Hi, I'm A 20 Year Old Female And It's Been

Hi, I'm a 20 year old female and it's been a few years since I've been to the dentist as I have a fear of going. I've had a bit of plaque build up on the sides of my top molars, and today a bit of plaque fell off in a chunk from one of them. My tooth is still in place and I don't feel any pain at all, but I can feel a gap where it used to be with my tongue and it's just making me really scared that my teeth are going to fall out or something. I was wondering what I should do about it, and if I were to go see a dentist what they would do?