A palatal expander is an appliance that fits into the roof of your mouth (palate). It widens your palate to improve the way your upper and lower jaws and teeth fit together (your bite). You wear a palatal expander for about 6 months. During the first few weeks, you or your Orthodontist may expand the appliance.
In about a week or so, you may see spaces between your teeth. That's a sign the expander is working. Your teeth will shift after the expansion to fill in the gaps.