Children normally begin losing their baby teeth from around 6 years old. From 6-12 years, youngsters have a mix of grown-up as well as primary teeth. By about 12 years, many children have all their adult teeth with the exception of the third molars ( knowledge teeth). There are 32 grown-up teeth. If your youngster's primary teeth came late, the grown-up teeth will probably be late also. If you're worried about kids dentist and your child's teeth growth, see your dentist.