My 2 year old son's front teeth look stained for the past few months. what is causing this?

Multiple causes: Staining in the front teeth could be the result of something as simple as staining from food that has not been cleaned from the teeth after feeding, to discoloration due to decay or trauma. When in doubt it is always wise to have the child examined by a pediatric dentist or your general dentist to find out for sure what the cause is.

Many reasons: Could be what dentists call the enamel pellicle, a single layer of cells on the outside of the tooth. Could be cavity. Could be nerve of tooth died after a fall. Could be tooth just isn't clean enough. If your child has never seen a dentist you're a year overdue. Look for a pediatric dental specialist for the same reason you see a pediatrician. Go now please.