I think someone posted something similar recently but just was wondering if anyone got any answers:

I had tooth #26 (lower toward front) extracted after infection (I had a root canal on the tooth for over 20 years, bit something hard and must have caused a chain reaction). The site was bone grafted and after 4 months I tried getting an implant which failed after 10 days, the oral surgeon did not understand why and so no signs of infection. I tried inserting the implant again and so far I am along 2 weeks along and everything seems OK so far (I am thinking the flipper I wore on the site caused undue pressure before). However there is a hard bump in the gum, below where the tooth was. I asked both my oral surgeon and dentist about this and they said it wasn't anything to worry about, that nothing was showing up in the X-ray. The oral surgeon said that it was part of my chin bone (sure doesn't feel like it because it's not that way on the other side of the mouth).

I am wondering if there was a cyst there, or infection, would it be possible that it would only show up in a more advanced scan? My oral surgeon is not equipped with anything besides a panoramic x ray machine.