Studies have shown that following the proper procedures as laid down by the experts (British Endodontic Society or American Endodontic Society) there is on average 70-75% chance of success with root canal treatments over 4-5 years. Following the correct procedures for the root canal treatment, the type of materials used, the type of equipment used and the skill of the treatment provider contribute enormously to the success rate.
The success rate in repeat root canal treatments can be slightly less because a well-developed infection can already be present within the tooth and the anatomical structures around the root in the jaw bone. The success rate of a repeat root canal treatment is still around 70% or more.