A dentist that fully adores kids.
You will know this the moment you call or drop by to schedule an appointment. Ask the secretary if they use simple facilities or materials to help put kids at ease before or while having their turn at the dental chair. These assistants will definitely give you an idea if they can cater to these kids or if their client specializes in just doing cosmetic or preventive dentistry
for adult clients.
A dentist has great reviews in parenting and family oriented blogs and magazines.
Yes, forum posts and articles from reputable sources count especially if fellow parents vouch for a dentist's expertise in handling young patients.
A dentist that your family and friends trust.
If you decide to go with your family and friends for advice, then take a hint when most of them refer you to the same person. This may be a giveaway on how much they like their dental help and services especially when it comes to serving younger patients like your kids.