pimple on my upper gum

Roughly a year ago I had a root canal on my front tooth (#5 I think?) there was a post and core placed after the RCT and the tooth was filled until a crown is put on.  In the week following the treatment my tooth was loose and somewhat painful, I sw my dentist about this, and I had an infection.  I was put on some powerful meds and 2 weeks later my tooth had solidified and I saw my dentist once again, at which time he took xray and said everything look great.  A while (i don't remember how long) after that I had a pimple form on the gum above that tooth.  If i squeeze it puss will come out now and then (no odor or taste to the puss) other times it is just a hard little bump.  What the heck is this?  I have read about the infection working its way out stuff etc.but my RCT was over a year ago, and my dentist took xrays??  Anybody familiar with this??

[aliceanya]

I had the same done. I lived with the pimple for 1 year. The dentist did not realise that I had multiple roots, more than usual. he had filled one root but not another lying directly behind. he just said that it was a gum infection so I popped it and used hydrogen peroxide wash. Evnetually I went for a second opinion and had to have the tooth extracted.  The dentist picked it up on the XRay but said it was too late to save the tooth. He showed me the tooth and the problem.The abcess (abscess) had decayed part of my jaw bone, which had to be rebuilt before an implant could be inserted. So I would get a second opinion. My present dentist knows about my multiple root canals and always Xrays from lots of angles.

[scottma]

Endodontic retreatment or periapical surgery with retrograde filling can rescue your tooth.