UNDERBITE The lower teeth protrude past the front teeth. An underbite is usually caused by undergrowth of the upper jaw, overgrowth of the lower jaw, or a combination of the two (Class III Relationship). Underbite can also be caused by flared upper incisors, missing lower teeth or a combination of all the above. Early correction of underbite is recommended. Underbite should be corrected because it can: prevent proper functioning of the front teeth or molars which can lead to premature wear of the teeth cause chewing or eating problems cause jaw or joint problems make your smile less attractive

This is what underbite looks like:

Underbite

How can an underbite be orthodontically corrected?

Underbite can be corrected through growth modification of the jaws; extraction of teeth; and in some cases surgical correction of the jaws.