Expert: Frederick R. Liewehr DDS, MS, FICD - 6/6/2006

Question
Hello, I had a root canal performed some time ago then my general dentist set a temporary then a permanant crown on that tooth. For many years I had persistant chronic pain and throbing in the tooth and gum area where my root canal was performed along with migraine headaches and other symptoms. Taking it upon myself to seek another dentist to find the source of my pain, he retreated the root canal and was surprised to find cotton pellets and temporary filling still lying underneath the permanant crown.
Do you have any opinion or explanation as to why my pain ceased when the temporary filling along with the cotton pellets were removed and the area irragated. I am so happy to finally be pain free.
Thanks so much for your time.

Answer
Hi Jane,
     I can't give you an explanation for why your former general dentist left the temporary with cotton in your tooth instead of placing a proper base prior to placing your crown. There is absolutely no reason to do that, but unfortunately I have seen it many times myself as well. What can I tell you?
     The enemy we are fighting is bacteria. It is those buggers that cause infections. I would like to tell you that root canal filling, regular fillings, and crowns all seal perfectly and keep them out of your tooth, but that would be a lie. They don't. Even today's "bonded" restorations break down, if the bond is actually good in the first place, usually within a year. It is possible that your general dentist believed that once he placed the crown on the tooth he would seal and cover everything so it would not matter what was inside, but that is not the case. He also may believe that even if the temporary leaked, and they do - quickly, which is why they are called "temporary" - the root canal filling would seal the roots. This is also incorrect - one well-known study showed that as a worst-case scenario, teeth that are root-filled but don't have a restoration can leak completely through the roots to the bone in as little as three days.
    So, my guess is that you had salivary leakage with its resident bacteria into the tooth over time, which set up an infection in your bone and caused the pain. Once they were cleaned out and the root canal disinfected (we probably rarely actually eradicate all the bacteria with our current techniques) you got better and the pain stopped.
    Since all those things leak, we have to use a combined approach: good root canal, good permanent restoration, and good crown. With that kind of care, your treatment should hold up for a long time indeed. Good luck!

Dr. Liewehr