With proper care, even teeth that have had root canal treatment can last a lifetime. But sometimes, a tooth that has been treated doesn't heal properly and can become painful or diseased months or even years after treatment. If your tooth failed to heal or develops new problems, you have a second chance. An additional procedure may be able to support healing and save your tooth. If you have pain or discomfort in a previously treated tooth, talk to an endodontist about retreatment.