Headgear creates forces that guide the growth of the face and jaw. It also prevents teeth from moving in an undesired direction.
It places pressure against the upper teeth and jaw to hold the teeth in position or help move them back into better positions. It can also be used as an "orthopedic" appliance, helping control the jaw growth by holding the upper jaw and allowing the lower jaw to grow forward.
Alternately it may act as an anchor for the molars in cases where an extraction of premolar teeth has occurred.
Headgear is used to assist in closing spaces and reduce front tooth protrusion in some cases. Changes to the jaw take place over an extended time period, while the patient is growing.
To produce a successful treatment result, the headgear must be worn specifically as instructed by the orthodontist (most cases require 12hrs/day). Therefore, compliance is essential.