To be honest it takes a lot of shots to get one to focus. I wish I had a camera with a manual focus. Anyways, the flash is bright enough to go through the cheeks and light up the mouth, you can also open up wider and let some of the flash into your mouth. There's a setting on my camera that, when done right, shows details up close. Looks like a flower on the button if you have it. Just be sure to close your eyes or you will blind yourself for a bit
Yeah I have that setting, My camera's just not working too well... though it was a cheap coolpix. I guess I shouldn't expect quality for a hundred bucks. Makes me feel better to know that you had to take the picture multiple times though.