It should go away on its own, but if it doesn't in a month or so, consult your dentist and perhaps they could laser it or refer you to an oral surgeon for treatment. As long as it doesn't hurt a lot, isn't hot or very red, you don't have a fever, and it doesn't seem infected you'll probably be just fine. If in question, go back to the dentist and see what they say. Healing time varies person-to-person. With that said, take vitamin C as it helps heal tissue. Good luck.
Seeing an oral surgeon is advised.