Most pediatric dentists these days are "in network" with one or more dental insurance companies. Because the majority of families have some sort of coverage, it only makes sense that a practice would accept the major carriers. Why, because many families with several children would find it difficult, if not impossible, to pay out of pocket for dental care, especially extensive restorative treatment.
So, when your employer has a sign-up for dental insurance here's what I suggest. Do a little homework and choose a plan that many dentists are a part of. I have seen people accept from their employer (or buy for themselves) an inexpensive insurance pan, but then can't find any dentists who will take it.
Here are some of the main dental insurance companies that I would recommend you look at before purchasing one: Aetna, Anthem, Assurant, Cigna, Delta, Guardian, MetLife, Principal. These are the most common ones that most pediatric dentists would work with. Keep in mind there can be different "plans" withing each company's coverage. For instance, you will find more dentists accepting a PPO than a DMO. Before you chose one, I would call several offices and see which ones they participate with.
Dental insurance can certainly be frustrating at times, but it can save you a lot of money if you have several children or if one them needs extensive treatment.