M.C.
Totally normal. Your mouth was in an open position for 2-1/2 hours...yep, it will be sore. My guess is the dryness caused the soreness in your throat. Dentists put all kinds of things in your mouth while they do their work. Some of the vibrations from the drill, stuff that comes out of your teeth while drilling...all can cause mouth/sore throat pain. Do you sensitive teeth? When I have fillings, root canals or crowns done, I can hurt for up to a week or more. Heck, I had a root canal done in February of 2012 on a top front tooth...it is still very sensitive.
There are a couple of products over the counter that work for great for oral pain and sensitivity. Rincinol is an oral rinse that helps soothe pain. It's great for canker sores. Orabase by Colgate is also very good for pain relief. You can also do an old-fashion water/table salt rinse for relief. I also brush my teeth with Sensodyne toothpaste--great for sensitive teeth.
I hope you feel better:)