Most kids are pretty intuitive. If your "talking up" was a little too cheerful and enthusiastic, your daughter probably thought she was smelling a rat. Plus kids are quite reasonably resistant to having strangers put fingers and tools in their mouths in a strange environment.
Seems you could do two things. Prefereably, since she's so young, back off on the return appointment if she had no obvious problems, give the issue a few months to cool, and reintroduce the subject with books, videos, or whatever resources you can find. Puppets can be good, both to help her know what to expect and to let her express her feelings. Meanwhile, just keep quietly educating her about the importance of healthy teeth, and mention once in awhile that the dentist is a friend who will help her mouth stay healthy.
Alternatively, just be honest. If there's some urgent reason you can't put this off, tell her that lots of kids feel scared of the dentist, but they turn out to be okay. Tell her that she must do this, that she doesn't have to like it, that it's important and necessary, that you'll be right there with her, that it can't wait (if indeed it can't). Tell her what's going to happen in some detail, since fear of the unknown is way scarier. Be firm, gentle, patient, and extremely calm. She will still resist, but your firmness and calmness may be something of an emotional anchor during the procedure.
Afterward, thank her for her cooperation and take her for a treat. (Don't bribe her with a promise of a treat beforehand, however. Bribes backfire, if not sooner, then later.) Over the treat, talk over her experience with very calm, accurate observations. If she seemed to be in pain at any point, don't discount her pain, or she'll trust you even less the next time. Just observe that the discomfort only lasted a little while and now it's gone and her teeth are healthy.
(I wrote comments above before seeing all the recommendations for pediatric dentists. What a concept! I was born too early for that wonderful innovation, and so was my grown daughter.)