Functional appliances are used to adjust the position of your teeth and jaws during orthodontic treatment. They can be used alone or before and after treatment with braces. These appliances vary in design and can have many names, but all usually have a metal bow across the top incisors that's inserted into an acrylic base. Functional appliances are removable and must be replaced after cleaning. These devices may be difficult to wear in the first few weeks, as they can cause difficulty speaking, and extra salivation for a few days. These appliances have the most benefit when worn while eating. When worn in this gradual process, the mouth can become accustomed to the device. If you have discomfort after the initial period of adjustment, the device may need to be re-fitted. Contact your orthodontist for more information on functional appliances.