I HAD NOVOCAINE TWICE! I had wisdom teeth removed on those days and on the first day I later went and drank a cold soda. I couldn't feel it on the right side of my face or taste it, But my bones felt the cold!
In actuality, the only reason there's a difference at all, is because the Americans, wanting to disassociate themselves from the British, deliberately changed the spellings of some of their words in around the eighteenth, nineteenth century (they claimed it was done so to remove some of the "superfluous" and "unnecessary" traits of British spelling, but it was a pretty transparent excuse). So with that in mind, the British spelling is the proper one, if only because it was the one that came first.
Personally, I'm indifferent. It's not really so much a matter of what's PROPER, it's more of a matter of...personal taste.
I actually didn't notice you had used British spelling until you brought it up in the description, and probably wouldn't have altogether if it wasn't brought up altogether.
Hey you! We should head back to my place. My wife won't notice. I'm right here dear, and I don't appreciate you saying 'I won't notice.' You know, you remind me of my wife. All she does is whine and complain to me. You know what? Forget you, I'm just going to- *falls asleep *facehoofs.