Can anyone explain a palate expander?

Appliance: Rapid palatal expanders are orthodontic appliances cemented to upper back teeth that have a screwjack. This is turned a small amount at regular intervals to separate plates of palatal bone which stimulates additional bone growth at the suture where the bony plates meet. This growth causes the palate to expand other removable appliances can accomplish the same thing.

See below: Palatal expansion is used when a young patient has a narrow or constricted palate. The goal is to widen the palate, or "roof" of the mouth which should be slightly wider than the mandible to provide optimum occlusion, which is to say, so that your teeth fit together the way god designed them to be. If the palate is narrow the upper teeth are slightly inside the lower teeth creating a cross bite.

Palatal Expansion: Palatal expander is a device to expand the width of the palate and ultimately the intermolar distance in the maxilla. It is used extensively in orthodontic treatment to correct posterior crossbite and narrow airway. Palatal expander is most effective when used with patient under 22 years old since the palatal suture usually has not completely fused and thus produce more translational movement.

Transverse : Palate expander used when upper jaw narrower than it should be in relation to width of lower jaw. It corrects skeletal relationship in the transverse (side-to-side) dimension. It also creates more room in the upper jaw for the permanent teeth that starting forming before your child was born. Ask your pediatric dental specialist or orthodontic specialist to do "show & tell". It's a good thing.