My back lower molars root canal was 2 years ago, it was uncomfortable for days after doing it, crown felt too tight. I believe I was sensitive to heat and cold occasionally and within one month after the root canal would get sensitive on eating on that side, would have to eat on the other side for a couple days and the pain would subside. it has come and gone for this last 2 years. I now have an abscess, it came on suddenly, well maybe was eating too much on this same side but was different, deep and felt like the bone, the dentist took x-rays and feels it needs to be ground to fix a possible uneven bite or the root is cracked. there is a black line on the x-ray inbetween the roots and he says its a bit of bone loss, but just inbetween the roots. he is suggesting that my bite is uneven and this can cause incredible bad things, or its the broken root. I was on ammoxicillan (500 mg x 3 per day) for 48 hours and during this time this painful spot turned into a half golf ball sized lump. perhaps the decay was inside the root where antibiotics do not reach it:?! .. now additionally on metrozidole since 20 hours. this morning the pain has stopped and I think it has stopped to grow. I am not sure what to do, extract this or perhaps try and fix it, if there are still live roots ., I am missing my molar and the next tooth on my other lower side so its a little bit of a big deal to remove this molar as well as I will have few teeth to eat with. any advice, suggestions? I have been reading about how bad root canals are etc etc, but is there any way that I can be more sure of what the actual problem is or are these clues I am mentioning proof enough, is there any chance that evening the bite could fix this?.. thanks kindly, brenda