Smiling at a dog is actually a very aggressive thing to do. Showing the teeth to almost any animal is aggressive. You probably just cowed it with that move. Odd, though that is all it took.
As a student of anthropology, some of the school work had to do with behavioral studies of primates - monkeys and apes in particular. Based on what I had learned, I went to the Lincoln Park Zoo in Chicago, and went to the ape house. In one cage of baboons, I looked down, glanced at the apes out of the corner of my eye, and in general acted submissive. No reaction.
Another cage of baboons who were just calmly sitting there, I stared at one male, very obviously, and within a few seconds he went through all of the textbook stages - started pacing, then started eyelid flipping. started grimacing and showing his teeth, finally got so worked up he started hooting which set the others off. Kinda cool to do that.