If your jaws don’t line up, your teeth don’t meet. The same is true if your teeth are turned, crowded, or missing. Bite problems fall into three main classes. You may have one or more of these common bite problems.
Jaws line up – Normal bite with crooked teeth (Class I): Jaws line up, but teeth may be crowded, turned, or spaced apart, some may be trapped in the bone under the gum surface (impacted).
Jaws don’t line up – Overbite (Class II): Upper jaw is too large and sticks out (protrudes) over the lower jaw. Or the lower jaw is too small and too far back. Upper teeth protrude, often called “buckteeth.”
Jaws don’t line up – Underbite (Class III): Lower jaw is too large or too far forward. Or the upper jaw is too small. Lower teeth close in front of upper teeth.
Get more detailed information about common bite problems here.