TOOTH OVERBITE:
The ideal bite/occlusion is when the upper teeth are overbiting the lower teeth in the front, and all around to the back. If the lower teeth are outside the upper teeth, this is referred to as a crossbite.
However, too much overbite is also not a good thing. How much is too much needs to be evaluated by your dentist. Below are the different types of occlusion.
Malocclusion is the term used when the occlusion, or bite, is not ideal. This can refer to the aforementioned crossbite, too much of an over/under bite as pictured below, or other other discrepancies.
Malocclusion Diagram:
