Functional appliances are used before fixed appliances, in cases where there is an increased overjet (upper teeth are prominent relative to the lower teeth). They are removable appliances that work by posturing the lower jaw forward and in doing so reducing the gap between the top and bottom teeth. Treatment time takes about 6-9 months, depending on how well they are worn and fixed appliances are usually used after this to align the teeth. This treatment is best carried out when the patient is going through the pubertal growth spurt so that jaw growth can be stimulated to help reduce the prominence of the upper teeth.
