Thanks for all your replies.
QUOTE(TSax @ Feb 7 2010, 07:51 PM)

It depends on the type of pad. The thicker ones that are rubbery last me no time at all before I start biting them and having to spit out chunks of rubber. I find the thin ones much better. I do get toothmarks and an air bubble fairly quickly, but that doesn't seem to impact their effectiveness. It would hamper me if I wanted to adjust the position of my top teeth on the mouthpiece - I'de probably need to put a new one on. I too have slightly wonky top teeth.
That sounds like me. I hate the rubber ones because I find chunks of it in my mouth for days after playing!
The pads wearing down doesn't actually affect my playing, but the dentist is trying to work out if playing the clarinet/sax is making my teeth more wonky, as so asked me to change the pads as soon as they started showing signs of wear, however, they were wearing so quickly that I'd get through a few each week!