Is there anybody out here that has gotten fitted for a top denture without getting an impression of your teeth?

done first? The reason I as is because I lost almost all of my top teeth in a head on collision with a tree, I already did not have any of my wisdom teeth, so I was wondering can a denture lab tech give me a nice natural looking top denture without knowing what my top teeth looked like. Please share your experience of wearing a top full denture with all of your real bottom teeth. I am so afraid that these dentures will make me look totally different.