Class II problems represent abnormal bite relationshipts in which the upper jaw and teeth project ahead of the lower jaw. This is called 'overjet'. Class II patients usually exhibit a convex facial profile with a deficient chin prominence. Typically, a Class II problem is inherited and results in a shorter than normal lower jaw. Other factors such as persistent thumb sucking can aggravate these problems. Correction of this disorder generally requires influencing facial growth to bring the upper and lower jaws and teeth into their proper position.