For the moment, I would suggest this:
Tell him that you understand that he deserves to have a fun day with friends, as every person/parent does. But that your daughter's tooth is injured and that it needs to be sooner rather than later (after the tooth dies and she's in pain all the time, for example!) and that you cannot take the time off work, so it's up to him to take her. Tell him you understand that it's a raw deal for him, but this time it's his turn to step up because you can't.
Then, immediately after the appointment, thank him genuinely for doing it (even if he was a grump and a butt about it--don't mention that part). Tell him you appreciate him being a good parent and father even when its not fun.
A couple days after that, after you've cooled off and can talk to him without going off and/or being super emotional (I say this bec. in my experience, guys hate it when we women are "emotional"), tell him that you want to talk to him about scheduling time for you do something fun for YOU. That you realized one reason you got so upset about the golfing/dentist thing was because you feel like you often have to give up your time and change your schedule at the last minute to accomodate the family, but you often feel like your family, and your husband, don't appreciate your Herculean efforts to make it all work. But that it's not their fault necessarily---that you've decided (and say this with a smile! :) is that instead of getting mad about and expecting them to think of you, you are going to tell them, including DH, what you need and make time to do fun stuff and destress.
Unfortunately, men so often don't think about it. They just don't. I think they are just not wired the same way. I've gotten into this angry/resentful cycle, a lot of times because instead of saying/telling/asking for what I need, I expect my DH to somehow psychically know, without me telling him. But this is not how he works--he can be oblivious (in a harmless, but occasionally infuriating way), and I need to point blank tell him what I need/want from him or for myself. For me, the key is to the telling/asking without being combative or sarcastic or angry, and remembering that I love him and he loves me.