One of the most common statements I hear from patients experiencing dental pain related to teeth that have already had root canal therapy is “but I thought there’s no nerve and I won’t ever have a problem?“…
Unfortunately this is far from reality. Typically, a root canal is done when the tooth’s nerve is so badly inflamed that it cannot heal itself. This can happen from a bad cavity, chronic decay underneath an existing filling or crown, or from a tooth fracture. Since the nerve is beyond the point of repair, there is pain or infection, and it must be removed. The space that the nerve used to occupy is filled and sealed with a material called “gutta percha”, aka root canal.
The sealant, however, may not last forever. New decay can form and the bacteria causing the decay can travel the entire length of the root all the way to the tip and into the jawbone. What happens next is cyst formation in the bone as your immune system attempts to cope with the bacterial infiltration. When the cyst reaches a certain size, there is pain when you bite down. Not tooth nerve pain, but jawbone pain!
Sometimes another attempt at root canal can be done to remedy this. It really depends on the circumstances and whether the adjacent teeth are impacted or whether the new decay is beyond repair. Other times the jawbone is so badly infected that the tooth cannot be saved and must be removed. The general industry consensus is that the average lifespan of a root-canaled tooth is about 7 years before it needs attention. That’s only an average, however. I’ve seen root canals fail after 1 week, and I’ve seen decades of success.
Another unfortunate consequence of a root canal is the tooth is generally rendered more brittle and prone to fracture. If there is a post as part of the restoration, that also represents a weakness in the tooth structure. Natural, intact teeth rarely fracture, but when we do see a fractured tooth it’s almost always one with a history of root canal therapy.
It would be nice if clinicians were a little bit more forthcoming about the longevity and realistic expectations of doing a root canal. It’s still one of the best way to preserve an infected tooth. Unfortunately like just about anything else, it’s not without real risks, and there’s a good chance it won’t last forever.