1. “Expanders make your face wider.” The main job of a palatal expander is to fix a narrow upper jaw, when the top teeth bite inside the bottom teeth. The goal is to help the top and bottom jaws fit together better. Most of the change happens inside the mouth, so people usually don’t suddenly look wider in the face. 2. “Palatal expansion fixes breathing or sleep problems.” Sometimes expansion can help create more space in the nasal area, and that may improve breathing for some people who have a diagnosis of obstructive sleep apnoea. But breathing and sleep problems can have many different causes, like the nose, tonsils, allergies, or airway anatomy. So expansion isn’t a guaranteed fix for everyone. 3. “If teeth are crowded, you should expand the jaw.” Crowding and a narrow jaw are two different problems. Expanders are used when the upper jaw is too narrow compared to the lower jaw. Crowding usually happens when there isn’t enough room for the teeth themselves, which is treated by di...