The top teeth are meant to fit over the bottom teeth like a lid. Crossbites are when the top back teeth sit behind the bottom back teeth.
We are meant to have 32 teeth in total if you include the wisdom teeth. Occasionally, an individual is born with one or several adult teeth missing. There is often a genetic link with this trait.
This is when teeth are obstructed to erupt into the mouth due to insufficient space. This commonly occurs to the first adult molars whereby they become stuck underneath the baby molars.
This is when a tooth does not develop in the right position and becomes stuck and unable to come through into the mouth. This is sometimes seen with canine teeth.