Overjet is measure of the horizontal relationship of the upper and lower front teeth. It is often called "buck teeth", and is commonly confused with overbite. Excessive overjet may be caused by improper alignment of the molars (Class II relationship); a skeletal imbalance of the upper and lower jaw(s); flared upper incisors; missing lower teeth; crowded or tipped back lower teeth, or a combination of all the above. In addition, oral habits such as thumb or finger sucking or tongue thrusting can exacerbate the condition.
Overjet should be corrected because it can:
Prevent proper functioning of the front teeth
Lead to premature wear
Make your smile less attractive