I Have A Lump On My Gum Line It Doesn't

I have a lump on my gum line it doesn't hurt though I went to the doctor and they said X-rays didn't show anything so they told me to go to the denist, now I went to a denist and she said if it gets bigger to come back.. I want it gone I've had it for along time now. And you help me and figure out who I should go see