Palatal expander. Animation showing a palatal expander, an orthodontic device used to widen the upper jaw, and braces. The expander fits into the roof of the mouth (palate) and is attached to the upper molars. Turning of the central screw applies a gentle force against the teeth to gradually push them apart. Once the palate has been expanded braces are often needed to realign the teeth.HD master is flattened onto a black background, as seen in this preview. The original file has a transparent alpha channel and is available as the HD master of clip K003 3757.