If a child loses a permanent tooth then they will be without that tooth.
Once a child loses a permanent tooth no other tooth will grow back in it's place so the worst that would happen is the child has no tooth in that area anymore.
The child can still eat and still have the other teeth.
When a child loses the baby teeth new teeth grow in their place to replace those temporary teeth with permanent adult teeth.
But when a child loses the permanent teeth there are no other teeth that can grow in it's place.
So the child would have to have a dental implant put in or just do without the tooth.
If a child loses a tooth due to injury then they should see a dentist to make sure nothing is infected or if the permanent tooth suddenly falls out then the child may have gum disease or other tooth infection that should be looked at.