Sometimes there is dead or dying tissue in the canal that holds the roots of the teeth which can cause an abscess, sometimes it is painless but many times it can be a painful experience for the patient. A solution is making an opening into the canal that is in the roots and then removing the diseased tissue from the tooth all the way to the tip of the root and cleaning, shaping, and disinfecting the inside of the canal and then sealing with a plastic material and cement so that bacteria can’t get from the bloodstream back into that space again. In the canal, when it gets infected, the first thing that happens is an increase in blood flow, which causes swelling. The swelling cuts off the blood supply and then the blood can’t fight the bacteria. This causes dead and diseased tissue which becomes a continuous source of food for the bacteria. They grow and then an abscess occurs when the bacteria start getting out to the end of the root and that is when a patient will experience a throbbing pain.
Some symptoms can be sensitivity to hot and cold that lingers afterward, spontaneous throbbing pain, and pain upon chewing. These symptoms do not necessarily mean that the patient needs a root canal. For example, cold sensitivity, if it goes away immediately, may be a sign of an irritated but healthy nerve. However, if you have hot on a tooth and it lingers for a long period of time, most of the time that will be a tooth that needs a root canal.
The most common scenario where it is necessary to do a root canal is because there is infection in the root from decay. Occasionally a root canal is also necessary due to trauma, a cracked tooth, and in rare instances during tooth restoration if the canal is to close to the surface of the tooth.