those are good links Yuletide...sorry to hear about your day so far naughtymummy!
I think the key here is to take the pressure of yourself. You say he's still refusing to brush his teeth; then forget it. Don't press the issue any more about the teeth and going out, he's beside himself and it's pointless.
Don't worry about him having 'won'; in fact it's only him who has lost out, he's lost out on a nice playtime with you and on his one to one time with you. Just be sympathetic if you can; he's lost out on that and he's just not able to control these feelings right now.
I think the best thing on that link was the bit where it says "you are not responsible for causing, or stopping, his tantrums".
That's SOOOOO true. He just has feelings he can't control, that's part of being 2. Your only responsiblity is to be there as a reassuring presence, to let him know that when he's feeling able to, you are ready to talk/hug/play, whatever he needs.
I found with my ds that we needed to be separated completely during a real tantrum, as even if in the same room but ignoring him, I became the focus of his anger. If he was on his own in his room, he calmed quicker.
I'm hesitant to ask because I know ALL kids have tantrums and it's probably nothing to do with your approach at all, but were you a bit straight down the line with the tooth brushing and going to the loo thing possibly? My ds was immediately ready with 'No!' if I told him to do something and it was at this age that he responded brilliantly to games/challenges; eg oh no, you can't clean your teeth with this, it's mud! oh my goodness it's making your teeth go brown, eeuuuuurgh! He thought this sort of thing was hilarious and used to get dressed/brushed without noticing!
hth.