Difficult to predict the magnitude and direction of future facial growth because of tremendous individual variation Chronological age cannot be used to predict the onset of the adolescent growth spurt. Some cephalometric features can help in predicting the likely directionof future mandibular growth rotations (not entirely reliable).
Concerning timing, mandibular growth follows the general body pattern of skeletal growth which accelerates at puberty Hence, serial statural height measurements and the presence of secondary sexual characteristics can help determine the onset and stage of the pubertal growth spurt and associated acceleration in mandibular growth.
Thus it is useful in determine the timing to start of functional appliance treatment. The growth spurt (variable, both within and between populations) Boys: 14 ± 2 years Girls: 12 ± 2 years
Timing of Tx Effective during active growth The faster the growth, the faster the response, the shorter the tx time (theoretically) Most common time for tx - pubertal growth spurt (difficult to predict accurately) Early tx: 9-10 yrs Definitive tx: 12-13yrs (late mixed) Key factor : pt is actively growing
Early tx Ideal tx time – when 4 upper incisors have erupted Most common - correction of large OJ caused by retrognathic mandible Tx - Reposition mandible forward Tx discontinued once correction achieved Some relapse will occur
Early tx To intercept a developing problem Improve aesthetics (improve self-esteem) Decreased trauma risk to anterior teeth Early correction of deleterious habit Early tx might produces larger skeletal effects, but not supported by studies. In fact, more prolonged total tx time is reported.
Definitive tx During pubertal growth spurt Usually all permanent teeth have erupted Correction of max-mand discrepancy usually followed by fixed appliance tx Functional appliance may also be used during fixed appliance tx
Tx Protocol FullFull-time wear for first 6 months Worn at all times including eating and sleeping Removed only for brushing of teeth Not to be worn during sporting activities NightNight-time wear for next 6 6-9 months Finishing may be undertaken with fixed appliances fixed appliances