What appliance is my dentist installing?

Today my dentist numbed me up and started drilling into the bone of the roof of my mouth. They screwed in a screw thing. This will be the anchor for my new appliance (woo-hoo). What is this appliance called and what will it be like.|||This may be something called a palatal expander. If your teeth are not in ideal occlusion, this is used to widen the roof of your mouth. If you'd like to compare pictures of your teeth with what I'm talking about, try to google "palatal expander" or "crossbite" and see if that resembles what you have in your mouth.|||The only thing I can think of, is that he installed a mini implant on the roof of your mouth. This will help aid braces in moving your teeth. Now if you don't have braces, I can't think of what appliance that is you're talking about.. sorry.