There are some dental terms for what you are, most likely, seeing.
The first is, crossbite.
If you look on the left hand side of this picture you will see a crossbite.
The top teeth are supposed to come out over the tops
of the bottom teeth (like the right side).
The next thing you might be seeing is an underbite.
That is where the bottom front teeth protrude further then the upper teeth.
Notice in this picture there is no crossbite. The back teeth are all in correct position.
It really depends on the age of the child as to how much you are going
to worry about either of these conditions.
If your child is over the age of about 6 and their permanent teeth are crossed or over-bit then you for sure need to see an orthodontist.
If your child is younger and still in the process of getting all of their baby teeth in then the concern may not be as pressing. In this case simply have your dentist take a look at your child's tooth positioning during their next cleaning.