The space inside the tooth from the center, known as the pulp chamber ,travelling down the length of the root to the tip or apex is called a canal; more specifically a root canal. Human teeth may have 1 to 4 root canals depending on the anatomy of the tooth. Molars may have 2 to 4 canals, premolars may have 1 to 2 canals, cuspids may have 1 to 2 canals, and finally incisors generally have 1 canal. Extra canals may branch out from the main canal, called accessory canals. The anatomy and morphology of the root canal within each tooth may vary significantly.
The tiny canals contain the pulp of the tooth, also commonly referred to as the nerve, which originates from the pulp chamber. When tooth decay invades the pulp, tooth trauma occurs and results in the exposure of the nerve, or simply a slowly dying tooth due to aging, root canal therapy may be necessary to save the tooth from possible removal.
The term "root canal" is often referred to the dental procedure "root canal therapy" or RCT.
