It is not a good idea to heat teflon to high temperatures

You should never heat up an empty teflon-coated frying pan or pot, no matter what the chefs tell you.

The teflon can release a gas that will cause birds to drop over dead, a la canary in a coal mine.

http://www.time.com/time/magazine/article/0,9171,1200779,00.html

Actually, if possible, you should not raise the temperature of food above the boiling point of water... but that is another story.