A tooth has two parts. A crown and a root.
The crown is made up of enamel , dentin and pulp in the inside. The root is made of cementum, dentin and pulp. The pulp is the tissue that supplies blood to the tooth and detects pain. Decay may occur in the enamel, and spread to dentin. From the dentin , it may spread to the pulp. From the pulp in the crown, it may go down to the pulp in the root.
Now, the tooth is held to the jaw bones by means of a tissue called the periodontal ligament. The infection from the tooth , when it reaches the periodontal ligament, starts to destroy the bone and causes inflammation of this tissue. When this happens, you start getting pain when you bite on the tooth. This is when most people see a dentist.
Now, your dentist will give you an option of RCT if enough crown is left that can be restored. If the whole of your crown is gone, and only the root remains, you may have to extract the root.
Now let us see what is done in the root canal treatment.
First, the dentist removes all the decayed tissue in your tooth and then goes on till he or she reaches the pulp. Now, he removes the infected pulp. Next he washes the root canal thoroughly with medicament to remove all infected material and bacteria. Next, the root canal will be filled with a soft rubbery material called Gutta Percha. This is done to prevent bacteria from the mouth entering the canal and reaching the the periodontal ligament.
Now that all the infection is removed, the periodontal ligament heals naturally.
Since a tooth is brittle after root canal treatment , it is necessary to wear an artificial crown over that.
And there, you saved your tooth that was infected so badly.. Hope this bit of knowledge helped you! Keep smiling then .. and keep it healthy!!!!