Children are a special case because they are growing. This makes them ideal subjects for orthopedic intervention. ("Ortho" means to straighten and "pedo" means child.) Because they are fairly pliable and the bone is relatively soft and always growing and changing, it is easy to guide the bone growth in children through external means.An oak tree, tied in a knot when it is a tiny sapling, will grow in a hundred years into a huge oak tree with a knot tied in its trunk. What was possible when the tree was immature becomes impossible in maturity. (There is some argument about whether the movement of children's teeth is actually faster than that of adults, but there is no argument about the ease of movement due to the growth factor.)

As every mother knows, their children grow faster at some ages than at others. Therefore, orthodontists want to time their treatments for the ages when the child is mature enough to cooperate with treatment, and also when the bone is growing most rapidly. The optimum age for beginning treatment depends upon the specific deformity that the orthodontist needs to correct, but the best age for evaluation of that specific deformity is usually age 7 because that is the age when both factors tend to coincide for the treatment of certain skeletal deformities. A major growth spurt takes place at puberty, and orthodontists like to take advantage of this as well. When deformities are assessed early and treated prior to the time that they have fully developed, we have "intercepted" the problem and this is referred to as interceptive orthodontics.