Why do children need to have dental x-rays taken every six months?

Children's teeth are constantly changing underneath the gum line. If they have erupting teeth, baby teeth that are still coming out, x-rays help in assessing the position and intercepting areas that can affect adult teeth. An example of this is canine impaction where the canine or the Dracula tooth dives into the lateral front tooth. If not caught on time, it can destroy the root and cause the child to lose a front tooth.

If the child is in orthodontics or having braces, dental x-rays help to monitor roots that may be shortening or receding. This can also happen in adults. If the roots are seen to be shortening, the orthodontist is alerted to act accordingly to stop that and prevent it from progressing further. If the root length shortens, the chances of losing teeth is a lot greater because there's no root length to protect the tooth and allow it to stay more embedded in the bald socket.

The enamel or the shiny layer on the surface of baby teeth is a lot thinner than it is for adults. So a child that gets a cavity starts at the shiny part, if not caught early or closely monitored, it can easily grow deeply into the nerve and necessitate further dental treatment like a baby root canal on a crown. Whereas in adults, it'll progress much slower.

The three reasons are: to track the position of the teeth to ensure they're aligning properly and no other tooth is at risk of being lost; to monitor for possible root length shortening if the child is in braces; and to monitor the growth of cavities over time and act if the cavities are growing really fast.