Endodontics is the branch of dentistry concerned with  the form, function, and disease of the dental pulp ( what many casually refer to as the "nerve") inside the tooth/ root, and the supporting structures (like the " socket " that houses the root). Its study and practice include the etiology, diagnosis, prevention, and treatment of diseases and injuries to the pulp and/or surrounding tissues.

Root canal therapy is a procedure where the pulp or "nerve" inside the tooth  is removed, and the remaining canal spaces are cleaned,disinfected, and filled with a "gutta percha" type filling material.  Root canal therapy may be necessary for a number of reasons, some of which include:    

•        decay near or into the nerve
•        excessively broken-down tooth structure
•        a cracked tooth resulting in pain to biting pressure             
•        sensitivity to extreme temperatures (hot/cold)
•        an infected nerve resulting in a dental abscess  

In almost all cases, the need for a root canal arises from inflammation or infection inside the tooth or around the roots.  Sometimes a tooth which needs a root canal will be very sensitive, while in other cases, the tooth may be absolutely pain-free.