Pediatric Dentists specialize in pedodontics. In other words these are kids dentists who typically deal with treating the teeth of children up through adolescents. This speciality is recognized by the American Dental Association and requires years of extra training after dental school.
These kids dentists will often deal exclusively with children and are highly skilled in making childen comfortable and performing cleaning check ups and proceedures with as little pain as possible. They also are very knowledgeable in preventing tooth decay and teaching young children good oral hygiene.
If you have a young son or daughter, I recommend finding a good local doctor who specializes in treating kid's teeth.