Class 1

In this case the teeth meet in good positions and the overbite and overjet are correct, but the teeth are crowded. Space may be gained by removing some of the teeth, depending on the degree of overcrowding.

Class 2, division 1

The upper teeth are projecting forwards off the lower teeth, and the upper incisors are proclined. Additionally, there may be crowding. Depending on the degree of discrepancy headgear, extractions or surgery may be needed to achieve correction.

Class 2, division 2

The upper teeth are again protrusive, the upper incisors are retroclined. The overjet may not be greatly changed but the overbite is often greatly increased, giving a deep bite.

Class 3

In this case the lower teeth are positioned ahead of the uppers (a reverse overjet). There is often an associated jaw malalignment, either upper or lower. These patients often need a combination of braces and a jaw operation to treat well. As the lower jaw is one of the last bones to stop growing, this treatment is delayed until the patient is adult.