I have heard of expansion; what is expansion?
Often there is a disparity in the widths of the upper and lower jaw, the most common being where the upper jaw is narrow compared to the lower. When this happens, the upper teeth generally will not fit well with the lowers. The overt condition is known as “crossbite.” Because this is a problem of the jaws, the muscles that attach between the upper and lower jaws are out of harmony as well; and, in fact, are a large part of the reason that the teeth do not fit well. Simply tipping the upper teeth out will predictably result in a relapse to or toward the original condition. Other side-effects of a constricted upper jaw (maxilla) can be inadequate space for all of the upper teeth – remember from geometry that the circumference is a function of the width. Many of the patients who have a constricted maxilla also have difficulty breathing well through their nose. When done effectively, widening their maxilla will often improve their ability to breathe through their nose. This is usually the
