Can you tell me is it normal that adult tooth coming in behind baby tooth?

This can happen : And I have observed this hundreds of times over the years. This may signify a crowding problem. Tends to happen in the front teeth in some children w limited space. Please make sure the child is evaluated by his/her dentist and ask about this issue. Early orthodontic consult might be indicated and maybe early interceptive treatment may be in order, depends on age and situation.

Not normal: Bring your child to a children's dentist, or an orthodontist. The new tooth should come from under the baby tooth and push it out. If it is coming from behind there is a problem.

If Lower = Yes: The lower front permanent teeth start their eruption pattern behind the baby teeth. Then they will move up and forward to replace the baby teeth.

No, but common: Ideally the permanent tooth should come up right under the baby tooth and take its place. Sometimes the permanent tooth comes up behind the baby tooth and does not push it out. We give our patients about two weeks to get the offending baby tooth out on its own. If they can not in that time period then we extract the baby tooth. They should not both be present for an extended time.

Yes and quite often: On the lower anterior (front, ) it is not uncommon at all for the permanent central and/or lateral incisors to erupt behind the baby teeth. Don't immediately have the baby teeth extracted or pull them yourself. See a dentist to get advice.

Oops: Very common but not "normal." Often indicates an arch length insufficiency (crowding) problem. If baby tooth not gone in 2 weeks important to see Dentist to have it removed. Remember, when there is one eruption anomaly there are often multiple eruption anomalies. 1st Orthodontic examination age 7, or the moment thou notice a problem. Best to have dent-facial development evaluation. See Ortho