It's reasonably possible at events. Cars and Coffee works great, since everybody wants to talk about their car. I doubt it will work at the dentist, since nobody really wants to be there in the first place. Maybe if they're wearing a shirt or something you can compliment or ask about and then can use that as a springboard?
If you're the dictionary definition of an extrovert you can probably still make it work, but you'll really stand out, and you'll be rejected a lot.