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This is the branch of dentistry that deals specifically with the pulp within a tooth and the tissues that surround the root of a tooth. The structure of a tooth comprises the external enamel, the inner dentin and the pulp at the core of the tooth.
The pulp extends from the upper pulpal chamber in the crown of the tooth down the root canal towards the apex at the end of the root.
It provides nerves and nutrients to the tooth. A root may have between one and four canals and these canals can have very varied anatomy.
Molar teeth will tend to have a greater number of canals.
The pulp may become infected for many reasons but it is usually as a result of trauma to the tooth or bacteria entering the chamber through neglected dental decay. It may also become infected as a consequence of periodontal disease where bacteria from infected gums penetrates the accessory canals at the surface of the root. Once the pulp becomes injured or diseased it will die.
If the pulp is not removed, the tooth will become infected and severe toothache may develop. Root canal therapy involves opening a tooth to gain access to the diseased pulp, removing the pulp from each canal, cleaning the canal and filling it.
A root-filled tooth may become more brittle and it is normally advisable to have the tooth restored with a crown to protect it. Symptoms of an infected tooth are pain when biting on the tooth and increased sensitivity to hot and cold.
Blackening of a tooth would also indicate that the pulp has died. Often the need for root canal therapy is indicated by full-blown toothache but there may be no symptoms and a dental exam and x-ray is required to diagnose the damage to the pulp. When a tooth becomes non-vital and discolours (usually frontal teeth) as a result then the shade may be restored by bleaching from within the tooth (non-vital bleaching).
In those circumstances where root canal therapy has failed the options for treatment are:
(i) Re-treatment which involves removal of the root filling material and re-doing the process,
(ii) Apicoectomy where the tip of the root is surgically removed and covered by a filling, or,
(iii) Extraction of the tooth.
Depending on the circumstances a root canal therapy may completed in one visit taking much more than an hour. However, a few visits may be required depending on the amount of infection, anatomy of the canals and the sensitivity of the tooth. In the absence of toothache, root canal therapy is not normally painful but the root-filled tooth may be tender for a number of days after the procedure