Can a root-canal-treated tooth become painful again?

Yes, it can become painful again. The root canal system is complex, with tiny accessory canals that are not visible to the eye - if bacteria remain in those areas, inflammation can come back over time. If this happens, 1) we first try retreatment by removing the previous filling and re-disinfecting the canals, and 2) if that does not resolve it, we can save the tooth with an apicoectomy, in which the inflamed tip of the root is surgically removed. If a root canal-treated tooth hurts when you chew, or a bump (fistula) appears on the gum, please come in for a check.