~Root Canals~
The pulp or pulp chamber is the soft area within the center of the tooth. The
tooth's nerve lies within root canals, which lie within the roots or "legs" of
the tooth. The root canals travel from the tip of the tooth's root into the pulp
chamber, which also contains blood vessels and connective tissue that
nourish the tooth.  When nerve tissue or pulp is damaged, it breaks down
and bacteria begins to multiply within the pulp chamber. The bacteria and
other decayed debris can cause an infection or abscessed tooth. An abscess
is a pus-filled pocket that forms at the end of the roots of the tooth. An
abscess occurs when the infection spreads all the way past the ends
of the roots of the tooth.  

Therefore, a root canal is a treatment used to repair and save a tooth that is
badly decayed or infected. During a root canal procedure, the nerve and pulp
is removed and the inside of the tooth is cleaned and sealed.

A tooth's nerve is not vitally important to a tooth's health and function after the
tooth has emerged through the gums. Its only function is sensory – to provide
the sensation of hot or cold. The presence or absence of a nerve will not affect
the day-to-day functioning of the tooth.

After a root canal is completed, the tooth can become very brittle since the
blood supply is lost to the tooth.  Therefore it is very commonplace to come
back for another appointment to have a crown done on that tooth.    
Advanced Dental Care