Applying braces or clear aligners to move misaligned teeth is only part of an orthodontist's overall mission to eliminate poor bites (malocclusions). Sometimes a malocclusion isn't caused by the teeth at all—the size of the jaw is the problem!
One type in particular, a cross-bite, often happens because the upper jaw has developed too narrowly. As a result, many of the upper teeth fit inside the lower, the opposite of normal. But a tool called a palatal expander can alleviate the problem if it's applied at an early enough age.
The device works because the upper jawbone initially forms as two halves that fit together along a center line in the roof of the mouth (the palate) running from the back of the mouth to the front. These two bone halves remain separate during childhood to facilitate jaw growth, but eventually fuse around puberty.
Consisting of two sets of wire arms joined together by a hinge mechanism in the middle, the expander device is positioned up against the palate. The orthodontist extends each arm to press against the inside of the back teeth, then adds more outward pressure by turning the mechanism in the middle with a small key. During wear, the patient or caregiver will turn the mechanism in the same way to keep up the pressure on the two sides of the jaw.
This continual pressure keeps the two bones moving away from each other and maintaining a center gap between them. In response, more bone forms on the two halves to fill the gap. In time, the newly formed bone should widen the jaw enough to correct any developing malocclusion.
Timing is everything with a palatal expander—if not used before the jaw bones fuse, the patient will need a surgical procedure to separate the bones to pursue treatment. To catch the problem early enough, children should have an orthodontic evaluation on or before they turn six. An orthodontist may be able to identify this or other emerging bite problems and intervene before it becomes worse. Taking this approach can help save you and your child more expensive orthodontic treatment down the road.