Orthopedic orthodontics refers to the branch of orthodontics that addresses jaw imbalances in children. When the upper and/or lower jaws do not develop properly relative to each other, the teeth will not fit together or function properly. It is often possible by using orthopedic appliances in young, growing children to change the relative size and position of the jaws. This allows the teeth to fit better and quite possibly avoid more invasive treatments later such as jaw surgery. The two appliances used most commonly are headgear and protraction headgear.