Children usually start losing their baby teeth from around 6 years old. From 6-12 years, youngsters have a combination of adult and baby teeth. By about 12 years, a lot of kids have all their grown-up teeth with the exception of the 3rd molars ( knowledge teeth). There are 32 grown-up teeth. If your child's primary teeth came late, the grown-up teeth will possibly be late also. If you're worried regarding kids dentist and your child's teeth development, see your dental practitioner.