I noticed my 2yo dd's top molar looked like that too and thought it strange, but the dentist didn't say anything a few weeks ago and I forgot to ask.
One thing I notice lately is that she is always putting her fingers in her mouth and chewing on them. When I took her to the dentist for the first time it was because she said it hurt her teeth to nurse and she was chewing on her fingers a lot. The dentist said that all 4 molars were basically in and that there might just be a little inflammation left on one of them...but that was almost 4 weeks ago. I can't think that is still inflamed.
She doesn't say her teeth hurt anymore, but she still chews on her fingers a lot. It's not a sucking fixation. She's basically sticking fingers in her mouth and chewing on them. Any ideas why she would be doing that and how to get it to stop? I always redirect her to take her fingers out and she will, but then they go back in shortly afterward.
Since we were on the discussion on back teeth, I thought this might fit in here. Sorry to hijack.