through the root canal process.
Irreversible pulpitis is often as a result of disease such as decay, or the restoration of a tooth.