Root canal treatment or edodontic treatment is necessary when there is an iflammation or death of the pulp of the tooth (a bundle of nerves and vessels inside the tooth), which is a consequence of deep caries or other extensive injuries. Bacteria appear in the root canals because of the inflammation or death of the pulp. In this environment they reproduce smoothly and inflict even greater damage.
If the granuloma, the chronical inflammation that is the consequence of the pulp inflammation, isn’t treated in time and most of all thoroughly, we can lose the tooth. That is why it is of great importance that we remove the entire inflamed or dead tissue with all the bacteria during treatment, so that the bacteria can’t reproduce. Otherwise the tooth can get inflamed again.