From personal experience (well, my GF's) I know that most OBGYN's know almost nothing about vaginal pain. To the point where it almost not worth going. Seriously. You will be told "it's all in your head" or "use more lube" or "it'll go away" Still, it probably worth going, you might get lucky and find someone who actually cares and is willing to do some research.
One possible, less extreme, explanation might just be lack of use. I've had girlfriends who, after a break from sex due to distance or whatever, needed a bit of time to get used to it again. It was uncomfortable for the first couple times, then started to feel good again. So maybe a solution would be to see your dentist less frequently (or, alternatively, have more sex!)
