Well you still have plenty of obstacles (or events?) in your way prior to becoming a pediatric dentist, so it's best to take care of those short-term goals first, and then move on, but I think it's great that you have some idea of what you'd like to do in the long term.
Peds residencies are getting more and more competitive. We've got a couple guests who have far better information than I do, and I suspect they'll post some of the application specifics.
Your first priority is to get into dental school, and then maintain good grades and class standing, as well as doing well on the NBDE. That really is *the* only path, and there isn't much deviation from it.
Also, keep your mind open when you enter dental school. Don't limit yourself or shut out anything that doesn't fall in line with your goal of becoming a pediatric dentist. It could be that peds is what lured you into dentistry, but you may find out that your talents and abilities are actually better suited for another area of the profession. There isn't anything wrong with that process, and it's one that most of us will go through.
Good luck.