Kids usually begin losing their primary teeth from around 6 years old. From 6-12 years, children have a mixture of grown-up and baby teeth. By about 12 years, many kids have all their adult teeth with the exception of the 3rd molars (wisdom teeth). There are 32 adult teeth. If your youngster's baby teeth came late, the adult teeth will probably be late too. If you're worried about kids dentist and your kid's teeth advancement, see your dental professional.