Root Canal Treatment is performed when there is irreversible inflammation of a pulp and bacterial contamination of a nerve tissue in so called pulp inside the tooth.
When bacteria enters the pulp chamber it is usually through existing cavity caused by decay. If the decay is large, the nerve tissue is compromised and bacteria can proliferate inside the tooth damaging other tissues and surrounding bone after getting out. The other possible way is through periodontal ligament, around the tooth. In this instance the root tips become infected first an soon after the whole pulp becomes necrotic.
A reasonable antibiotic treatment is allowed to reduce the size of the swelling and infection and reduce the pain patient is experiencing. In addition a pain killer can be used to manage the situation short term until the tooth becomes treated with root canal.
Root canal procedure requires complete removal of a diseased tissue inside the tooth alongside with the bacteria, and filling the space with gutta-percha closing the space and not allowing bacterial activity.
The procedure is time and technique sensitive especially that many teeth have unusual variations in canal numbers and their shape. Some teeth are so complex that the successful endodontic procedure is just not possible.
In fact the longer the root canal takes the more chances for success as the medications placed inside the tooth have extended time to work through the complex canal system.
After root canal procedure is finished a core buildup is placed to completely rebuild the tooth from the inside. After the core buildup is in place a crown is made for the weakened tooth to gain back the strength and shape.