Summary : Root treatment involves the removal of the nerve from the tooth by drilling a hole in the top surface of the tooth. The inside is cleaned out with disinfectants and needle like fine instruments. The root canal is then dried and a rubber filling placed down the inside of the tooth. This is then sealed with a white filling material to prevent any bacteria entering.
The treatment cleans the inside of the tooth and removes any bacteria or dead pulp tissue. The root filling prevents bacteria reinfecting the tooth and causing toothache. Once this has been completed the tooth can have a crown or filling placed on top which will then allow the tooth to function normally.
It is important to preserve teeth as they are irreplacable and further complications can arise later due to the remanent space in the mouth. Typical problems that might occur when a tooth is extracted are;

Teeth opposite the tooth extracted may overerupt down into the space left by the lower tooth.

Teeth adjacent to the lost tooth may tip and rotate making biting uneven.

Bone is lost after tooth extraction, in those with no teeth the bone is lost continually throughout life eventually leaving very little bone for the denture to sit on.

The loss of a front tooth may result in a poor appearance both because of the gap and also because bone is lost causing the face to sink in. Many denture wearers are concerned of this as it makes them appear older. The loss of the tooth may also interfere with speech as many sounds are made by the tongue touching the back of the front teeth.

To learn the basic details of root treatments read this section which outlines what treatment your dentist will do. Once you've understood the basic section you can progress to the advanced level and learn the finer points of root treatment.