A root canal is not something that we normal humans would look forward to. How about the poor people who have to have a root canal retreated? It’s a common perception that once a root canal has been done, there will never have to be anything else to do for that tooth. While that is true with most root canals, there is an occasional one that is not successful.
The most common reason is not being able to get a good seal on the root. Any leakage around the root canal filling material can allow bacteria to filter in. Since there are no blood vessels in the area (those were removed by the root canal process), there will be no way to get antibodies and white blood cells to the area. This way, the bacteria can proliferate causing an infection. The only way to correct this problem is to retreat the root canal. That is done by opening up the tooth, then softening and removing the gutta percha filling material. After that is done, it’s a good time to search for extra canals or unusual root anatomy. All of the canals are cleaned thoroughly and irrigated with sodium hypochlorite. At this point, a decision is made on whether to place medication in the tooth and allow it to heal for a week or two or to go ahead and fill it that day. Retreatments do not enjoy the same success rate as original root canals, but they work often enough that they are sure worth giving a try.