B.C.
When a baby tooth grows, it has roots just like any other tooth.
An adult tooth develops beneath it and as the adult tooth grows, it dissolves the roots of the baby tooth. As the root dissolves, the baby tooth becomes more and more wiggly and eventually it falls out. It's usually a painless process and very little blood is involved. And within several weeks you'll see the adult tooth emerging from where the baby tooth used to be.
Most of the time this all happens flawlessly, but occasionally it does not go smoothly. In the case where an adult tooth does not come in directly below the baby tooth, sometimes the roots of the baby tooth are not dissolved or not dissolved completely. In that case you need to see a dentist about having that baby tooth pulled so it does not throw off the alignment of the adult teeth.
I've always had a good family dentist who treats all of us.
I never worried about finding a pediatric dentist, but I guess it depends upon finding someone who you are happy with.