I just went to foursmile today to have my teeth straightened. How does a small camera take continuous pictures in the mouth?

Hahaha, this is called 3D oral scan. Normal correction is done by clenching your teeth. It makes a bunch of sticky stuff that you can’t bite down and it tastes disgusting. It’s easy to retching. There is no need for this, just scan it ~ indirectly reducing a lot of pain. 3D oral scanning is equivalent to taking a circle of photos for you. These photos are then stitched together to create a model of your teeth.